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Benzie IFF, Wachtel-Galor S, editors. Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2011.

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Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition.

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Chapter 18Herbal Treatment for Dermatologic Disorders

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18.1. INTRODUCTION

Herbal therapy for skin disorders has been used for thousands of years. Even our biologically close relatives, the great apes, use herbal self-medication (Huffman 2001). Specific herbs and their uses developed regionally, based on locally available plants and through trade in ethnobotanical remedies. Systems of herbal use developed regionally in Europe, the Middle East (Ghazanfar 1994), Africa, India (Behl and Srivastava 2002), China, Japan, Australia, and the Americas. Two well-known systems still in use are the Ayurvedic herbs in India (Kapoor 1990) and herb combinations developed as part of traditional Chinese medicine (TCM) in China (Xu 2004). In Europe and the United States, use of herbs declined as purified extracts and synthetic chemical drugs became available. In recent years, there has been a resurgence of the use of herbs due to the following reasons: the side effects of chemical drugs became apparent, there was a call to return to nature, natural remedies became a part of the green revolution, and there was a return to organic produce. Herbal remedies, including those for skin disorders, are currently gaining popularity among patients and to a lesser degree among physicians. In Asia, especially in China and India, herbal treatments that have been used for centuries are now being studied scientifically. In Germany, the regulatory authority Commission E oversees herbal preparations and their recommended uses (Blumenthal et al. 1998). Currently, the United States does not regulate herbal products except as dietary supplements. There is no standardization of active ingredients, purity, or concentration. There are also no regulations governing which herbs can be marketed for specific indications.

Included in this review of herbal medications are those medications that show scientific evidence for clinical efficacy, as well as the more common herbs found to be useful in the treatment of dermatologic disorders. Information regarding the safety of each herb is also included in this chapter to better enable physicians to decide which herbal therapies they may want to use in practice. Common drug interactions and the side effects of herbal medicines that may be seen in the dermatologic setting are also included in this discussion.

18.2. BACKGROUND AND CONTEXT

In India, records of Ayurvedic medicine date back to about 3000 BC. The system of Ayurvedic medicine combines physiological and holistic principles. It is based on the concept that the human body consists of five energy elements that also make up the universe: (1) earth, (2) water, (3) fire, (4) air, and (5) space. The interactions of these five elements give rise to the three doshas (forces), seven dhatus (tissues), and three malas (waste products). All diseases are attributed to an imbalance among the three doshas (Bedi and Shenefelt 2002). Diagnosis is made by an elaborate system of examining the physical findings, pulse, and urine, as well as by an eightfold detailed examination to evaluate both the physical and mental aspects of the condition. The treatment is then tailored to suit an individual based on the findings (Routh and Bhowmik 1999).

Records of TCM date back to about 4000 years. Similar to Ayurvedic medicine, TCM also is aimed at treating the whole person. It is based on the complementary forces yin and yang. In healthy individuals, yin and yang are in balance, and illness occurs when there is inequality between the forces. The Chinese also recognize five elements: (1) earth, (2) water, (3) fire, (4) air, and (5) metal, each related to specific organs. In addition, they recognize a flow of energy, called chi or qi, through the body in 14 major meridians. The Chinese evaluate the exchange between the environment and the body, such as food, drink, and air into the body and waste leaving the body. Special attention is given to the physical examination of the tongue, iris, and pulses of the individual to determine the cause of the imbalance and then to determine the appropriate individual treatment. Treatment is usually a mixture of herbs, massage, and acupuncture (Latchman et al. 1994). An entire textbook on dermatology in TCM is available (Xu 2004).

In Western medicine, herbal therapy began as folk medicine. In the United States, it began in the colonial days, when homemade botanicals were used by women at home (Winslow and Kroll 1998). Native American use of botanical treatments also greatly influenced the use of herbal therapy in the United States. Iroquois medical botanicals in the northeastern United States became well known to the colonists (Herrick 1995). In the nineteenth century, these Old World European and Native American traditions were expanded and used by a group of physicians known as the “eclectics.” As herbal medicine continued to develop in the United States, it was further influenced by European and Chinese practices (Winston and Dattner 1999).

Herbal therapy has increased in popularity in the past two decades among patients seeking alternative treatments to conventional Western allopathic medicine. The number of visits to alternative medicine practitioners in the United States has grown rapidly and in 1997 it was estimated to be 629 million, surpassing the number of visits to all primary care physicians (Neldner 2000). Approximately US$27 billion was spent on these alternative therapies in 1997, of which US$3.24 billion was spent on herbal therapy (Klepser and Klepser 1999). It has been estimated that about 50% of the population uses some form of alternative medicine. Many patients choose not to tell this information to their physicians. The group most likely to use unconventional treatment modalities according to a previous survey consisted of nonblack, college-educated individuals between the ages of 25 and 49 years, having an annual income greater than US$35,000 (Eisenburg et al. 1993). Most patients seek alternatives because conventional therapy has failed to help them sufficiently or because they feel there are fewer side effects with the natural products. The recent increase in the use of alternative medicine has led to more research regarding alternatives and requires education of physicians on the subject to enable them to better inform and care for their patients. In the United States, herbal remedies continue to be sold as dietary supplements, with no standards of potency and efficacy required currently. The Dietary Supplement Health and Education Act of 1994 did set purity standards for some commonly used herbs. In Germany, a regulatory authority known as Commission E extensively reviewed common European botanicals. In all, Commission E evaluated the quality of evidence for the clinical efficacy, safety, and uses of 300 herbal preparations (Blumenthal et al. 1998; Bisset and Wichtl 2001). In Germany, this information has led to standardization of herbal treatments. A number of herbal therapies have stood the test of time for their efficacy in treating dermatologic conditions, with a few having significant scientific evidence of usefulness.

With alternative herbal therapies, an individual patient often treats himself or herself, many times without high-quality professional advice. Patients are advised to ensure the safe use of herbal therapies by deciding on health goals; informing themselves on efficacy, safety, interactions, and usage of the medicine; selecting therapies that are likely to achieve their goals; having a correct diagnosis before using the therapy; consulting reputable practitioners; informing the practitioners about all the remedies they are using; monitoring the effects of the remedies, both positive and negative; waiting patiently for effects to become noticeable; and adjusting doses as needed to accommodate surgery, illness, or changes in conventional therapy (Dunning 2003). Product-labeling information that the patient should look for includes the name and composition of the product, including the parts of the plant and quantity of raw material used, daily dosage and timing of dosages, allergy and other warning statements, quality and safety testing, expiration date, manufacturer, country of manufacture, claims and indications for use, and details on how to store the product (Kron 2002). The Botanical Safety Handbook (McGuffin et al. 1997) places herbs in different classes of safety, with Class 1 herbs being safe to consume appropriately, Class 2 safe to consume with restrictions (2a for external use only, 2b not for use in pregnancy, 2c not for use while nursing, and 2d indicating other specific restrictions), Class 3 herbs restricted to use only when supervised by an expert, and Class 4 herbs have insufficient data for classification of safety.

18.3. HERBAL TREATMENTS FOR DERMATOLOGIC DISORDERS

Most common dermatologic disorders have beneficial herbal treatments available. The disorders are listed in alphabetical order below.

18.3.1. Acne

Fruit acids, such as citric, gluconic, gluconolactone, glycolic, malic, and tartaric acids, used topically have demonstrated some effectiveness in treating acne because of their exfoliative properties. In one study, gluconolactone was found to be as effective in clearing inflamed and noninflamed acne lesions as 5% benzoyl peroxide and more effective than placebo (Hunt et al. 1992). Irritation is the main adverse effect of fruit acids, especially in higher concentrations. When contained in the fruit, they are Class 1.

