Head lice

Definition

Head lice are tiny insects that live on the skin covering the top of your head (scalp). Head lice may also be found in eyebrows and eyelashes.

Lice spread by close contact with other people.

Alternative Names

Pediculosis capitis - head lice; Cooties - head lice

Causes

Head lice infect hair on the head. Tiny eggs on the hair look like flakes of dandruff. However, instead of flaking off the scalp, they stay in place.

Head lice can live up to 30 days on a human. Their eggs can live for more than 2 weeks.

Head lice spread easily, particularly among school children ages 3 to 11 years. Head lice are more common in close, overcrowded living conditions.

You can get head lice if:

Having head lice causes intense itching but does not lead to serious medical problems. Unlike body lice, head lice never carry or spread diseases.

Having head lice does not mean the person has poor hygiene or low social status.

Symptoms

Symptoms of head lice include:

Exams and Tests

Head lice can be hard to see. You need to look closely. Use disposable gloves and look at the person's head under a bright light. Full sun or the brightest lights in your home during daylight hours work well. A magnifying glass can help.

To look for head lice:

Both children and adults should be treated right away if any lice or eggs are found.

Treatment

Lotions and shampoos containing 1% permethrin (Nix) often work well. You can buy these medicines at the store without a prescription. If these products do not work, a health care provider can give you a prescription for stronger medicine. Always use the medicines exactly as directed. Using them too often or in the wrong way can cause side effects.

To use the medicine shampoo:

You also need to get rid of the lice eggs (nits) to keep lice from coming back.

To get rid of nits:

When treating lice, wash all clothes and bed linens in hot water with detergent. This also helps prevent head lice from spreading to others during the short period when head lice can survive off the human body.

Ask your provider if people who share bedding or clothes with the person who has head lice need to be treated as well.

Outlook (Prognosis)

Most of the time, lice are killed with the proper treatment. However, lice can come back if you do not get rid of them at the source.

Possible Complications

Some people will develop a skin infection from scratching. Antihistamines can help ease itching.

When to Contact a Medical Professional

Call your provider if:

Prevention

Some of the steps to prevent head lice are:

References

Burkhart CN, Burkhart GG, Morrell DS. Infestations. In: Bolognia JL, Schaffer JV, Cerroni L, eds. Dermatology. 4th ed. Philadelphia, PA: Elsevier; 2018:chap 84.

James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM. Parasitic infestations, stings, and bites. In: James WD, Elston DM, Treat JR, Rosenbach MA, Neuhaus IM, eds. Andrew's Diseases of the Skin Clinical Dermatology. 13th ed. Philadelphia, PA: Elsevier; 2020:chap 20.

Seifert SA, Dart R, White J. Envenomation, bites, and stings. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 104.


Review Date: 2/24/2022
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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