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Informed Health Online [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-.

Informed Health Online [Internet].

Head lice: Overview

Last Update: August 18, 2011; Next update: 2014.

Introduction

Head lice are tiny parasites that live in our hair and feed on blood from the scalp. Their bites can cause itching and they lay eggs called nits in the hair. Apart from this, though, they are not dangerous and do not cause any health issues. With the help of certain substances and strategies you can get rid of the small bloodsuckers. Without treatment, though, it is quite hard to get rid of them.

Causes

Head lice mainly affect children, and they spread quickly and easily from child to child. Head lice are especially likely to spread if people share brushes and combs.

Although some people think head lice are a sign of uncleanliness, being infected with head lice has nothing to do with poor hygiene. Head lice are very common. When researchers tested large groups of children to see how many have lice, they found that close to 10% do. It is not clear yet whether having long hair increases children’s risk of getting lice, but it makes it much harder to find them. There is no proof that lice prefer clean or dirty hair. They feed on blood, not dirt or skin cells on the scalp. One of the problems with having head lice is the unreasonable association with being dirty.

Diagnosis

The only way you can know for sure if a child has head lice is by finding a living louse. Although head lice often make your scalp itch, itching could also be caused by other things. Head lice are only 2 to 3 mm long. They have flat bodies and no wings. Unlike fleas, lice cannot jump. They are usually greyish brown in color, but this can vary. Because head lice are very small, it is difficult to see them in a tuft of hair. Carefully combing hair could help to find lice, particularly if it is damp – they might be detected this way.

If your child still has a few nits after being treated for head lice, but you have not found any lice for a while, they are probably gone. Dead or hatched nits can stick to the hair for a long time after the infestation with living parasites is over.

Treatment

Since head lice do not generally go away by themselves, treatment is necessary. Chemical treatments used to get rid of head lice are made from insecticides. However, they do not always work and many people avoid them because they contain insecticides. Silicone-based alternatives are now available that do not contain insecticides. Combing or using herbal products may not be enough to completely get rid of head lice.

Everyday life

Because head lice spread so easily, if your child has head lice you need to tell the people who are in close contact with your child. It is also important that children do not share their towels, bedding and combs with others as long as they have head lice. According to German law, children who have head lice must stay out of kindergarten or school until they are free of lice. What is more, parents are required to inform the establishment in question about their child’s head lice.

Sources

  • Burgess I. Head lice. Clinical Evidence 2009; 01: 1703.
  • Burgess IF, Brown CM, Lee PN. Treatment of head louse infestation with 4% dimeticone lotion: randomised controlled equivalence trial. BMJ 2005; 330: 1423. [PMC free article: PMC558378] [PubMed: 15951310]
  • Burgess IF, Lee PN, Matlock G. Randomised, controlled, assessor blind trial comparing 4% dimeticone lotion with 0.5% malathion liquid for head louse infestation. PLoS ONE 2007; 2: e1127. [PMC free article: PMC2043492] [PubMed: 17987114]
  • DTB. Does dimeticone clear head lice? Drugs Therap Bulletin 2007; 45: 52-55. [PubMed: 17718305]
  • Heukelbach J, Pilger D, Oliveira FA, Khakban A, Ariza L, Feldmeier H. A highly efficacious pediculicide based on dimeticone: randomized observer blinded comparative trial. BMC Infectious Diseases 2008; 8: 115. [PMC free article: PMC2553415] [PubMed: 18783606]
  • Infektionsschutzgesetz (IfSG). Infektionsschutzgesetz.
  • Jahnke C, Bauer E, Hengge UR, Feldmeier H. Accuracy of diagnosis of pediculosis capitis: visual inspection vs wet combing. Arch Dermatol 2009; 145: 309-313. [PubMed: 19289764]
  • Lebwohl M, Clark L, Levitt J. Therapy for head lice treatment based on life cycle, resistance, and safety considerations. Pediatrics 2007; 119: 965-973. [PubMed: 17473098]
  • London New Drugs Group. Hedrin and Lyclear Spray Away for the treatment of head lice. APC/DTC Briefing. London: London New Drugs Group. October 2007.
  • Roberts RJ, Burgess IF. New head-lice treatment: hope or hype? Lancet 2005; 365: 8-10. [PubMed: 15639662]
  • Robert Koch-Institut (RKI). Kopflausbefall (Pediculosis capitis). RKI-Ratgeber Infektionskrankheiten - Merkblätter für Ärzte. Berlin: Robert Koch-Institut. 2007.
  • IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

    Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

    Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

© IQWiG (Institute for Quality and Efficiency in Health Care)

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