Tannins have natural astringent properties and are used topically to treat acne. Witch hazel (Hamamelis virginiana) bark extract is commonly used as a household remedy by making a decoction from 5 to 10 g of herb in 1 cup (0.24 L) of water. Witch hazel is considered very safe to use topically and is Class 1 (McGuffin et al. 1997; Peirce, Fargis, and Scordato 1999). Similar astringents can be made from white oak tree bark or the English walnut tree bark. These preparations should be strained before use and can be used two or three times a day. Commercially available preparations are not astringent, as the tannins are lost in the distillation process (Buchness 1998).

Tea tree oil is an essential oil extracted from the leaves of Melaleuca alternifolia, a small tree indigenous to Australia. It contains approximately 100 compounds, mainly plant terpenes and their corresponding alcohols (Swords and Hunter 1978). A study of 124 patients compared 5% tea tree oil in a water-based gel with 5% benzoyl peroxide. Although the tea tree oil did not act as rapidly as benzoyl peroxide, it did show statistical improvement in the number of acne lesions at the end of 3 months, and there was a significantly lower incidence of adverse effects such as dryness, irritation, itching, and burning with tea tree oil (44%) than with benzoyl peroxide (79%; Peirce, Fargis, and Scordato 1999). There have been occasional reports of allergic contact dermatitis (de Groot and Weyland 1993; Knight and Hansen 1994; Selvaag, Eriksen, and Thure 1994) and of poisoning if taken internally (Elliot 1993; Moss 1994). However, it is the degradation products of monoterpenes in the tea tree oil that actually appear to be the sensitizing agents (Hausen, Reichling, and Harkenthal 1999). Hence, topical treatment is considered very safe.

Oral administration of vitex (Vitex agnus-castus) is effective in treating premenstrual acne. The whole-fruit extract has an amphoteric hormone-regulating effect that is thought to act on follicle-stimulating hormone and luteinizing hormone levels in the pituitary to increase progesterone levels and reduce estrogen levels. It is included in Classes 2b, 2c, and 2d, and may counteract the effectiveness of oral contraceptives. The German Commission E monographs recommend a dose of 40 mg/day. The main adverse effects reported are gastrointestinal tract distress and occurrence of rashes. It should not be taken by pregnant or nursing women (Fleming 2000).

Bitter herbs that stimulate digestive function, including acid secretion, may improve acne (Yarnell and Abascal 2006). Commission E also approved topical bittersweet nightshade (Solanum dulcamara; Fleming 2000) and orally administered brewer’s yeast (Saccharomyces cerevisiae; Fleming 2000, 118) for the treatment of acne because of their antimicrobial effects. Topical duckweed (Lemna minor) is used in China to treat acne (Fleming 2000). Herbal mixtures are also used in China both internally and externally to treat acne (Xu 2004).

18.3.2. Alopecia

Essential oils have been studied in a randomized, controlled, double-blind study of 86 patients with alopecia areata (Hey, Jamieson, and Ormerod 1998). A mixture of essential oils including thyme, rosemary, lavender, and cedarwood in carrier oils with grape seed and jojoba (a liquid wax) was massaged into the scalp daily. The control group massaged only the carrier oils into the scalp. Success was evaluated on the basis of sequential photographs, by both a six-point scale and a computerized analysis of areas of alopecia. The treatment group had a statistically significant improvement over the control group (44% vs. 15%). There were no reported adverse effects.

A double-blind study that lasted 6 months and in which 396 patients participated evaluated the topical use of a Chinese herbal formula, Dabao (manufactured by Engelbert & Vialle, Venlo, Netherlands), for the treatment of androgenic alopecia (Kessels et al. 1991). The ingredients of Dabao include 50% ethanol, 42% water, and 8% Chinese herbal extracts, including saffron flowers, mulberry leaves, stemona root, fruits of the pepper plant, sesame leaves, skin of the Szechuan pepper fruit, ginger root, Chinese angelica root, bark of the pseudolarix, and fruit of the hawthorn plant. The ingredients of the placebo included 50% ethanol, 48% water, and 2% odorizing and coloring agents consisting of cherry laurel water, cinnamon water, licorice syrup, sugar syrup, and a solution of burned sugar. In both groups, there was an increase in nonvellus hairs. Although the Dabao group was statistically superior to the placebo group in number of nonvellus hairs, the cosmetic improvement in both groups was minimal. There were no reported adverse effects. Other TCM herbal mixtures have also been used for alopecia areata (Xu 2004).

18.3.3. Bacterial And Fungal Infections Of Skin

Garlic (Allium sativum) contains ajoene, which has been demonstrated to exhibit antifungal activity. In a study of 34 patients treated topically with 0.4% ajoene cream once a day for tinea pedis, 79% noted clearing within 7 days and the remainder reported clearing within 14 days. In a 3-month follow-up, all participants remained free of fungus (Ledezma, De Sousa, and Jorquera 1996). Contact dermatitis has occasionally been reported with frequent topical exposure (Fleming 2000). Oral administration should be avoided while breast-feeding as this is regarded as a Class 2c herb (McGuffin et al. 1997). Prolonged bleeding may occur when garlic is taken orally (Fleming 2000).

Tea tree oil (see Section 18.3.1 for a description of tea tree oil) is applied topically for treatment of bacterial and fungal infections. Tea tree oil has shown in vitro activity against a wide variety of microorganisms, including Propionibacterium acnes, Staphylococcus aureus, Escherichia coli, Candida albicans, Trichophyton mentagrophytes, and Trichophyton rubrum (Beylier 1979; Williams, Home, and Zang 1988). Tea tree oil 10% cream was compared in a randomized, double-blind trial of 104 patients with 1% tolnaftate cream and placebo cream. Although symptomatic relief was comparable in tea tree oil and tolnaftate groups, there was significantly greater mycologic cure in the tolnaftate group (85%) than the tea tree oil group (30%). Cure rates between the tea tree oil and placebo groups were not statistically different (Tong, Altman, and Barnetson 1992). Another randomized, double-blind study of 117 patients compared a solution of 100% tea tree oil with 1% clotrimazole solution in the treatment of onychomycosis. The two groups showed comparable results after 6 months of treatment in terms of mycologic cure (11% for clotrimazole and 18% for tea tree oil), clinical assessment, and subjective rating of appearance and symptoms (61% for clotrimazole and 60% for tea tree oil; Buck, Nidorf, and Addini 1994). Tea tree oil may thus have a role in at least the symptomatic treatment of tinea pedis, onychomycosis, and other superficial wounds. However, it should not be used on burns because of its cytolytic effect on epithelial cells and fibroblasts (Faoagali, George, and Leditschke 1997).

Thyme oil from thyme (Thymus vulgaris) has been used topically as an antibacterial and an anticandidal agent (van Wyk et al. 2004), and is Class 1 (McGuffin et al. 1997). The traditional Korean antifungal herb Galla rhois was found to have a methanol extract active against Candida albicans (Seong 2007). The TCM herbal mixtures for treating bacterial and fungal infections of the skin are extensively discussed by Xu (2004).

18.3.4. Chronic Venous Insufficiency

Chronic venous insufficiency (CVI) and varicosities occur in at least 10–15% of men and 20–25% of women (Callam 1994) and results in and morbidity. Compliance with current treatments such as compression stockings is poor, leading to the search for alternative therapies (Abascal and Yarnell 2007).

The German Commission E approves the oral administration of butcher’s broom (Ruscus acuteatus) and sweet clover (Melilotus officinalis) for relief from symptoms such as pain, heaviness, pruritus, and swelling associated with venous insufficiency. In animal studies, butcher’s broom was demonstrated to increase venous tone and to also exhibit diuretic properties, whereas sweet clover was found to increase venous reflux, better termed “venous return” (Fleming 2000). Both butcher’s broom, which is Class 1, and sweet clover appear to be safe when used as recommended (McGuffin et al. 1997; Fleming 2000).

