What Are Head Lice?

Head lice are tiny wingless insects. They live among human hairs and feed on blood from the scalp.

Head lice are a common problem, especially for little kids. But teens can get them too. They spread easily from person to person, and sometimes are tough to get rid of. Their bites can make the scalp itchy and irritated, and scratching can lead to infection.

Head lice are annoying, but they're not dangerous and they don't spread disease. They're not a sign of poor hygiene — head lice need blood and they don't care whether it's from someone who's clean or dirty.

It's best to treat head lice right away to prevent them from spreading.

What Are the Signs & Symptoms of Head Lice?

Lice are tiny, but you can still see them — though it's not always easy. An adult louse is grayish white or tan and about the size of a small sesame seed. Lice move fast, so you're actually more likely to see their eggs than the lice themselves.

Louse eggs are called nits. Nits look sort of like dandruff, except they don't brush or fall off as easily as dandruff. Lice attach their nits to pieces of hair, close to the scalp. If you think you have lice and see a small, oval blob on a strand of hair, it's probably a nit.

If nits are yellow, tan, or brown, it means the lice haven't hatched yet. If the nits are white or clear, the lice have hatched and just the egg remains. Lice eggs hatch within 1 to 2 weeks after they're laid.

Besides seeing nits or lice on the head, itching — or the feeling of something moving around on the scalp — is another clue that you might have lice. Like mosquito bites, the itching is a reaction to the saliva of the insect. Some people with lice also get a rash of small red bumps from scratching.

How Are Head Lice Treated?

The two main ways to treat lice are:

• medicine
• removing by hand

Medicine. If you think you have lice, call your doctor. Your doctor can recommend a medicated shampoo, cream rinse, or lotion to kill the lice. These may be over-the-counter (OTC) or prescription treatments. It all depends on what your doctor thinks will work best for you.

Lice can be hard to get rid of. If you still have lice 2 weeks after you started treatment, let your doctor know. Your doctor may want to try a different medication or repeat treatment in case any nits were left behind and hatched after treatment.

Lice are insects, so the treatments for lice are basically insecticides or pesticides. To avoid getting overexposed, you'll need to follow the directions carefully when it comes to how much to use and how often to use it. Medicated lice treatments usually kill the lice, but it may take a few days for the itching to stop.

Removing by hand. Your doctor may recommend wet combing in addition to (or as an alternative to) chemical treatments. Medicated treatments aren't 100% effective, so removing by hand is also important.

To remove lice and nits by hand, use a fine-tooth comb on wet, conditioned hair every 3–4 days for 3 weeks after the last live louse was seen. Go through small sections of hair at a time. Wetting the hair temporarily stops the lice from moving, and the conditioner makes it easier to get a comb through the hair. When possible, it works best to have someone else do the combing and removal.

You may have heard that petroleum jelly, mayonnaise, or olive oil can suffocate head lice, but these treatments may not be effective.

If you choose to get rid of lice without using medicine, you'll need to remove lice and nits carefully each week, for at least 3 weeks in a row. Watch for any live lice and take action if you see them.

Scratching a lot can lead to a scalp infection. Call your doctor as soon as possible if:

• the skin on your scalp is red and tender
• your scalp has crusting and oozing
• you have swollen lymph glands

Your doctor may want to treat an infection with antibiotics.

A few important things to NOT do: Don't use a hairdryer after applying scalp treatments. Some treatments for lice use flammable ingredients and can catch on fire. Don't use pesticide sprays or hire a pest control company to try to get rid of the lice; these can be harmful. Don't use essential oils (such as ylang ylang oil or tea tree oil) to treat lice on the scalp. They can cause allergic skin reactions and aren't approved by the U.S. Food and Drug Administration (FDA). Don't ever use highly flammable chemicals such as gasoline or kerosene.

How Can I Prevent Head Lice?

Lice can be tricky to get rid of because nits can remain unhatched on your head or you might pick up lice that are still on bedding or other items. Here's what to do if you've had lice — or someone in your family has:

• Wash bed linens and clothing that anyone with lice has used recently. Use very hot water (130°F [54.4°C]), then use the hot cycle of the dryer for at least 20 minutes.
• Take items that can't be washed to the dry cleaner. Or put them in airtight bags for 2 weeks.
• Vacuum carpets and any upholstered furniture, as well as car seats, then throw away the vacuum cleaner bag.
• Soak hair-care items like combs, barrettes, hair ties or bands, headbands, and brushes in hot water or just throw them away.
• Because lice can move easily from person to person in the same house, family members should be checked for lice. Anyone who has them needs treatment.

Here are some ways to avoid getting lice in the first place:

• Try to avoid head-to-head contact, like in gym or during sports.
• Don't share combs, brushes, hats, scarves, bandanas, ribbons, barrettes, hair ties or bands, towels, helmets, or other personal care items with anyone else.
• Don't lie on bedding, pillows, and carpets that someone with lice has used in the past couple of days.
• If someone in your family or at school has lice, ask a parent or adult to check your hair and scalp every 3–4 days to be sure you haven't picked up lice.