Home > Health A – Z > Toenail Fungus

Toenail Fungus (Onychomycosis)

Fungal infection of a fingernail or toenail.

PubMed Health Glossary
(Source: NIH - National Cancer Institute)

About Toenail Fungus

If your nails become brittle or change color, it might be caused by a fungal nail infection. The big toenails are often affected. Nail fungus is much less common in the fingernails.

Fungal nail infections are very persistent. Because our toenails only grow slowly, treatment generally takes a long time and requires patience. It can take several months until treatment is successful.


A whitish-yellowish or brownish discoloration of the nails is a sign of nail fungus. The nails may become brittle, thicker and change shape. Sometimes they are also painful. The affected part of the nail can detach from the nail bed. Nail fungus is also referred to as "onychomycosis."

The big toenails are particularly affected by nail fungus. In the vast majority of people, the fungus develops at the front or side edge of the nail. It is less common for the infection to spread from the nail root. This kind of infection is most common in people with a severely weakened immune system, possibly following a serious illness. It might also occur after an organ transplantation because people have to take medication that suppresses the immune system... Read more about Toenail Fungus

What works? Research summarized

Evidence reviews

Atopic Eczema in Children: Management of Atopic Eczema in Children from Birth up to the Age of 12 Years

Atopic eczema (atopic dermatitis) is a chronic inflammatory itchy skin condition that develops in early childhood in the majority of cases. It is typically an episodic disease of exacerbation (flares, which may occur as frequently as two or three per month) and remissions, except for severe cases where it may be continuous. Certain patterns of atopic eczema are recognised. In infants, atopic eczema usually involves the face and extensor surfaces of the limbs and, while it may involve the trunk, the napkin area is usually spared. A few infants may exhibit a discoid pattern (circular patches). In older children flexural involvement predominates, as in adults. Diagnostic criteria are discussed in Chapter 3. As with other atopic conditions, such as asthma and allergic rhinitis (hay fever), atopic eczema often has a genetic component. In atopic eczema, inherited factors affect the development of the skin barrier, which can lead to exacerbation of the disease by a large number of trigger factors, including irritants and allergens. Many cases of atopic eczema clear or improve during childhood while others persist into adulthood, and some children who have atopic eczema `will go on to develop asthma and/or allergic rhinitis; this sequence of events is sometimes referred to as the ‘atopic march’. The epidemiology of atopic eczema is considered in Chapter 5, and the impact of the condition on children and their families/caregivers is considered in Sections 4.2 and 4.3.

Oral antifungal drugs for treating athlete's foot (tinea pedis)

Athlete's foot (tinea pedis) is a fungal infection of the feet that is easily spread and difficult to get rid of. This review compared different oral antifungal drugs (i.e. drugs taken by mouth), and it included 15 trials, involving 1438 participants. There are several different kinds of oral treatments, and the trials we found considered all the oral drugs used to treat athlete's foot. We found terbinafine and itraconazole to be more effective than placebo. And we found terbinafine to be more effective than griseofulvin. Griseofulvin is a treatment that was developed much earlier than the new treatments, such as terbinafine and itraconazole; these newer treatments tend to be most evaluated. Trials of other drugs were not large enough to show differences between them. All drugs had side‐effects; gastrointestinal effects were the most common.

Infection: Prevention and Control of Healthcare-Associated Infections in Primary and Community Care: Partial Update of NICE Clinical Guideline 2

Since the publication of the NICE clinical guideline on the prevention of healthcare-associated infections (HCAI) in primary and community care in 2003, many changes have occurred within the NHS that place the patient firmly at the centre of all activities. First, the NHS Constitution for England defines the rights and pledges that every patient can expect regarding their care. To support this, the Care Quality Commission (CQC), the independent regulator of all health and adult social care in England, ensures that health and social care is safe, and monitors how providers comply with established standards. In addition, the legal framework that underpins the guidance has changed since 2003.

See all (4)

Summaries for consumers

Nail fungus: Overview

Nail fungus is very common. Experts think that it often develops from untreated athlete's foot. It takes time to get rid of brittle, discolored, or thickened nails. Local treatment using nail polish can take up to a year. Tablets take effect more quickly, but have more side effects.

Nail fungus: Polish, cream or tablets?

Nail fungus can be very persistent. Topical treatment with nail polish may last as long as one year. Tablets for treating fungal nail infections usually have to be taken for several weeks or months. They are much more effective than topical treatments, but they have more side effects.Crumbly nails and a whitish-yellowish to brownish discoloration are typical signs of nail fungus. The nails may also become thicker and change shape. The affected part of the nail can become detached from the nail bed. Treatment options for nail fungus include nail polishes and creams as well as tablets. Nail polishes and creams are available in pharmacies without a prescription.

What are microbes?

Microbes are tiny forms of life that are found all around us. The most common kinds are bacteria, viruses and fungi.

See all (6)

More about Toenail Fungus

Photo of an adult

Also called: Toenail fungal infection

Other terms to know:
Fungal Infections, Fungus, Toenail

Keep up with systematic reviews on Toenail Fungus:

Create RSS

PubMed Health Blog...

read all...