Ginkgo (Ginkgo biloba) has been used orally in China for centuries and has come to use more recently in Europe and the United States for treating numerous conditions, including heart disease, asthma, vertigo, tinnitus, impotence, cerebral and vascular insufficiency, peripheral vascular disorders, dementia, and other conditions. Research indicates that ginkgo promotes vasodilation, thereby improving many of these conditions. Most research on ginkgo focuses on cerebral insufficiency and claudication. Studies suggest ginkgo may be more useful for these vascular disorders than for CVI (Hadley and Petry 1999; Peirce, Fargis, and Scordato 1999). Caution should be used when ginkgo is taken orally, as there have been reports of subarachnoid and intracerebral hemorrhage, as well as increased bleeding time (Fleming 2000), although it is Class 1 (McGuffin et al. 1997).

Several double-blind trials conducted in France studied the effects of grape seed (Virus vinifera) extract on CVI. Grape seed extract contains oligomeric proanthocyanidins, which are bioflavonoids demonstrated to be beneficial by strengthening capillaries. Dosages in the studies varied from 50 mg orally once a day to 100 mg thrice a day. No serious adverse effects were reported (Fleming 2000).

Horse chestnut seed extract (HCSE) is one of the most researched herbal alternatives. Horse chestnut (Aesculus hippocastanum) contains the plant compounds known as “terpenes,” with the most active component being aescin (Peirce, Fargis, and Scordato 1999). The mechanism of action appears to be related to the inhibition of leukocyte activation, an important pathophysiological mechanism contributing to CVI. Aescin is also thought to decrease vascular leakage by inhibiting elastase and hyaluronase, which are involved in proteoglycan degradation at the capillary endothelium (Pittler and Ernst 1998). Many double-blind, randomized trials of orally administered HCSE have been conducted on patients with CVI. It was demonstrated that HCSE decreases lower-leg volume as well as calf and ankle circumference. Patients also showed decreased symptoms such as fatigue, tenderness, and pruritus. One study showed the relative equivalency of using HCSE compared with grade II compression stockings for treatment of CVI (Diehm 1996). Most of the studies achieved statistically significant results for treatment of CVI with doses of HCSE containing 100–150 mg of aescin per day, most often taken as 50 mg twice a day. Adverse effects reported were minimal and included gastrointestinal tract discomfort, dizziness, headache, and pruritus. Rates of reported adverse effects were from 0.9% to 3.0% and in several studies were not statistically different from rates of adverse effects observed with placebo. Although there are no long-term studies of orally administered HCSE in treating CVI and its sequelae, these results seem promising and offer patients a safe alternative to compression stockings. In Europe, HCSE has also been used in the form of a topical gel, lotion, or ointment to reduce inflammation and discomfort associated with varicose veins, phlebitis, and hemorrhoids (Peirce, Fargis, and Scordato 1999).

It must be noted that the seeds of horse chestnut tree are poisonous and must be specially prepared by a reputable manufacturer to remove all toxins. Once the toxins have been removed, it is considered relatively safe when taken orally. There has been one case report of drug-induced lupus attributed to Venocuran (manufactured by Knoll AG, Ludwigshafen, Germany), a drug for venous insufficiency containing HCSE (Peirce, Fargis, and Scordato 1999). Contact dermatitis has occasionally been reported when HSCE was used topically (Bisset and Wichtl 2001).

Witch hazel (H. virginiana) contains considerable amounts of tannin (see the details of preparation in Section 18.3.1), making it a useful astringent. It has been used topically to soothe inflammation of the skin and mucous membranes in disorders such as varicose veins and hemorrhoids. Animal research suggests that witch hazel extract has local styptic and vasoconstrictive effects. The alcohol fluid extract has also been found to cause venous constriction in rabbits. It is often used orally for CVI in Europe. Although it appears safe when taken orally and is included in Class 1, the efficacy of such treatment has not been studied well in humans (McGuffin et al. 1997; Blumenthal et al. 1998). Various TCM herbal mixes for treating stasis dermatitis are listed by Xu (2004).

18.3.5. Dermatitis

Arnica is derived from the dried flowers of Arnica montana or other arnica species. Although oral administration can cause severe health hazards even in small amounts, preparations for external use are very safe and effective. Arnica has been used for centuries as an anti-inflammatory drug to rub into sore muscles and joints, bruises, insect bites, boils, inflamed gums, acne eruptions, and hemorrhoids. It is also an ingredient found in many seborrheic dermatitis and psoriasis preparations. It is approved by Commission E for topical treatment of skin inflammation (Blumenthal et al. 1998). When used as a compress, 1 tablespoon (tbsp; 15 mL) of tincture is mixed with 0.5 L of water; if used as an infusion, 2 g of dried arnica is mixed with 100 mL of water. Cream or ointment preparations should contain a maximum of 15% arnica oil or 20–25% tincture (Bisset and Wichtl 2001; Peirce, Fargis, and Scordato 1999). The active ingredients of arnica are the sesquiterpene lactones such as helanalin, 11α,13-dihydrohelenalin, chamissonolid, and their ester derivatives. These components reduce inflammation by inhibiting the transcription factor nuclear factor κB (NF-κB). The factor NF-κB controls the transcription of many genes, including cytokines such as interleukin (IL)-1, IL-2, IL-6, IL-8, and tumor necrosis factor α, as well as adhesion molecules such as intercellular adhesion molecule 1, vascular cellular adhesion molecule 1, and endothelial leukocyte adhesion molecule 1. It also inhibits many genes responsible for antigen presentation and activation of cyclooxygenase 2 (Lyss et al. 1997). There are reports of contact dermatitis caused by arnica. There are also several reports of irritation when arnica is used at stronger concentrations or for longer periods than are recommended. It is not recommended for use on open wounds or broken skin, and is included in Class 2d (McGuffin et al. 1997). It is important to buy arnica from a reputable source, because it is a protected species in some countries and other plants are substituted fraudulently.

German chamomile (Matricaria recutita), a member of the daisy family, has been used for centuries, both internally and externally, for treating many conditions, especially gastrointestinal tract symptoms, oral or skin inflammation, as well as dermatitis. A tea is made by using 2–3 teaspoons (tsp; 10–15 mL) of dried flowers per cup of water and is taken internally or used as a compress. Topical preparations with cream or ointment bases are also used and researched in Germany (Bisset and Wichtl 2001). Studies have demonstrated that topical chamomile is comparable with 0.25% hydrocortisone and shows improvement in sodium lauryl sulfate–induced contact dermatitis (Brown and Dattner 1998). A small double-blind trial found that chamomile significantly decreased the surface area of wounds and, in animal studies, healing time was found to be reduced with chamomile. Chamomile also shows in vitro antimicrobial activities (Peirce, Fargis, and Scordato 1999). The main adverse effect reported is allergic contact dermatitis. Chamomile is considered safe to use topically and orally, and is included in Class 1 (McGuffin et al. 1997). The anti-inflammatory, wound-healing, and antimicrobial effects of German chamomile are attributed to an essential blue oil that contains sesquiterpene alcohol, α-bisabolol, chamazulene, and flavinoids. These substances showed anti-inflammatory and antispasmodic properties in animal studies, due in part to the inhibition of cyclooxygenase and lipoxygenase in vitro. The flavinoids also act by inhibiting histamine release from antigen-stimulated human basophilic polymorphonuclear leukocytes (Brown and Dattner 1998). The substance α-isabolol also demonstrated promotion of granulation tissue in wound healing (Peirce, Fargis, and Scordato 1999). Bittersweet nightshade (S. dulcamara) and brewer’s yeast (S. cerevisiae) are thought to have similar anti-inflammatory and antibacterial effects.

Herbal medicine derived from TCM for the treatment of atopic dermatitis has been reported effective by British studies. In TCM, the body is treated as a whole and the aim of therapy is to restore harmony to the functions of the body (Atherton et al. 1992). A mixture of various herbs is individually formulated for a patient (Sheehan et al. 1992), making it difficult to undertake randomized, controlled trials. Two randomized, placebo-controlled crossover trials were performed in England to study the effects of standardized oral herbal TCM in the treatment of atopic dermatitis cases for which traditional Western therapy had failed (Sheehan et al. 1992; Sheehan and Atherton 1992; Armstrong and Ernest 1999). The investigators were aided by a Chinese physician who created a standardized mixture of 10 herbs useful for treating atopic dermatitis characterized by erythema, lichenification, and plaques of dermatitis in the absence of active exudation or clinical infection. The 10 herbs used were Potentilla Chinensis, Class 1; Tribulus terrestris; Rehmannia glutinosa, Class 2d; Lophatherum gracile; Clematis armandii, Class 1; Ledebouriella saseloides, Class 1; Dictamnus dasycarpus; Paeonia lactiflora, Class 1; Schizonepeta tenuifolia; and Glycyrrhizia glabra, Class 1 (Sheehan and Atherton 1992; McGuffin et al. 1997). These herbs were placed in sachets and boiled to make a decoction that was orally administered daily as a tea. The placebo consisted of a decoction made from several herbs with similar smells and tastes that have no known efficacy in the treatment of atopic dermatitis. The first study with 37 children demonstrated a median decrease in erythema score of 51.0% in the treatment group compared with only a 6.1% improvement in the placebo group. The percentage surface involvement also decreased by 63.1% and 6.2% for the herb-treated and placebo groups, respectively. In this initial study, no serious adverse effects were found. These 37 children were offered continued treatment with the TCM herbal mixture and were then followed up for 1 year (Sheehan and Atherton 1994). Eighteen children completed the year of treatment and showed 90% reduction in eczema activity scores. The children who withdrew from the study did so because of lack of further response to treatment, unpalatability of the tea, or difficulty in preparation of the treatment. By the end of 1 year, seven patients were able to discontinue therapy without relapse. Asymptomatic elevation of aspartate aminotransferase level was noted in two patients, the levels returning to normal after discontinuing treatment. No serious adverse effects were observed. The design was similar in the other study that involved 31 adult patients with atopic dermatitis (Sheehan et al. 1992). The decrease in erythema and surface damage was statistically superior in the herb-treated group compared with the placebo group. There was also subjective improvement in itching and sleep. These patients also were followed up for 1 year, with reports of continued improvement and no serious adverse effects, although the patients who discontinued treatment noted a relapse in their condition (Sheehan and Atherton 1994). Although the sample sizes were limited, initial results were promising for patients for whom standard therapy had failed. The main limiting issue seemed to be the taste and the preparation of the decoction. It should be emphasized that although no serious adverse effects were noted in this study, careful monitoring of complete blood cell count and liver function is recommended, as liver failure and even death have been reported with these TCM herbs when baseline laboratory values were not followed (Graham-Brown 1992; Mostefa-Kara et al. 1992; Koo and Arain 1998). It is known that the specific herbs used in these studies have anti-inflammatory, antibacterial, antifungal, antihistaminic, immunosuppressant, and corticosteroid-like effects. A few of the ingredients are also smooth muscle relaxants, and inhibit the platelet-activating factor. Several studies have attempted to elucidate the mechanism of action of this group of 10 herbs (Zemophyte, manufactured by Phytotech Limited, Godmanchester, England) in treating atopic dermatitis. Patients with atopic dermatitis are known to have elevated levels of the low-affinity IgE receptor CD23 expressed on circulating monocytes. In studies of IL-4-induced CD23 expression on monocytes, there appeared to be a reduction in CD23 expression when the cells were exposed to the aqueous herb extracts (Latchman et al. 1994, 1996). Another study examined immunologic markers for T cells, macrophages, Langerhans cells, and low-affinity and high-affinity IgE receptors in biopsy specimens of lesional skin treated with Zemophyte compared with biopsy specimens of nonlesional skin (Xu et al. 1997). The investigators found clinical improvement similar to that seen in the aforementioned Sheehan studies, and also found that the improvement was associated with a statistically significant reduction in CD23 antigen-presenting cells. However, an attempt to replicate the Zemophyte double-blind randomized placebo-controlled study in Hong Kong failed to achieve a statistically significant effect of Zemophyte over placebo (Fung et al. 1999). A different TCM herbal mixture called PentaHerbs formula, with Paeonia suffruticosa root bark, Class 1; Phellodentron chinensis bark, Class 2b; Lonicera japonica flower, Class 1; Mentha haplocalux aerial part, Class 1; and Atractylodes lancea rhizome Class 1 in a ratio of 2:2:2:1:2, known clinically to be useful in the management of atopic dermatitis, was tested on rat peritoneal mast cells and found to suppress histamine release and prostaglandin D2 synthesis (Chan et al. 2008). The bark of the birch tree (Betula platyphylla var. japonica), which is used to treat atopic dermatitis, was studied in NC/Nga mice. It decreased scratching and skin inflammation, as well as decreasing IgE and IL-4 messenger ribonucleic acid (mRNA) levels, suggesting that it suppresses the T-helper 2 cellular response (Kim et al. 2008). Other TCM herbal mixes for dermatitis are listed by Xu (2004).

Jewelweed (Impatiens biflora) is alleged to be useful topically for treating poison ivy contact dermatitis, but research results are conflicting. In one study, treatment with jewelweed was found to be comparable with standard treatment for poison ivy contact dermatitis, and in 108 of 115 patients studied, the symptoms cleared within 2–3 days (Lipton 1958). However, in another study, jewelweed extract failed to decrease symptoms of poison ivy dermatitis (Guin and Reynolds 1980). In yet another study, no prophylactic effect of jewelweed in treating poison ivy dermatitis was reported (Long, Ballentine, and Marks 1997). Jewelweed has been said to be most effective if applied to the area where the poison ivy touched as soon as possible after contact, but this aspect was not addressed by the aforementioned studies. There have been no reports of topical jewelweed causing adverse effects (Peirce, Fargis, and Scordato 1999, 365).

Several herbs contain a substance called “mucilage,” which is useful topically to soothe and act as an emollient on skin. Heartseases (Viola tricolor), Class 1; marshmallow (Althea officinalis); English plantain (Plantago lanceolata), Class 1; fenugreek (Trigonella foenum-gaecum), Class 2b; mullein (Verbascum thapsus), Class 1; slippery elm (Ulmus fulva), Class 1; and flax (Linum usitatissimum) contain mucilages, which act as emollients on and soothe the skin. Mucilage quickly swells into a gooey mass when exposed to water, thereby ameliorating dry or mildly inflamed skin. Mucilage also dries as a mild adhesive and can be used as an herbal bandage for minor wounds (McGuffin et al. 1997; Peirce, Fargis, and Scordato 1999; Fleming 2000).

Oats (Avena sativa) have been used topically in baths for hundreds of years for their soothing and antipruritic properties, and they are approved for this use by the German regulatory authority Commission E and are listed as Class 1 (McGuffin et al. 1997; Fleming 2000; Bisset and Wichtl 2001). Colloidal oatmeal turns to a gooey sticky mass when mixed with liquid which can be used to coat the skin and sealing in moisture. This soothing and moisturizing property is attributed to the gluten content of the plant. This can be useful in treating atopic dermatitis as well as idiopathic pruritus of the elderly.

