“Head lice are very common and very treatable, especially when caught early,” says Victoria Catherine Weston, MD, an Emergency Medicine and Immediate Care physician at Northwestern Medicine.

What Are Head Lice?

Head lice are small, wingless insects that live on the human scalp and feed on blood. They survive by staying close to the skin, where they have access to warmth and a food source. Head lice are not a sign of poor hygiene and do not spread disease.

An adult louse (a single insect) is about the size of a sesame seed. Female lice lay tiny eggs, called nits, which attach firmly to the hair near the scalp. Head lice and nits are most often found behind the ears and at the neckline.

Lice live for about 28 days. Eggs hatch in about a week, and young lice mature into adults within two weeks. Once mature, a female louse can lay up to 10 eggs a day. If not treated, a head lice infestation can continue in repeating cycles every three weeks and become harder to manage.

What Do Head Lice Look Like?

Head lice are small but visible to the naked eye. Adult lice move quickly and may be difficult to see. Nits are even smaller and look like tiny yellow, white or tan dots stuck to the hair shaft. Unlike dandruff, lice eggs do not brush or shake off easily.

Seeing head lice and nits up close often requires bright light and a fine-toothed comb, also called a nit comb. Checking wet hair can make lice easier to see, since they move more slowly when wet.

What Causes Head Lice?

Head lice spread through person-to-person contact, most often through head-to-head contact. Lice cannot jump or fly, but they move quickly from one head to another when people are close together. This commonly happens during play, sports, school activities or sleepovers.

Head lice can also spread through close contact with personal items, such as hats, scarves, helmets, combs and brushes, although this is less common. Lice do not survive long away from the scalp, typically less than one or two days.

Avoiding head-to-head contact is the best way to reduce the risk, especially during an outbreak.

Who Is Likely To Get Head Lice?

Anyone can get head lice, but infestations are most common in children between ages 3 and 11. Children in day care and elementary schools may be at higher risk because of close contact during play.

Adults can get head lice too, especially parents, caregivers and family members who have close contact with children. Hair length, hair type and cleanliness do not affect the risk. Clean hair is just as likely to get lice as dirty hair.

“Getting head lice does not mean that you or your child is unclean,” says Dr. Weston. “It is easily transmitted and a very common issue.”

What Are the Signs and Symptoms of Head Lice?

A common symptom of head lice is itching of the scalp, which is caused by an allergic reaction to lice bites. However, itching may not start right away. It can take several weeks after exposure for symptoms to appear.

Other signs and symptoms of head lice include:

• A tickling feeling of something moving in the hair
• Small red bumps or sores on the scalp, neck or shoulders
• Trouble sleeping, since head lice are more active at night

Scratching can break the skin and increase the risk of infection, so treating lice early is important.

Checking for Lice

The best way to confirm a head lice infestation is to find a live louse or nymph (a young louse) on the scalp or hair. Nits alone may not always mean an active infestation, since empty eggshells can remain after treatment.

To check for lice:

• Use a fine-toothed nit comb on wet hair under bright light.
• Start close to the scalp and comb through small sections.
• Look carefully for crawling lice or nits firmly attached to the hair.

“It is a good idea to check early if you or your child have symptoms or if there is an outbreak at their school,” adds Dr. Weston.

Getting Rid of Head Lice

To treat head lice, it’s important to act fast and follow treatment steps carefully. For young children, talk with a doctor before starting treatment to be sure it’s appropriate and safe.

Many people start with over-the-counter or prescription shampoos and lotions to kill head lice. Always follow the product directions closely, including age recommendations, application instructions and guidance on when a repeat application may be needed.

Over-the-counter treatment options include:

• Permethrin lotion 
• Pyrethrin and piperonyl butoxide shampoo 
• Dimethicone

Prescription treatment options include:

• Benzyl alcohol lotion 
• Ivermectin lotion 
• Ivermectin tablets
• Spinosad topical suspension 

Some head lice have developed resistance to certain treatments, which means a second treatment or a prescription option may be necessary. If you’re unsure which treatment to use — or if over‑the‑counter products aren’t working — talk with your doctor for guidance.

After treatment, remove lice eggs by combing with a nit comb every few days for two weeks. This helps stop newly hatched lice from starting the infestation again.

Cleaning Your Home After Treatment

Cleaning your home can prevent head lice from coming back. Focus on items that had direct contact with the head:

• Wash recently worn clothing, bedding and hats in hot water and dry on high heat.
• Seal items that cannot be washed in a plastic bag for two weeks.
• Soak combs and brushes in hot water for at least 10 minutes.
• Vacuum floors, furniture and car seats.
• Dry clean clothing if needed.

Lice do not survive long away from the scalp, so deep or excessive cleaning is not necessary.

How Can You Prevent Head Lice?

No method guarantees prevention, but a few steps can help lower your risk:

• Avoid head-to-head contact when possible.
• Do not share hats, hair accessories, combs or brushes.
• Keep long hair tied back during school or activities.
• Teach children not to share personal items.

Checking for lice during outbreaks can help catch an infestation early and limit spread.

Head lice are common, especially among children, but they are manageable. Knowing the signs and symptoms can help you spot lice early. Understanding how lice spread and how to treat them can help you get rid of head lice — and keep them from coming back.

With prompt treatment and simple cleaning steps at home, most families can return to normal routines lice-free.