Head lice
Pediculosis capitis - head lice; Cooties - head lice
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.
Head lice infect the scalp and hair and can be seen at the nape of the neck and over the ears. Head lice spread easily and quickly but do not carry disease as other lice do.
This photograph shows a nit, or tiny white egg sack, attached to the shaft of a human hair. Image courtesy of D. Scott Smith, MD, MSc, DTMH.
This is a photograph of a head louse emerging from an egg. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.
This is a photograph of a male Pediculus humanus var. capitis, a head louse. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.
This is a photograph of a female Pediculus humanus var. capitis, a head louse. Head lice have become an increasing problem in schools and day care centers. Some grade schools have started programs to examine children for head lice.
This is a close-up picture of lice egg sacks (nits) on the hair. They cling to individual hair shafts. (Image courtesy of the Centers for Disease Control and Prevention.)
This photograph shows the nits or tiny white egg sacks attached to the hairs. Schools often insist that these be entirely removed before a child returns to school.
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:
- You come in close contact with a person who has lice.
- You touch the clothing or bedding of someone who has lice.
- You share hats, towels, brushes, or combs of someone who has lice.
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.
If a child is scratching their head a lot, there's a chance the child has head lice. Head lice are tiny insects that sort of look like a grain of rice with six legs. They infect the hair on your head, laying tiny eggs that look like dandruff. Because they can live up to 30 days on a human, head lice spread easily, especially among children at school and daycare centers. You can get them in close contact with others who have head lice or by sharing hats, towels, brushes, or combs of someone with head lice. Head lice cause intense itching on your child's scalp. Your child may have small, red bumps on their scalp, neck, and even their shoulders. You may notice tiny white specks, they're head lice eggs, on the bottom of hair, close to your child's scalp. You'll need to look closely at your child's hair to see head lice. Look at their head under a bright light with a magnifying glass, and make sure you wear disposable gloves. Part your child's head down to the scalp in very small sections. You'll be able to see moving lice and eggs. The eggs will be very hard to remove because they're attached to the hair with a substance that's like glue. Among the most common solutions are lotions and shampoos that contain a chemical called permethrin, or Nix. You can find them at a drug store. You can also use several natural remedies. If these don't work, your child's doctor can give you something stronger. You may need to treat others who've shared a bed or clothing with the child who has lice. After treating your child's head, you'll want to remove all of the eggs. Some dishwashing liquids can help dissolve that glue that makes the eggs stick to hair, or you can rub olive oil in the hair. A fine metal comb is best for removing the eggs, and running the comb's teeth through beeswax first will help. This is called nit combing. You'll want to comb the child's hair for eggs again in about 7 to 10 days. Some people treat lice with careful nit combing alone, perhaps combined with heat. Lice can survive up to 55 hours without contact with a human host, so it's also important to wash all of the child's clothing and bedding in hot water with detergent, unless you can ensure no contact for more than 55 hours. This helps prevent the lice from spreading to others. Treating lice usually kills them, but they may come back, especially if the infection is running through your child's classroom or daycare. That's why when one case is detected in a family, school, or daycare center, it makes sense for every child at the location to be examined for head lice.
Symptoms
Symptoms of head lice include:
- Very bad itching of the scalp
- Small, red bumps on the scalp, neck, and shoulders (bumps may become crusty and ooze)
- Tiny white specks (eggs, or nits) on the bottom of each hair that are hard to get off
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:
- Part the hair all the way down to the scalp in very small sections.
- Examine the scalp and hair for moving lice and eggs (nits).
- Look at the whole head in the same way.
- Look closely around the top of the neck and ears (the most common locations for eggs).
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:
- Rinse and dry the hair.
- Apply the medicine to the hair and scalp.
- Wait 10 minutes, then rinse it off.
- Check for lice and nits again in 8 to 12 hours.
- If you find active lice, talk to your provider before doing another treatment.
You also need to get rid of the lice eggs (nits) to keep lice from coming back.
To get rid of nits:
- You can use products that make the nits easier to remove. Some dishwashing detergents can help dissolve the "glue" that makes the nits stick to the hair shaft.
- Remove the eggs with a nit comb. Before doing this, rub olive oil in the hair or run the metal comb through beeswax. This helps make the nits easier to remove.
- Metal combs with very fine teeth are stronger and work better than plastic nit combs. These metal combs are easier to find in pet stores or on the Internet.
- Comb for nits again in 7 to 10 days.
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:
- You still have symptoms after home treatment.
- You develop areas of red, tender skin, which could signal an infection.
Prevention
Some of the steps to prevent head lice are:
- Never share hair brushes, combs, hair pieces, hats, bedding, towels, or clothing with someone who has head lice.
- If your child has lice, be sure to check policies at schools and daycare. Many places do not allow infected children to be at school until the lice have been completely treated.
- Some schools may have policies to make sure the environment is clear of lice. Cleaning of carpets and other surfaces often helps prevent spread of all types of infections, including head lice.
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.
Version Info
Last reviewed on: 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.
