Head Lice: What They Are, How They Spread, and How to Get Rid of Them for Good
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Head lice are tiny insects that feed on blood from the scalp and are found worldwide. They are not a sign of poor hygiene and do not spread diseases. They spread mainly through direct head-to-head contact, most often among preschool and school-age children. Itching is the most common symptom, but it can take four to six weeks to appear [1]. Diagnosis is based on finding live lice or live nits near the scalp, and treatment uses OTC or prescription medicines — often with a second treatment nine to ten days later to catch newly hatched lice [2].
Quick Answer: What is head lice and how do you get rid of it?
Head lice are small insects, about the size of a sesame seed, that live in human hair and feed on blood from the scalp. They spread mostly through head-to-head contact and are very common in young children. Treatment uses medicines applied to the hair, often repeated 9 to 10 days later, plus combing with a nit comb.
What the research says
A single ivermectin application cleared most infestations in two large trials. In two randomized, double-blind studies with 765 patients aged 6 months or older, one 10-minute application of 0.5% ivermectin lotion left 94.9% of patients louse-free on day 2, compared with 31.3% for the vehicle lotion, and 73.8% versus 17.6% on day 15, without nit combing (Pariser et al., N Engl J Med, 2012 [3]).
Resistance to permethrin and pyrethrin products is common worldwide. A systematic review and meta-analysis of 24 studies estimated the mean frequency of pyrethroid resistance in head lice at 76.9%, and four countries (Australia, England, Israel, and Turkey) reported 100% kdr gene frequencies. This may help explain why some over-the-counter treatments fail (Mohammadi et al., Parasite, 2021 [4]).
Oral ivermectin is an option when lotions fail. In a randomized trial of 80 children with head lice, a single oral dose of ivermectin (200 µg/kg) cured 77.5% of children, compared with 87.5% for 0.5% malathion lotion. After a second dose for those who did not respond, cure rates rose to 92.5% and 95%, respectively (Nofal, J Dtsch Dermatol Ges, 2010 [5]).
What Is Head Lice?
Head lice are tiny insects that feed on human blood, most often from the scalp. These insects are found worldwide, and they infect hair of any length and any type.
In the United States, head lice tends to affect young children and the caregivers who look after them. The insects mainly spread by crawling directly from the hair of one person to the hair of another.
A key fact that surprises many parents: having head lice is not a sign of being unclean or living in an unclean place. Head lice do not spread diseases.
Symptoms: What to Look For
Itching is the most common symptom of head lice. However, people who have head lice for the first time may not feel itchy right away. It can take 4 to 6 weeks for itching to start after the first infestation.
You may be able to see lice, but they move quickly, avoid light, and are small. You may also see lice eggs on hair shafts. Also called nits, lice eggs stick to the shaft of the hair and are easiest to see around the ears and the hairline of the back of the neck. Because they are tiny, it may be easier to spot empty nits, especially on darker hair. Empty nits are lighter in color and sit further from the scalp.
An important point: seeing empty nits does not mean there are live lice. That is especially true if the nits are greater than 1/4 to 3/8 inches (6 to 9.5 millimeters) from the scalp.
Sores on the scalp, neck, and shoulders are another symptom. Scratching can lead to small bumps that appear red on white skin and may be harder to see on Black or brown skin. These sores may get infected.
Symptom | What It Looks Like | Key Details |
Itching | Persistent scalp itch | Most common symptom; first-time infestations may take 4 to 6 weeks to start itching |
Visible lice | Small, tan or gray insects | Move quickly, avoid light, about the size of a sesame seed |
Nits (eggs) | Tiny eggs stuck to hair shafts | Easiest to see around ears and back of neck; empty nits are lighter and further from scalp |
Empty nits | Light-colored, distant from scalp | May not mean live lice, especially if more than 1/4 to 3/8 inch from scalp |
Sores | Small bumps from scratching | May get infected; appear red on white skin, harder to see on Black or brown skin |
Causes: How Head Lice Spread
Head lice infestation is most often caused by direct contact with these insects. A louse is a tan or gray insect about the size of a sesame seed. The female louse sticks each egg to the base of a hair shaft less than 1/8 inch (3 millimeters) from the scalp.
The Louse Life Cycle
A louse goes through three stages:
Eggs (nits) — hatch after 7 to 12 days.
Nymphs — immature forms that become mature adults after about seven days; nymphs also feed on blood from the scalp.
Adult lice — can live for 3 to 4 weeks; the female lays up to 10 eggs a day.
Transmission: How Lice Move From Person to Person
Head lice crawl, but they cannot jump or fly. They most often spread from one person to another through head-to-head contact. This frequently happens within families or among children who have close contact with each other.
It is less common for head lice to spread without direct contact. But lice may spread through shared items if one person is infected, including:
Clothing, such as hats, scarves, and sports uniforms
Brushes and combs
Items worn in the hair, such as headphones, hair clips, headbands, and ribbons
Pillows, towels, stuffed animals, and furniture fabric
Household pets, such as dogs and cats, do not spread head lice.
