Health Library

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 kids. They spread easily from person to person, and sometimes are tough to get rid of. Their bites can make a child’s 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?

Even though they’re tiny, you can see head lice. Here’s what to look for:

• Lice eggs (nits). These look like tiny yellow, tan, or brown dots before they hatch. Lice lay nits on hair shafts close to the scalp, where the temperature is perfect for keeping warm until they hatch. Nits look a bit like dandruff, but aren’t removed by brushing or shaking them off.

  Unless a child has many head lice, it’s more common to see nits in the hair than live lice crawling on the scalp. Lice eggs hatch 1–2 weeks after they’re laid. After hatching, the remaining shell looks white or clear and stays attached to the hair shaft. This is when it’s easiest to spot them, as the hair is growing longer and the egg shell is moving away from the scalp.

• Adult lice and nymphs (baby lice). Adult lice are no bigger than a sesame seed and are grayish-white or tan. Nymphs are smaller and become adult lice about 1–2 weeks after they hatch. This life cycle repeats itself about every 3 weeks. Most lice feed on blood several times a day, and they can survive up to 2 days off the scalp.
• Scratching. With lice bites come itching and scratching. This is due to a reaction to the saliva (spit) of lice. But the itching doesn’t always start right away. It depends on how sensitive a child’s skin is to the lice. It might take weeks for kids with lice to start scratching. They may complain, though, of things tickling or moving around on their heads.
• Small red bumps or sores from scratching. Some kids have mild irritation from scratching, while others may get a bothersome rash. Scratching a lot can lead to a bacterial infection. Watch for swollen lymph nodes (glands) on the back or front of the neck, and red, tender skin that might have crusting and oozing. Doctors can treat a skin infection with an antibiotic.

How Can I Check My Child for Head Lice?

Look for lice and nits on the scalp, behind the ears, and around the nape of the neck. It’s rare for lice to be in eyelashes or eyebrows.

It can be tough to find a nymph or adult louse. Usually, there aren’t many of them and they move fast. Look for nits attached to the hair near the scalp. They can look like dandruff or dirt. To tell them apart, pull on the little speck with your fingers — dandruff and dirt can be removed, but nits stay stuck. A magnifying glass and a bright light can help with your inspection.

The best way to check is by using a fine-tooth comb on wet hair. After applying lots of conditioner, comb the hair out in very small sections, and look for lice or nits on the comb. You can wipe the comb onto a tissue or paper towel where it will be easier to see them. 

If your child is itchy and scratching their head but you’re not sure if it’s lice, ask your child’s doctor or the nurse at school or childcare center to take a look.

How Are Head Lice Treated?

The two main ways to treat lice are:

• medicine
• removing by hand

Medicine: Medicated shampoos, cream rinses, and lotions are available that kill lice. These may be over-the-counter (OTC) or prescription medicines. If you buy OTC, be sure it’s safe for your child’s age. While some over-the-counter shampoos are safe for kids as young as 2 months, others are safe only for kids 2 years and older.

In some areas, lice have developed resistance to some medicines. This means they no longer work to kill the lice. Ask your doctor or a pharmacist to recommend a medicine known to work in your area. The doctor also can prescribe a medicated shampoo or lotion. For very resistant lice, the doctor might recommend taking medicine by mouth.

Whether the medicine is OTC or prescription, always follow the directions closely. Applying too much can be harmful. Applying too little won’t work.

Removing by hand: Removing lice and nits by hand can finish the job if the medicine did not completely rid your child of lice (no medicine is 100% effective). It is also an option for anyone who doesn’t want to use an insecticide. And it is the only option for children 2 months old or younger, who should not use medicated lice treatment. 

To do this, use a fine-tooth comb on wet, conditioned hair every 3–4 days for 3 weeks after the last live louse was seen. Wetting the hair temporarily stops the lice from moving, and the conditioner makes it easier to get a comb through the hair.

There’s no need to buy electronic combs that claim to kill lice or make nits easier to remove. No studies have been done to back up these claims. You also don’t need to buy special vinegar solutions to apply to the scalp before picking nits. Water and conditioner works fine.

Though petroleum jelly, mayonnaise, or olive oil are sometimes used to try to suffocate head lice, these treatments may not work. If medicine doesn’t work and you want to try these methods, talk to your doctor first.

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 on anyone.

Are Head Lice Contagious?

Head lice spread quickly from person to person, especially in group settings like schools, childcare centers, slumber parties, sports activities, and camps.

They can’t fly or jump, but they have claws that let them crawl and cling to hair. They spread through head-to-head contact, and sharing clothing, bed linens, combs, brushes, and hats.

Pets can’t catch head lice and pass them on to people or the other way around.

Do Kids Have to Stay Home From School?

In the past, kids with head lice were kept home from school. But now doctors don’t recommend these “no-nit” policies. In most cases, a child who has lice should stay at school until the end of the day, go home and get treatment, and return to school the next day. While they are at school, kids should avoid head-to-head contact with other kids. It can help to put long hair up in a bun, braid, or ponytail.

Can We Prevent Head Lice?

To get rid of head lice and their eggs, and to help prevent them from coming back:

• Wash all bed linens, stuffed animals, and clothing used during the 2 days before treatment (any lice that fell off before that will not be alive). Wash in very hot water (130°F [54.4°C]), then put them in the hot cycle of the dryer for at least 20 minutes.
• Dry clean items that can’t be washed. Or put them in airtight bags for 2 weeks.
• Vacuum carpets and any upholstered furniture (in your home or car), and throw away the vacuum cleaner bag.
• Soak hair-care items like combs, barrettes, hair ties or bands, headbands, and brushes in hot water or throw them away. Tell kids not to share these items.
• Because lice easily pass from person to person in the same house, check all family members. Treat everyone who has lice so they won’t pass it back and forth.
• Tell kids to try to avoid head-to-head contact at school (in gym, on the playground, or during sports) and while playing at home with other children.
• Every 3 or 4 days, check kids who had close contact with a person who has lice. Then, treat any who have lice or nits close to the scalp.

Will They Ever Be Gone?

As many parents know, fighting head lice can be an ongoing battle. There’s no doubt that they can be hard bugs to get rid of.

If you’ve tried everything and your child still has lice, it could be because:

• some nits were left behind (if you see nits far from the scalp — more than ½ inch (1 cm) — and no live lice, these are probably dead and treatment likely isn’t needed)
• your child is still around someone who has lice
• the treatment you’re using isn’t effective

If your child has lice 2 weeks after you started treatment or if your child’s scalp looks infected, call your doctor.

There are professional lice treatment centers that remove lice and nits for a fee. These services are effective but often costly.

Looking Ahead

Remind your child that while having lice can be embarrassing, anyone can get them. Having head lice is not a sign of dirtiness or poor hygiene. The pesky little bugs can be a problem no matter how often kids do — or don’t — wash their hair or bathe.

Dealing with head lice can be frustrating, but be patient. Follow the treatments and prevention tips from your doctor, and soon your family will be lice-free.