Pansy flower (V. tricolor hybrids) infusion is recommended as a nontoxic treatment for seborrheic dermatitis, especially in infants. The infusion is made by mixing 1–2 tsp of flowers per cup of water and is used as a wet dressing. Salicylic acid in concentrations of about 0.3% appears to be the active ingredient. It also contains saponins and mucilage, which have softening and soothing effects. No adverse effects have been reported with topical use, and pansy is included in Class 1 (McGuffin et al. 1997; Peirce, Fargis, and Scordato 1999).

In treating dermatitis, tannins used topically act by coagulating the surface proteins of cells and exudates, thereby reducing permeability and secretion. The precipitated proteins also form a protective layer on the skin (Brown and Dattner 1998). Tannins may also have antimicrobial properties. Tannins found in agrimony (Agrimonia eupatoria), Class 1; jambolan bark (Syzygium cumini), Class 1; oak bark (Quercus robur), Class 2d; English walnut leaf (Juglans regia), Class 2d; Labrador tea (Ledum groenlandicum); goldenrod (Solidago spp.), Class 2d; lady’s mantle (Alchemilla spp.), Class 1; lavender (Lavandula angustifolia), Class 1; mullein (Verbascum thapsus), Class 1; rhatany (Krameria spp.), Class 1; Chinese rhubarb (Rheum officinale), Class 2b, 2c, 2d; yellow dock (Rumex crispus), Class 2d; witch hazel bark (H. virginiana), Class 1; and St. John’s wort (Hypericum montana), Class 2d, act as astringents. Oat straw (A. sativa) included in Class 1 is also approved for its soothing and antipruritic qualities (McGuffin et al. 1997; Blumenthal et al. 1998; Peirce, Fargis, and Scordato 1999; Fleming 2000; Bisset and Wichtl 2001). One study showed that a witch hazel extract in a phosphatidyl choline base was less effective in reducing erythema from ultraviolet (UV) radiation and cellophane tape stripping in 24 healthy patients than 1% hydrocortisone (Korting et al. 1993). In another clinical trial, one group with atopic dermatitis (n = 36) and another group with contact dermatitis (n = 80) compared witch hazel extract with control. In the atopic group, the witch hazel was slightly superior in reducing inflammation and itching. There are also anecdotal reports of witch hazel’s usefulness in treating atopic dermatitis (Brown and Dattner 1998).

18.3.6. Herpes Simplex

Lemon balm (Melissa officinalis) is a lemon-scented member of the mint family. An essential oil can be steam-distilled from the cut leaves. Topical uses include treatment of herpes simplex and minor wounds. In a randomized, double-blind trial of 116 patients with herpes simplex lesions, 96% reported complete clearing of lesions at day 8 after using 1% balm extract cream five times a day (Wobling and Leonhardt 1994). In another trial where balm extract was placed on lesions within 72 hours of the onset of symptoms, the size of the lesions and healing time were found to be statistically better in the group treated with balm (Brown and Dattner 1998). Tannin and polyphenols appear to be responsible for the antiviral effect of the balm (Peirce, Fargis, and Scordato 1999). Balm is included in Class 1, and is very safe to use both topically and orally (McGuffin et al. 1997; Peirce, Fargis, and Scordato 1999).

Other herbal preparations that have reported in-vitro activity against herpes simplex include Echinacea spp., sweet marjoram, peppermint, and propolis, although clinical studies for the latter three have not yet been performed (Peirce, Fargis, and Scordato 1999). A small, randomized, placebo-controlled crossover clinical trial found no statistically significant differences between Echinacea extract of 800 mg twice per day for 6 months and placebo controls in treating recurrent genital herpes (Basch et al. 2005). The TCM herbal mixtures for treating herpes simplex are listed by Xu (2004).

18.3.7. Herpes Zoster

Capsaicin, the main ingredient in cayenne pepper (Capiscum frutescens, Class 1 internally but Class 2d externally; McGuffin et al. 1997) is available as a cream for the treatment of postherpetic neuralgia. It is applied four or five times a day and initially causes a burning sensation. With continued use, it depletes substance P in the regional peripheral nerves, reducing pain. In China, herpes zoster is commonly treated topically with hibiscus (Hibiscus sabdariffa; Fleming 2000). Hibiscus has been proved to be a very safe Class 1 herb, both topically and orally (McGuffin et al. 1997). The TCM herbal mixtures for herpes zoster are listed by Xu (2004).

Herpes zoster and postherpetic neuralgia have been treated with a topical licorice (Glycyrrhiza glabra, G. uralensis) Class 1 gel preparation (Lininger 2000). Glycyrrhizen, one of the active components of licorice, has been demonstrated to inhibit the replication of varicella zoster in vitro (Baba and Shigeta 1987). There are so far no clinical studies to support this. Topical use is reported to be very safe, but care should be taken when it is taken orally as it is included in both Classes 2b and 2d (McGuffin et al. 1997).

18.3.8. Hyperhidrosis

By precipitating surface proteins, topical tannins can reduce the openings of sweat ducts and thus reduce sweating locally. Tannins also have antimicrobial properties that help to reduce odorous bacterial by-products (van Wyk and Wink 2004). See Section 18.3.5 for information about specific sources of tannins. Black tea also contains tannins.

18.3.9. Pruritus

Camphor is derived from the camphor tree (Cinnamomum camphora) Classes 2b and 2d distillate of the wood (McGuffin et al. 1997, 30). It is toxic in large doses. As an antipruritic, it can be added to lotions or creams at one-half percent. Menthol is derived from Japanese mint (M. arvensis), which is included in Class 1 (McGuffin et al. 1997). It has a cooling, antipruritic, and antibacterial effect. Lotions and creams typically contain 1–5% essential oil. As noted in Section 18.3.5, oats also have a soothing, antipruritic effect.

Tars derived from birch (Betula spp.), beech (Fagus spp.), or juniper (Juniperus spp.) trees (van Wyk and Wink 2004) are antipruritic and antiproliferative. They are used in a 5–10% concentration in creams, gels, and soaps. They are photosensitizing compounds, and judicious exposure to sunlight can be beneficial.

18.3.10. Psoriasis

Aloe vera (Aloe vera), which is Class 1 internally and Class 2d externally (McGuffin et al. 1997), has been used for centuries in wound healing and was recently found to be a potential treatment for psoriasis. In a double-blind placebo-controlled study, 60 patients with slight to moderate plaque psoriasis were treated topically with either 0.5% hydrophilic aloe cream or placebo. The aloetreated group showed statistically significant improvement (83.3%) compared with the placebo group (6.6%). There were no adverse effects reported in the treatment group (Syed et al. 1996).

Capsaicin is the main ingredient in cayenne pepper (C. frutescens), which is Class 1 internally but Class 2d externally (McGuffin et al. 1997); it has also been studied for the treatment of psoriasis. In vitro, capsaicin was found to inhibit phorbol ester-induced activation of transcription factors NF-κB and AP-1 (Surh et al. 2000). Two trials showed that 0.025% cream used topically is effective in treating psoriasis. The first study showed a significant decrease in scaling and erythema during a 6-week period in 44 patients with moderate and severe psoriasis (Bernstein et al. 1986). The second was a double-blind study of 197 patients in whom psoriasis was treated with the capsaicin cream four times daily for 6 weeks, with a significant decrease in scaling, thickness, erythema, and pruritus (Ellis et al. 1993). The main adverse effect reported was a brief burning sensation at the application site. Capsaicin is contraindicated on injured skin or near the eyes, and the German authority Commission E suggests it should not be used for more than 2 consecutive days, with a 14-day lapse between applications.

A survey of patients with psoriasis at a large university dermatology practice revealed that 51% of patients used one or more alternative therapeutic modalities (Fleischer et al. 1996). This is consistent with previous Norwegian surveys of patients with psoriasis (Jensen 1990). Herbal therapy is one of the most frequently chosen alternative therapies. Psoriasis has been treated for centuries with herbal preparations, both topical and oral. There are many herbal preparations composed of furocoumarins, which act as psoralens when combined with ultraviolet A (UV-A, 320–400 nm). Furocoumarins derived from Ammi majus and related plants that produce 8-methoxy-psoralen when applied topically or taken orally intercalate with DNA. Further, when coupled with exposure to UV-A from the sun or a an ultraviolet light-box, the photoactivation causes cross-linkages with the thymine in the DNA, inducing cell death (van Wyk and Wink 2004). This, in turn, inhibits hyperproliferation in psoriatic lesions.

One commonly used TCM, Radix Angelicae dahurica, included in Class 1 (McGuffin et al. 1997), contains the furocoumarins imperatorin, isoimperatorin, and alloimperatorin. In a study involving 300 patients with psoriasis, this TCM, taken orally, was combined with UV-A therapy and was compared with the standard treatment of psoralen—UV-A with methoxsalen. The efficacy of the two treatments was equivalent; however, there were fewer adverse effects such as nausea and dizziness in the group treated with TCM and UV-A (Koo and Arain 1998). In addition, there are topical preparations made from herbs that show systemic efficacy against psoriasis, but are too toxic when given systemically (Ng 1998). Topical TCM of the plant Camptotheca acuminata in an open trial including 92 patients with psoriasis found that this TCM was statistically more effective than 1% hydrocortisone. A disadvantage was that allergic contact dermatitis was seen in 9–15% of the patients in the TCM group. Comparison of TCM mixtures in clinical trials is difficult, because the mixture of herbs prescribed varies individually depending on the subtype of psoriasis (“blood-heat” type, “blood deficiency dryness” type, and “blood stasis” type), which is determined in TCM by many findings, including lesions of psoriasis, the pulse, and the condition of the tongue (Koo and Arain 1998). Some types of TCM may act in part on the microcirculation of the psoriatic lesion (Zhang and Gu 2007). Additional TCM herbal mixtures for psoriasis are listed by Xu (2004).

About 5% curcumin is present in turmeric (Curcuma longa), which is included in Classes 2b and 2d (McGuffin et al. 1997; see also Chapter 13 on turmeric). Turmeric has been used for centuries in India to provide glow and luster to the skin. It has antimicrobial, antioxidant, astringent, and other useful effects that help to heal wounds and reduce scarring (Chaturvedi 2009). In vitro, the purified turmeric extract curcumin has been found to inhibit phorbol ester-induced activation of transcription factors NF-κB and AP-1 (Surh et al. 2000). The resulting suppression of phosphorylase kinase activity correlates with the resolution of psoriasis when curcumin is applied topically to the lesions (Heng et al. 2000). Microencapsulation of curcumin reduces the yellow staining produced by application of topical curcumin on the skin, while prolonging the bioavailability of curcumin (Aziz, Peh, and Tan 2007).

Tars have been used for centuries to treat psoriasis. Tars derived from birch (Betula spp.), beech (Fagus spp.), or juniper (Juniperus spp.) trees (van Wyk and Wink 2004) are antipruritic and antiproliferative. They are used in a 5–10% concentration in creams, gels, and soaps. They are photosensitizing compounds, so judicious exposure to sunlight can be beneficial, or they can be used in conjunction with ultraviolet B (UV-B; 250–320 nm) or narrowband UV-B (311 nm).

18.3.11. Psychosomatic

Depression and anxiety can cause skin problems. Kava kava (Piper methysticum) has moderate anxiolytic effects, but its use is not recommended due to its potential hepatotoxicity. It is included in Classes 2b, 2c, and 2d (McGuffin et al. 1997). Lavender oil aromatherapy (Lavendula spp.) has been demonstrated to produce significant reduction in anxiety. This may in part be a conditioned response, and it is important that the first exposure to lavender oil is a pleasant and relaxing one. It is Class 1 (McGuffin et al. 1997). Lemon balm (M. officinalis) is approved by the German authority Commission E for treating nervousness and insomnia. It is also Class 1 (McGuffin et al. 1997.) Magnolia bark (Magnolia obovata) has moderate anxiolytic effects. It contains honokiol and magnolol, which have antioxidant and anti-inflammatory (Kuribara, Stavinoha, and Maruyama effects. It is Class 2b (McGuffin et al. 1997). Passion flower (Passiflora incarnata) is approved by Commission E for treating nervousness and insomnia. It is Class 1 (McGuffin et al. 1997). St. John’s wort (H. perforatum) is approved by Commission E for treating depression. It is helpful for treating mild to moderate depression but not for severe depression (Linde et al. 1996). It has significant interactions with the metabolism of a number of other drugs by inducing cytochrome P450 isoform 3A4, and is Class 2d (McGuffin et al. 1997). Valerian (Valariana spp.) is approved by Commission E for treating insomnia caused by nervousness. It is Class 1 (McGuffin et al. 1997).

18.3.12. Scabies

Anise (Pimpinella anisum) seeds are a source of an essential oil that displays antibacterial and insecticidal activity in vitro and is used topically to treat scabies and head lice. It should not be used in pregnancy and is Class 2b (McGuffin et al. 1997). Neem (Azadirachta indica) is indigenous to India, and every part of the plant is used medicinally. In a study of more than 800 villagers in India, a paste of neem and turmeric applied topically was reported to treat chronic ulcers and scabies (Peirce, Fargis, and Scordato 1999). It seems to be safe for use in adults, but can be poisonous to children (Peirce, Fargis, and Scordato 1999). Numerous other herbs have been used for centuries in India and China to treat scabies (Fleming 2000).

18.3.13. Skin Cancer

Red ginseng (Panax ginseng) is a classic TCM. In a recent study, red ginseng extracts used topically were found to inhibit chemically induced skin tumors in mice. This is thought to be due to the immuno-modulating properties of red ginseng (Cheng, Lin and Lei et al. 1998). It is Class 2d (McGuffin et al. 1997).

Propolis is a resinous material gathered by honeybees from the buds and bark of certain plants and trees. Propolis has been used for centuries for its antimicrobial, anti-inflammatory, analgesic, and antitumor effects, which are thought to result from the flavinoid and related phenolic acids components. A tumoricidal component, clerodane diterpenoid, has also been isolated. This compound was studied regarding its topical effects on skin tumorigenesis in mice. Clerodane diterpenoid appeared to reduce the incidence of chemically induced dysplastic papillomas by inhibiting the synthesis of DNA in a de novo pathway and by suppressing the growth of tumors by decreasing DNA synthesis in a salvage pathway (Mitamura et al. 1996).

Rosemary (Rosmarinus officinalis) extract is reputed to have antioxidant activity. A methanol extract of the leaves was evaluated for its effects on skin tumors in mice. It was found that topically applied rosemary inhibited induction and promotion of skin tumors in mice treated with known chemical carcinogens. Although the exact mechanism of action is still under study, it appears that several components of the extract are important in this process. This finding suggests that it was not the antioxidant properties alone that were beneficial in the prevention of skin tumors (Huang et al. 1994). Rosemary should not be used in pregnancy as it is a Class 2b herb (McGuffin et al. 1997).

Silymarin is a flavinoid isolated from milk thistle (Silybum marianum), and is approved by the German Commission E for treating liver disease because of its antioxidant properties. An experiment was performed to assess whether this antioxidant effect would protect against tumor promotion. Topically applied silymarin was found to possess highly protective effects against chemically induced skin tumor promotion in mice. This may involve inhibition of promoter-induced edema, hyperplasia, and proliferation, as well as the oxidant state (Lahiri-Chatterjee et al. 1999). These results are promising, yet more research involving human models is needed. Silymarin is safe to use topically and orally when used appropriately, and is Class 1 (McGuffin et al. 1997).

Tea is manufactured from the leaf and bud of Camellia sinensis (see also Chapter 12 on tea). The majority of tea consumed worldwide is in the form of black tea, which is Class 2d (McGuffin et al. 1997). Green tea has been found in several mouse models to have anti-inflammatory and antitumorigenic properties. The polyphenolic constituent (–)-epigallocatechin-3-gallate is thought to be the active ingredient. Numerous studies of green tea and skin cancer were reviewed (Katiyar, Ahmad, and Mukhtar 2000). It was found that topical application or oral consumption of green tea protects against inflammation, chemical carcinogenesis, and photocarcinogenesis. Green tea demonstrated the blocking of many mediators in the inflammatory process important in the early steps of skin tumor promotion. It also appears that there is inhibition of biochemical markers of chemical carcinogenesis, inhibition of UV-induced oxidative stress, and prevention of UV-induced immunosuppression (Katiyar, Ahmad, and Mukhtar 2000) as a result of action of green tea. Green tea also protects against psoralen UV-A-induced photochemical damage to the skin (Zhao Jin and Yaping et al. 1999). Many cosmetics and skin care products have been recently supplemented with green tea, but more research in humans is needed to understand the true benefits. Black tea may also play a role in the prevention of skin tumors. It appears that theaflavins are the components active in chemoprevention (Nomura et al. 2000). Several studies provide evidence that topical application of the constituents of black tea can decrease UV-B-induced erythema, inhibit tumor initiation, and act as an antitumor promoter (Javed, Mehrotra, and Shukla 1998; Zhao Zhang and Jin et al. 1999). Oral administration of black tea was also found to inhibit tumor proliferation and promote tumor apoptosis in nonmalignant and malignant skin tumors (Lu et al. 1997). A survey of older patients compared tea consumption and history of squamous cell carcinoma. There was a lower risk of squamous cell carcinoma in patients who regularly consumed hot black tea than in nonconsumers (Hakim, Harris, and Weisgerber 2000). Different studies comparing the effectiveness of black and green teas in protecting against UV-induced skin tumors give conflicting findings as to which is more beneficial (Wang et al. 1994; Huang et al. 1997; Record and Dreosti 1998; Lou et al. 1999). Caffeinated teas seem to be more protective than decaffeinated teas, and caffeine by itself has some inhibitory effects on UV-B-induced carcinogenesis (Wang et al. 1994; Huang et al. 1997; Lou et al. 1999).

18.3.14. Verruca Vulgaris And Condyloma Accuminata

Podophyllin, used to treat condyloma acuminata, is extracted from the root of the American mayapple (Podophyllum peltatum; Fleming 2000). It should not be used during pregnancy and is Class 2b externally and toxic internally (McGuffin et al. 1997). Commission E approves bittersweet nightshade (S. dulcamara), Classes 2b and 2c, and oat straw (A. sativa), Class 1, for the treatment of common warts (McGuffin et al. 1997; Fleming 2000). Calotropis (Calotropis procera) is used in India, and greater celandine (Chelidonium majus), Classes 2b, 2c, and 2d (McGuffin et al. 1997, 28), is used in China for the treatment of warts (Fleming 2000). Bittersweet nightshade and celandine should also be avoided in pregnancy and while breast-feeding (Fleming 2000).

18.3.15. Vitiligo

Ginkgo (G. biloba) was found to be effective in a small study for treating limited, slowly spreading vitiligo (Parsad, Pandhi, and Juneja 2003). Caution should be used when ginkgo is taken orally, as there have been reports of subarachnoid and intracerebral hemorrhage, as well as increased bleeding time (Fleming 2000); but the herb is included in Class 1 (McGuffin et al. 1997).

Psoralens, such as the furanocoumarins derived from A. majus and related plants that produce 8-methoxy-psoralen, when applied topically or taken orally, intercalate with DNA. As noted in Section 18.3.10, with photoactivation they can induce cell death (van Wyk and Wink 2004). By thus reducing inflammatory cells while stimulating melanogenesis, the treatment often induces repigmentation of vitiliginous skin.

18.3.16. Wounds And Burns

Aloe vera (A. vera) leaves produce a gel and a juice or latex. The gel is obtained from the central core of the leaf and has been used topically for centuries for the treatment of wounds and burns. The juice or latex is a bitter yellow fluid extracted from the inner leaf skin and is generally sold dried as a powder that has very potent laxative effects (Peirce, Fargis, and Scordato 1999). Several case reports and animal studies demonstrate that aloe vera decreases burning, itching, and scarring associated with radiation dermatitis (Klein and Penneys 1988). Aloe vera was also found to accelerate healing of chronic leg ulcers, surgically induced wounds, and frostbite. The mechanism of action has been studied in vivo in animal studies. Aloe vera decreases thromboxane A2, thromboxane B2, and prostaglandin 2α, which cause vasoconstriction and platelet aggregation. By increasing dermal perfusion, tissue loss from ischemia is reduced (Klein and Penneys 1988). In vitro studies have also demonstrated a carboxypeptidase that inactivates bradykinin, decreasing pain at the treatment site (Fujita and Shosike 1976). Salicylic acid present in aloe vera acts as an analgesic and anti-inflammatory agent by inhibiting prostaglandin production (Robinson, Heggers, and Hagstrom 1982). Magnesium lactate is also present in aloe vera and is thought to be antipruritic by inhibiting histidine decarboxylase, which controls the conversion of histidine to histamine in mast cells (Klein and Penneys 1988). Reduction in inflammation is also thought to result from the immunomodulatory properties of the gel polysaccharides present, especially the acetylated mannans (Reynolds and Dweck 1999). Aloe vera also demonstrates bactericidal and antifungal activity in vitro. The main adverse effect of topical aloe vera gel is that it causes allergic contact dermatitis. There are also reports of delayed healing after laparotomy or a Cesarean section. Taken orally, aloe vera is considered very safe when used properly. It is Class 1 internally and Class 2d externally (McGuffin et al. 1997).

Asiaticoside in low concentrations has been found to enhance the healing of burn wounds, with evidence suggesting that enhanced angiogenesis may occur as a result of stimulation of vascular endothelial growth factor production (Kimura et al. 2008).

Honey has been used topically for centuries to assist healing of wounds, including burns, decubitus ulcers, and infected wounds (Greenwood 1993). It has been found in vitro to have antibacterial and antifungal activity against organisms that commonly infect surgical wounds (Efam and Udoh 1992). A study was performed on nine infants with large, open, culture-positive postoperative wound infections for whom standard treatment consisting of appropriate intravenous antibiotics and cleansing with chlorhexidine for more than 14 days had failed. The wounds were then treated with 5–10 mL of fresh, unprocessed honey twice a day. There was marked clinical improvement by day 5, and by day 21, the wounds were all closed, clean, and sterile (Vardi et al. 1998). In a randomized controlled trial, honey-impregnated gauze was compared with a polyurethane film (OpSite, manufactured by Smith & Nephew, North Humberside, England) for partial-thickness burns. The honey-treated wounds healed statistically earlier, with a mean of 10.8 days versus 15.3 days for film-treated wounds and with equal numbers of complications such as infection, excessive granulation, and contracture compared with the polyurethane-film-treated wounds (Subrahmanyam 1993). The wound-healing properties of honey are believed to result from the debriding properties of the enzyme catalase, absorption of edema due to honey’s hygroscopic properties, its ability to promote granulation and reepithelialization from the wound edges, and its antimicrobial properties (Efam 1988). There have been no reports of significant adverse effects, although there are reports of contact dermatitis to honey (Efam 1988).

Marigold (Calendula officinalis) has been used topically since ancient times and is approved by the German regulatory authority Commission E as an antiseptic and for wound healing (Bisset and Wichtl 2001). A topical preparation of marigold continues to be recommended for the treatment of wounds, ulcers, burns, boils, rashes, chapped hands, herpes zoster, and varicose veins. Marigold gargles are used for mouth and throat inflammation (Peirce 1999). Marigold is also widely used as a topical treatment for diaper dermatitis and other mild skin inflammations (Brown and Dattner 1998). The treatment consists of an application several times a day of an ointment or a cream made by mixing 2–5 g of the flower heads with 100 g of ointment. A gargle or lotion is made by mixing 1–2 tsp (5–10 mL) of tincture with 0.25–0.5 L of water (Peirce 1999). The main adverse event is allergic contact dermatitis. No serious adverse effects have been reported, and it is considered safe to use both topically and orally. It is Class 1 (McGuffin et al. 1997). The anti-inflammatory effects of marigold are ascribed to the presence of triterpenoids. In animal studies, Calendula was suggested to stimulate granulation and increase glycoproteins and collagen at wound sites (Brown and Dattner 1998). Marigold also shows in vitro antimicrobial and immune-modulating properties (Peirce 1999).

There are many herbs containing tannins that act as astringents, helping to dry oozing and bleeding wounds. Some of the more commonly reported tannin-containing herbs that may be helpful for the topical treatment of wounds include English walnut leaf, goldenrod, Labrador tea, lavender, mullein, oak bark, rhatany, Chinese rhubarb, St. John’s wort, and yellow dock (see Section 18.3.5 for a list of scientific plant names and ratings of toxicity; Peirce 1999).

18.4. ADVERSE EFFECTS OF HERBAL TH ERAPY

Herbal therapies vary greatly in their safety class ratings. For example, some are consumed as foods and have high safety ratings, whereas others are highly biologically active and toxic and must be used very carefully. The safety classes of the herbs mentioned in this chapter are addressed in each section, and further discussion of interactions of herbal therapies that may be encountered in dermatology is detailed in the remaining sections of the chapter. Many cutaneous reactions to herbal preparations have been reported, with the most common cutaneous adverse event being allergic contact dermatitis. More serious cutaneous reactions have been reported. Two patients developed erythroderma after using topical herbal treatments for psoriasis and atopic dermatitis, and one patient developed Stevens-Johnson syndrome after taking “golden health blood-purifying tablets,” which contained multiple herbs, including red clover, burdock, queen’s delight, poke root, prickly ash, sassafras bark, and Passiflora (Monk 1986). Bullous and nodular lichen planus were reported to be induced by ingestion of native African herbal medicines (Soyinka 1973). A young woman was also described with leukemia-related Sweet syndrome elicited by a pathergic response to topical arnica cream (Delmonte et al. 1998).

Serious systemic adverse effects have been reported with the use of TCM herbal mixtures for the treatment of dermatologic disorders. The most common are hepatotoxic effects. Although most patients recover without serious consequences as long as the medication is stopped, there have been reports of patients with acute liver failure leading even to death. There are also reports of renal failure and agranulocytosis (Graham-Brown 1992; Mostefa-Kara et al. 1992; Koo and Arain 1998). One patient was described with adult respiratory distress syndrome after administration of a TCM, kamisyoyo-san, for seborrheic dermatitis (Shota et al. 1961). A patient was reported with reversible dilated cardiomyopathy after receiving treatment for her atopic dermatitis with a Chinese herbal tea (Ferguson, Chalmers, and Rowlands 1997). There are also reports of Chinese and Indian herbal medicines containing as contaminants heavy metals, such as lead, arsenic, and mercury. Prescription medications have also been found in over-the-counter herbal formulations from other countries. Some herbs are mislabeled or misidentified.

There are many possible drug interactions with herbs and prescription medications. It is crucial for patients to share information about what herbs, supplements, and other over-the-counter remedies they are taking or applying to their skin with their physicians. The most important drug interactions in the dermatologic setting are the immune-upmodulating effects of Echinacea, Astragalus, licorice, alfalfa sprouts, and vitamin E, and zinc may decrease the efficacy of corticosteroids and immunosuppressants (Miller 1998). Some herbs are reported to cause hepatic damage, and they should not be used in combination with medications such as methotrexate. These include many of the ingredients in TCM preparations, as well as Echinacea, chaparral, germander, ragwort, and life root (Ferguson, Chalmers, and Rowlands 1997; Borins 1998). Herbs containing y-linolenic acid, such as evening primrose oil, which has been used for treating dermatitis, psoriasis, and xerosis, lower the seizure threshold; thus, dosages of anticonvulsants may need to be increased (Ferguson, Chalmers, and Rowlands 1997). Rue (Ruta graveolens) and other herbs containing psoralens can cause phototoxic reactions externally on the skin (Eickhorst, Deleo, and Csaposs 2007). In addition to making them aware of the adverse effects already discussed, patients should be counseled on the relative lack of regulation for herbal medicines. There are minimal quality-control requirements currently in place in the United States to ensure the purity, concentration, or safety of herbal supplements. Although herb manufacturers are restricted from making efficacy statements, there are no regulations on claims for what symptoms these herbs can alleviate. In the United States, there are also minimal regulations on which herbs can be restricted in formulations (Shaw 1998).

18.5. CAVEATS CONCERNING HERBAL THERAPY AND DERMATOLOGIC SURGERY

Herbs may affect blood coagulation. A number of medicinal herbs contain coumarin, salicylate, or other platelet-inhibiting substances that can increase the risk of interoperative and postoperative bleeding. Some coumarin-containing herbs include danshen (Salvia miltiorrhiza), dong quai (Angelica sinensis), horse chestnut bark (Aesculius hippocastanum), sweet clover (M. officinalis), sweet vernal (Anthoxanthum odoratum), sweet-scented bedstraw (Galium triflorum), tonka beans (Dipteryx odorata), vanilla leaf (Trilisa odoratissima), and woodruff (Asperula odorata). Salicylate-containing herbs include black cohosh (Cimifuga racemosa), meadowsweet (Spirea ulmaria), poplar bark (Populus spp.), sweet birch bark (Betula spp.), willow bark (Salix spp.), and wintergreen (Gaultheria procumbens). Other platelet function inhibitors include bromelain (Ananas comosus), cayenne (C. frutescens), Chinese skullcap (Scutullaria baicalensis), feverfew (Tanacetum parthenium), garlic (A. sativum), ginger (Zingiber officinale), ginkgo (G. biloba), ginseng (Panex ginseng), onion (A. cepa), papain (Carica papaya), reishi fruit (Ganoderma lucidum), and turmeric (C. longa; Pribitkin 2005).

Herbs may also affect blood pressure. Potentially hypertensive plants include black cohosh, ephedra or ma huang (Ephedra spp.), licorice (G. glabra), and yohimbe (Pausinystalia yohimbe). Potentially hypotensive plants include garlic (Pribitkin 2005).

18.6. RESEARCH NEEDS

Further research into the efficacy, safety, optimal uses, and standardization of herbal remedies is clearly needed. Inhibiting factors in the United States include the nonpatentability of herbal materials in a system in which the typical costs of double-blind testing for Food and Drug Administration (FDA) approval of drugs range in the millions of dollars, requiring patentability for private enterprises to attain a profit. Since herbal remedies currently remain in the category of dietary supplements, a different mechanism of funding for research is needed. The funding for complementary and alternative medicines research provided through the National Institutes of Health is meager compared with private and public funding of research for conventional drugs.

18.7. CONCLUSIONS

Many herbal therapies have been used for centuries, which show good anecdotal results. A few randomized, controlled trials have also demonstrated significant results in the use of herbal therapies for the treatment of dermatologic disorders. Some countries, such as Germany, now require standardization of herbal preparations and specific recommendations as to the use and efficacy of herbs in the treatment of disease. It is important to know what common herbal alternatives exist and which potential adverse effects or interactions can occur to permit more effective counseling of patients.

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