Risk Factors
Head lice infect hair of any length and any type. Because they spread mainly by direct head-to-head contact, the risk of spreading head lice is greatest among children who play or go to school together. In the United States, head lice most often occurs in children in preschool through grade school.
Risk Factor | Why It Matters |
Young age (preschool to grade school) | Children have the most head-to-head contact during play and school |
Caregivers of affected children | Close physical contact with infested children raises risk |
Shared hair items | Brushes, combs, hats, scarves, and hair accessories can carry lice |
Shared bedding and furniture | Pillows, towels, and fabric upholstery may harbor lice briefly |
Complications
When people scratch the itch that head lice cause, the skin may break. The broken skin may then get infected. This is the most common complication of head lice.
When to See a Doctor
Most people who have head lice do not need to contact a healthcare professional. But if you think you or your child has lice, a member of your healthcare team can confirm the presence of head lice and suggest the best treatment.
If you are not sure whether you or your child has head lice, see a healthcare professional. It is easy to mistake other things for nits, including:
Dandruff
Hair products, such as hair spray droplets
Beads of dead hair tissue on a hair shaft
Scabs, dirt, or hair changes from a fungal infection
Other small insects that might be in the hair
How Head Lice Is Diagnosed
To diagnose a head lice infestation, you or a healthcare professional look for lice at any stage of the life cycle. Young lice or adults may be seen or collected with a comb. The fine-toothed comb, called a nit comb, is used from the scalp to the end of the hair. Guidelines suggest looking at wet hair that has been coated with hair conditioner or other products.
Identifying Nits
Check for nits at the hairline, especially behind the ears. A live nit needs to be near the scalp to survive. Nits found more than about 1/4 inch (6 millimeters) from the scalp are likely dead or empty. Use a magnifying lens to confirm that what you are looking at is head lice eggs. Or see a healthcare professional who can help identify nits.
Diagnostic Step | What It Involves |
Visual inspection | Look for lice at any life stage on the scalp and hair |
Nit combing | Fine-toothed comb used from scalp to hair ends on wet, conditioned hair |
Nit identification | Check hairline and behind ears; live nits must be near scalp |
Magnification | Use a magnifying lens or see a healthcare professional to confirm |
Treatment Options
To kill head lice and lice eggs, you can use a few methods. Wet combing, smothering, or dehydrating are ways to kill head lice. Or you can use medicine available with or without a prescription.
The medicine may not kill the newest eggs. So a second treatment at the right time to kill nymphs may be needed. Depending on the medicine you use, most often you treat again 7 to 10 days after the first treatment. Ask a member of your healthcare team to write down the treatment schedule.
Treatment Type | Medicine or Method | Age Range | Key Instructions |
OTC lotion | Permethrin or pyrethrin products | 2 months and older | Apply per package directions; comb out nits; repeat in 9 to 10 days; keep combing every 2 to 3 days for 2 to 3 weeks |
OTC lotion | Ivermectin (topical) | 6 months and older | Apply once to dry hair; rinse after 10 minutes; don't repeat without healthcare guidance |
Prescription lotion | Spinosad | 6 months and older | Apply to dry hair for 10 minutes; rinse; don't shampoo 24–48 hours; repeat in 7 days if lice seen |
Prescription lotion | Malathion | 6 years and older | Apply for 8 to 12 hours; rinse; don't shampoo 24–48 hours; repeat in 7 days; flammable — no heat styling or open flame |
Prescription oral | Ivermectin (oral) | Children over 33 lb (15 kg) | For cases where topical treatments fail; repeat in 7 to 10 days if needed |
Non-medicine | Wet combing | Any age | Fine-toothed nit comb on wet, conditioned hair; can replace or follow medicine |
Non-medicine | Hot air dehydration | Any age | Machine-based treatment at professional lice centers; don't use a hair dryer |
Over-the-Counter Medicines
Follow all product label directions and do not use more than the label or your healthcare professional says to use. Do not use more than one head lice treatment medicine at a time. The side effects of all the products applied to the scalp may include itching and mild burning of the scalp that can last for days.
Permethrin or products containing pyrethrin are used for people age 2 months or older. After applying, remove nits with the comb included in the package. Repeat the treatment 9 to 10 days later. Keep combing out the nits every 2 to 3 days for 2 to 3 weeks until no nits remain on the scalp.
Ivermectin lotion can be used by adults and children age 6 months or older. Apply it once to dry hair and rinse with water after 10 minutes. Do not use it again without talking with a healthcare professional.
Prescription Medicines
In some parts of the world, medicines available without a prescription no longer kill lice. Also, these medicines can fail if you do not use them correctly or repeat them as instructed. If the correct use of an over-the-counter treatment has failed, your healthcare professional may suggest prescription treatments.
Spinosad is for adults and children age 6 months and older. Apply it to dry hair and leave it on for 10 minutes. Rinse with warm water over a sink to keep the lotion from getting on the skin. Do not shampoo hair for 24 to 48 hours. