What months are lice active?

Frequently Asked Questions About Head Lice Biting and Stinging Pests

Important Facts About Head Lice and Their Management

What are lice?

Are there different kinds of human lice?

Can head lice survive on pets?

How long do head lice live?

Can head lice hop or jump?

Do head lice spread diseases?

What are «nits»?

Where are nits found?

How many eggs does a female head louse lay?

How does someone get head lice?

How many head lice are usually found on an infested person?

Who is most likely to get head lice?

Is it true that African-Americans do not get head lice?

How can you tell if someone has head lice?

How can I check myself or my child for head lice?

What should be done if you suspect someone is infested?

Will soap and water kill lice?

What medications are effective against lice?

Do these medications kill the eggs?

How important is it to kill the eggs?

Do vinegar rinses help remove lice eggs?

Do I need to spray my home with an insecticide if someone in my family has head lice?

What else should be done in the classroom to get rid of lice?

Can lice be transferred between personal items like phones or headphones?

Does swimming help spread lice?

For information on the various lice that infest humans, see Insect Note Biology and Control of Human Lice.

Figure 1. Head louse.

Department of Entomology, University of Nebraska

Figure 1. Head louse.

Department of Entomology, University of Nebraska

Authors

Sydney Crawley Assistant Professor and Extension Specialist (Urban and Structural Pests)
Entomology and Plant Pathology

Patricia Alder Training Coordinator
Entomology and Plant Pathology

Find more information at the following NC State Extension websites:

Publication date: June 13, 1998
Revised: Oct. 24, 2022

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What Is Head Lice? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Head lice are tiny, wingless parasitic insects that reside on the scalp, where the temperature is warm, consistent, and very hospitable. Sometimes you can find head lice (Pediculus humanus capitis) on eyebrows, eyelashes, and neck hair as well. One place you will not find head lice? On dogs, cats, or any other animal. Head lice is a 100 percent human issue. And since head lice survive and thrive solely on human blood, once they’re separated from their human host, they starve and perish within several hours. Nits (head lice eggs), on the other hand, generally die within a week away from their human host. While it’s true that an infestation of head lice is inconvenient and perhaps uncomfortable, it’s usually harmless, notes the Centers for Disease Control and Prevention (CDC). (1)

Common Questions & Answers

How are head lice spread?

Head lice are only spread via direct head-to-head contact. They can’t jump or fly, but rather travel by crawling and — contrary to popular belief — cannot be spread by sharing items like hats, helmets, and hair brushes.

Can I go to school or work with head lice?

Even though the American Academy of Pediatrics insists that it’s okay to go to school or work with head lice, many schools still have “no-nit” policies that keep children from attending when affected with lice. Check with your work’s human resources department to see if they have policies regarding coming to work with lice.

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How do I treat head lice?

You should only treat head lice if you have a confirmed case: a live louse in the hair or on the scalp, or one or more nits (lice eggs) on the hair shaft within ¼ inch of the scalp. There are a number of prescription and nonprescription shampoos and creams available to treat lice, and nit combs are important for removing both lice and nits.

How do I get rid of head lice in my home for good?

Although lice can’t live for long without a human host, it’s important to treat your surroundings if someone in your home had lice. Wash and dry pillowcases, towels, pajamas, and other items the infected person used in hot water; soak brushes and hair items in hot water for 10 minutes; and vacuum. Sprays typically aren’t necessary and can be toxic.

What’s the difference between head, body, and pubic lice?

Head lice are small parasitic insects that feed on human blood and can be found on the scalp or in eyelashes, eyebrows, and neck hair. Pubic lice spread mostly via sexual contact and live in genital and anal areas. Body lice, the only lice known to spread disease, live on clothing and bedding but crawl onto skin multiple times daily to feed.

Signs and Symptoms of Head Lice

Not all people with head lice exhibit the very same lice symptoms. But the most common signs that you might be dealing with a head lice infestation include:

Itchiness This may be felt on the scalp, neck, or ears. Itching is often a sign of an allergic reaction to louse saliva or feces. (2) (Of note: For folks dealing with their first infestation, itching may not occur until two to six weeks after the outbreak begins.)

Trouble Sleeping Lice are more active in the dark, so those with an infestation may experience issues falling asleep thanks to this uptick in movement. (2)

Red Bumps or Sores For some, the infestation may go hand-in-hand with a rash, which can lead to excessive scratching. This can lead to a bacterial infection, complete with swollen lymph glands, tender skin, and oozing sores. If this occurs, your physician may treat the infection with an antibiotic. (3)

Visible Nits While the presence of nits does not always indicate that there’s an active infestation, it can. (2) Look for oval-shaped nits that are about the size of a grain of sand, stuck to the base of the hair shaft, closest to the scalp. At times, nits appear to be the same color as the hair in which they reside, making them very hard to spot. (Empty or hatched nits are lighter in color and further from the scalp and can be easier to see.) When not mimicking the host hair color, nits look yellow or whitish, which is why nits are often confused with dandruff or droplets of hair spray. (1)

Visible Nymphs or Lice Both nymphs (young lice) and mature head lice remain small — the size of a pinhead and the size of a sesame seed, respectively. They can be found on the scalp, around the ears, or at the base of the neck. They’ve got six legs and hook-like claws, and adults are often tan or grayish white. They may appear darker if their host has dark hair, though. (1) They may also appear red if filled with blood. (4)

Causes and Risk Factors of Head Lice

Contrary to popular belief, head lice cannot fly, jump, or hop, so it’s uncommon for people to spread lice by sharing belongings such as hats, helmets, and hair brushes. And personal hygiene — or lack thereof — has nothing to do with getting head lice. (1) Instead, “direct head-to-head contact is how we transfer lice,” says Richard J. Pollack, PhD, a senior environmental public health officer and researcher at the Harvard School of Public Health in Boston. (This was also confirmed by a study from 2015.) (5) With that, here are the risk factors of head lice:

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Young Age Children ages 3 to 11 get head lice most often. Because younger children tend to have more head-to-head interactions — sharing a bed, parent snuggles, wrestling — they have far more opportunity to spread their head lice with one another than older kids and adults. “As such, prevalence drops dramatically once kids get to middle school,” says Dr. Pollack. (The CDC lists attending day care and elementary school as a lice risk factor.) (1)

Proximity If you live with someone who’s dealing with a head lice outbreak, your chances of also becoming infested go up, regardless of age. (If one person is found to have head lice, all household members should be checked for head lice.) (1)

Sex Girls have a 2 to 4 times higher chance of becoming infested by lice than boys. It’s speculated that the reason may be attributed to the fact that girls often have longer hair, according to 2020 study. (6) It’s also thought that, perhaps, this may be because girls experience more frequent head-to-head contact than boys. (7)

Race Black children in the United States have far fewer reported head lice infestations than other ethnic groups, according to a report. (8) It’s thought that this may be due to differences in hair thickness and curl. And that fact that lice most frequently found in the United States have claws that may be better able to grasp the hair shafts of other races. (1)

How Is Head Lice Diagnosed?

The best way to zero in on an accurate diagnosis of head lice is to find a live nymph or adult louse on the scalp or hair. When looking, concentrate on the scalp, behind the ears, and around the nape of the neck. (3)

Lice are very small and move quickly, so begin by parting the hair into small sections and using a magnifying glass, as well as a special fine-toothed metal comb called a nit comb. The special lice comb may help you locate live lice more quickly and efficiently than without the comb, according to a study. (9)

“If you find a crawling bug on the scalp hair and it looks consistent with the images of head lice, then your lice conclusion is likely correct,” says Pollack. But if you are unable to find a live, moving louse, proceed with some doubt.

While most schools regularly screen children for lice, it’s important to know that this has not been proven effective at reducing the incidence of head lice in school. (3) “There are a lot of misdiagnoses at school head checks,” says Pollack. “Parents should carefully consider the evidence before starting treatment.” Again, finding a living and crawling bug on scalp hair that matches with the images of head lice is the best evidence.

“What parents and teachers sometimes believe to be nits are often confused with other things found in the hair, such as dandruff, hair spray residue, and dirt,” says Pollack. In fact, according to Pollock’s published research, most of the presumed “lice nits” and “lice” that doctors, nurses, and others have submitted to laboratories for identification were ultimately found not to be lice. (10) One common misdiagnosis is hair casts, or pseudonits — thin, elongated, firm, white attachments to the hair shaft that resemble nits. But unlike nits, they can easily be dislodged. (11)

That noted, nits are coated in a glue-like substance that very strongly attaches to the hair shaft, making it far more difficult to shake a nit loose than other foreign objects. If you discover lice eggs that are firmly attached within ¼ inch of the base of the hair shaft, you may be dealing with an infestation. If the lice eggs are found more than 1 centimeter from the scalp, on the other hand, they’re likely dead or already hatched, indicating an old and inactive infestation that doesn’t require further attention. (5)

If you discover a member of your household has lice, check everyone in the home who had close contact with the infested person every three or four days. (3)

Unsure whether or not you’re dealing with an active lice infestation? Visit a healthcare provider or a person specially trained to identify live head lice. That individual may use a specialized light called a Wood’s lamp, which makes the lice nits appear bluish in color. If suspicious lice eggs are found, they’ll be examined under a microscope to determine if there is, in fact, an active head lice infestation. (12)

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Head lice: Diagnosis and treatment

Watch this video for dermatologists’ tips to check for and treat lice.

Check for and treat head lice like a pro with these dermatologists’ tips.

Diagnosing head lice at home

If you are concerned that someone has head lice, you can usually diagnose this at home. You will need two common items:

Bright light
Fine-tooth comb or lice comb

What to do

You can find head lice by following these three steps:

Wet the hair of the affected child or adult, if possible. Some people think it’s easier to see the lice when the hair is wet. This also prevents the lice from scurrying away.
Sit the affected child or adult under a bright light.
Separate hair into sections. Beginning at the scalp, slowly comb outward through the hair section by section.

What to look for

You are looking for adult lice and their eggs (called nits). You’re more likely to see nits than adults because nits are firmly attached to the hair and do not move.

As you comb through the hair, look closely at the hair behind the ears and around the nape of the neck. These are likely places to find lice and nits.

Before the eggs hatch, you will see color, as shown here on the left. After the eggs hatch, you see a clear shell, as seen on the right.

If the person has adult lice or nits, you will see the following:

Adult lice: These look like one or more light-brown objects that resemble sesame seeds, often moving quickly. You can find these on the scalp or the hair.
Eggs: These are yellow, brown, or tan objects that look like tiny seeds and appear to be cemented to individual hairs close to the scalp. If an egg has hatched, the seed-like object will be clear.

When looking closely at the scalp and hair, it is important to know that kids—and adults—can have all kinds of stuff in their hair. You may see sand, dirt, lint, or dandruff. All of these comb out easily. Nits seem cemented to the hair and very difficult to remove.

Treating head lice at home

There are several products that you can buy at your local drug or grocery store to get rid of head lice and their nits. These are available without a prescription. Dermatologists offer the following tips for using these products:

First treatment

Carefully read and follow the directions. Using a lice shampoo usually involves lathering a shampoo into the hair and leaving the shampoo on for a few minutes before rinsing.
Apply the product to the head of a fully dressed person, and rinse the product out with a spray hose or running water from a sink. These products are not meant for use while taking a shower or bath. You want to limit the amount of skin that the product touches.
Use only one product. Using two products meant to treat head lice can be harmful. If two different products are necessary, your dermatologist can tell you which ones can be combined.
Use the amount stated on the product. Using more can be harmful.
Use the lice comb that comes with the shampoo. The teeth on a lice comb are closer together than the teeth on a regular comb. Placing the teeth closer together makes it easier to remove the lice and their nits.
Look at the hair 8 to 12 hours after treatment. If the lice seem as active as they were before the treatment, the medicine may not be working. Do not treat again. Talk with your dermatologist. A different lice medicine may be necessary.

The next day

If the medicine seems to be working, you’ll want to:

Wait two days to wash your hair. This lets the medicated product continue to work.
Continue to comb through the hair with the lice comb once a day. Doing this for two to three weeks helps to ensure that you get rid of the lice.

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Seven to nine days after the first treatment

Retreat as recommended on the package. Retreatment is generally recommended with all products you can buy without a prescription. Retreatment is usually done seven to nine days after the first treatment. The lice shampoos often are more successful at killing the adult lice than the nits, so retreatment helps to kill any surviving lice that hatched after the first treatment. No approved treatment for head lice can kill all the eggs during the first treatment.
After applying the second treatment, comb through the hair with the lice comb.
Wait two days to wash the hair.
Continue to comb through the hair with the lice comb once a day. Do this for two weeks, checking for lice and nits.

How to improve at-home treatment for head lice

Use a lice comb

Using a lice comb can improve the effectiveness of treatment. It also is important to use a lice comb when school policy requires that a child be “nit free” before returning to school.

If all this seems like too much trouble, another treatment option is to shave the scalp bald.

Treat family and friends

It is very common for close family and friends to get head lice. Dermatologists recommend that you check everyone for head lice. You do not want to treat anyone who does not have head lice; however, you should check everyone every day for 10 to 15 days.

When to see a dermatologist about head lice

If the at-home treatment does not work or this seems more than you can handle, you should see a dermatologist for treatment. Your dermatologist may recommend a product that you can buy without a prescription or a prescription medicine. The Food and Drug Administration (FDA) has approved the following prescription medicines to treat head lice:

Benzyl alcohol lotion: Approved to treat head lice in people 6 months of age and older, this medicine is applied to dry hair. When using this treatment, you want to saturate the scalp and hair. After 10 minutes, it’s time to thoroughly rinse off the medicine. Because benzyl alcohol kills the lice but not their eggs, it’s important to repeat the treatment in seven days.

When using this medicine, you’ll need to comb the hair for nits.

Women who are pregnant or breastfeeding can use this medicine to treat head lice. The most common side effect is irritated skin.

Ivermectin lotion: Approved to treat head lice in people 6 months of age and older, this medicine offers convenience. Invermectin treats most head lice with just one use and without the need to comb nits out of the hair.

Side effects include itchy skin, eye irritation (if the medicine gets in an eye), and a burning sensation on the skin. All are temporary.

Malathion lotion: Approved to treat people ages 6 years of age and older, malathion works by paralyzing and killing the lice and their eggs. This is very potent medicine, so be sure that you:

Keep the medicine away from everyone’s eyes. If the medicine gets in someone’s eyes, flush the eyes right away with lots of water for several minutes.
Do NOT smoke while using this medicine. If anyone in the room smokes while this medicine is being used, a fire can start. Leave cigarettes, cigars, and other things that you can smoke in another room.
Keep the medicine away from flames. You want to use malathion in a room without a stove or fireplace. Because malathion can easily cause a fire, even unlit lighters and camp stoves should NOT be in the room where you’ll use malathion. If you’re using malathion outdoors, be sure a camp fire is NOT burning.
Keep all electrical appliances that produce heat turned off. Using this medicine while a blow dryer, iron, curling iron, or space heater is running nearby can start a fire.

When used as directed, malathion is safe and effective. It can irritate the skin a bit as it works. Some people get dry hair or their skin can burn or sting. These side effects are temporary.

Spinosad suspension: This medicine is approved to treat head lice in people 6 months of age and older. It has been found to be safe and effective when used as directed.

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Like Ivermectin lotion:

Most people need to apply this medicine only once
Nit combing is not necessary

You will need to check the scalp seven days after treatment. If crawling lice are seen be sure to tell your dermatologist. You may need to repeat the treatment.

May be prescribed if other treatments fail or cannot be used

Lindane shampoo: This medicine has been approved by the FDA to treat head lice. Approved to treat head lice, this treatment is prescribed when other treatments do not work. It is essential to use lindane shampoo only as directed. It can be toxic when misused.

Treating your home for head lice

Whether you treat at home or see a dermatologist, you must also treat your home. To avoid another infestation, you should clean the following items:

Brushes and combs

Soak combs and brushes that a person with head lice used. Soak these in hot water, 130 degrees Fahrenheit or hotter, for 10 minutes.

Sheets, pillowcases, clothes, blankets, and towels

Place all items that touched the person’s head during the past two days in a washing machine and wash in hot water.
Dry all machine-washed items in a hot dryer, using the hottest setting. Dry for at least 10 minutes.

Stuffed animals and pillows

Place items that cannot be machine washed in a hot dryer and run the dryer on the hottest setting for 20 to 30 minutes.

Other personal items
Hair accessories, helmets, headphones, and other personal items can become infested with head lice. If a person with head lice has touched any of these items during the past two days, you can kill the lice on these objects by:

Sealing the objects in plastic bags
Placing the plastic bags in the freezer overnight or keeping the bags sealed for two weeks

Two weeks is the amount of time needed for adult lice and newly hatched lice to die when hot water, dryer heat, and freezing are impractical.

Furniture, carpets, and floors

Vacuum these thoroughly to pick up any hairs the person with head lice has shed. Everyone normally loses about 50 to 100 hairs a day.

When using prescription treatment for head lice, you still need to wash clothing, towels, and sheets that the person with head lice has used since getting head lice. Wash everything in hot water.

Outcome

Two treatments (spaced seven to nine days apart) often get rid of head lice. If your child or someone else in your family still has head lice after a few weeks, it means that the treatments did not work or the person got lice again. Make an appointment to see a dermatologist for help getting rid of the head lice. With proper treatment, it is possible to get rid of head lice.

Images
Images of head-lice eggs used with permission of Journal of the American Academy of Dermatology. (J Am Acad Dermatol 2006; 54(5):909-10)

Other images: Getty Images

References
Di Stefani A, Hoffman-Wellenhof R, Zalaudek I, et al. “Letters to the editor: Dermoscopy for diagnosis and treatment monitoring of pediculosis capitis.” J Am Acad Dermatol 2006; 54(5):909-10.

Early J and MacNaughton H. “Ivermectin Lotion (Sklice) for Head Lice.” Am Fam Physician. 2014 Jun 15;89(12):984-986.

Frankowski BL, Bocchini JA. “Head Lice.” Pediatrics 2010; 126(2):392-403.

Gunning K, Pippitt K, et al. “Pediculosis and Scabies: A Treatment Update.” Am Fam Physician. 2012 Sep 15;86(6):535-41.

Heymann, WR. “Head lice treatments: Searching for the path of least resistance.” J Am Acad Dermatol 2009; 61(2):323-4.

Jones KN, English JC, “Review of Common Therapeutic Options in the United States for the Treatment of Pediculosis Capitis.” CID 2003; 36(1):1355-61.

Ko CJ, Elston DM. “Pediculosis.” J Am Acad Dermatol 2004; 50(1):1-12

Miteva M, Tosti A. “Hair and scalp dermatoscopy.” In Press, J Am Acad Dermatol. 2012; 67(5):1040-8.

U.S. Food and Drug Administration, “Treating Head Lice.” FDA Consumer Health Information. July 2009.1-2.