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Health Information | 10/12/2021

Head Lice: How to Identify, Treat, and Prevent Further Spread

By  Michael Flynn, MD
As children have returned to in-person learning and sports, cases of head lice become even more common. Head lice are tiny parasitic insects that feed on human blood and cling to the scalp and neck. Each louse is only about the size of a sesame seed and is tan, grey, or brown. Lice lay light, pale eggs (nits) on hairs near the scalp that are held together with a glue-like substance.

Although lice cannot fly, they can easily be spread through close contact or sharing items like hairbrushes, helmets, car seats, bedding, or hats. Although head lice is a frustrating and uncomfortable condition, it is extremely common. According to the CDC, an estimated 6 to 12 million infestations occur each year in the United States among children 3 to 11 years of age.

Identifying Head Lice

The most common symptom of head lice is itchiness on the scalp and neck. In addition, scratching commonly causes small sores in these areas.

The best way to determine if your child has lice is to check his or her head. Lice typically stay close to the scalp and behind the ears and can appear in the following different forms:

Nits or lice eggs: Female adult lice typically lay 6 to 8 eggs each day on the scalp. These eggs (nits) are about half the size of a pinhead and typically camouflage with the person’s hair color, making them hard to see. Nits are often confused with dandruff or product buildup; however, they are laid on the first 1 to 2 inches of the hair shaft closest to the scalp and are hard to remove. Head lice nits usually hatch in 8 to 9 days, leaving behind clear shells that remain stuck to the hair and usually appear white or gray in color.

Nymph: A baby louse is called a nymph and is what hatches from the nit. Nymphs feed on the blood from the scalp and grow for 9 to 12 days before becoming adult lice. They move quickly and can be seen on your hair, skin, and anything your head touches. Itching is a delayed reaction to their feeding and can take 4 to 6 weeks to develop after first exposure. Subsequent exposures can cause itching in 1 to 2 days. The itching is often worse at night.

Adult lice: An adult louse is about 2 to 3 millimeters long and has 6 legs with claws at the end that allow them to latch tightly to hair. Adult lice can typically live for 30 days on the head but die within 1 to 2 days if they fall off.


It is extremely important to treat head lice quickly after diagnosis and notify any friends, family members, or classmates that could have been exposed. Experts recommend treating your child if you see lice on his or her head or if he or she shares a bed with someone who has lice. Children also should be checked for lice if they live or have had close contact with someone who has lice, but treatment is not necessary if there is no sign of a live case. Ideally, items that have been in contact with the head of an infected individual should be cleaned within 48 hours.

There are several different head lice treatments that are safe and effective for children, including the following:

Medications: Medications that treat lice are called pediculicides. Some pediculicides only kill live lice, and others kill nits as well. Pediculicides that only kill lice should be repeated to ensure that recently born nymphs are killed. These medications are available over the counter or with a prescription and include shampoos, lotions, and cream rinses.

Home remedies: Some people prefer to treat lice using chemical-free home remedies. One common practice is wet combing, where you run a fine-tooth comb through wet hair at least once a week to remove active lice and their eggs. Another common treatment is soaking the scalp and hair in olive oil, petroleum jelly, mayonnaise, or another greasy substance to suffocate live lice. Essential oils such as tea tree and anise may also suffocate and kill lice. These treatments can be paired with pediculicides for maximum effectiveness.

After treating your child for head lice, it is equally important to remove the remaining lice in your home. Lice can crawl on soft surfaces like bedding, couches, pillows, and hats but need human blood to survive longer than 1 to 2 days. There are the following ways to ensure that the hard work of treatment is not wasted by getting rid of all remaining lice around the house:

Heat: Lice and nits die when exposed to temperatures higher than 130 degrees F for more than 5 minutes, so wash all clothing items and communal pillows, blankets, and rugs in hot water before drying on high heat.

Bag items: For items that cannot be washed or dried, put them in a plastic bag and store them away from people for 2 weeks to ensure all remaining lice and nits on them have died.

Vacuum: Vacuum all rugs, couches, other soft furniture, and floors to remove hairs that may have active lice eggs attached.

Clean hair tools: Soak all brushes, combs, and other hair accessories in the house in hot, soapy water for 5 to 10 minutes.

Prevention of Head Lice

It is best to have a conversation with your child about close head-to-head contact to prevent future cases of head lice. Avoiding close contact and small shared spaces can reduce the spread of lice in schools and camps and among sports teams. Also, your child should not share personal belongings such as hats, helmets, and hairbrushes with his or her peers to reduce the likelihood of catching lice.

Contact your Atrius Health provider if you suspect that your child has lice to learn more about treatment and prevention options.

About The Author

Michael Flynn, MD

Dr. Michael Flynn joined Atrius Health in 2021 and is a board-certified family medicine provider at our PMG Bourne location. He received his medical degree and completed his residency at the University of Massachusetts Medical School in Worcester. Dr. Flynn’s clinical interests include team-based care of patients of all ages, women’s and reproductive health, behavioral health, evidence-based medicine, and practice and medical record efficiency.

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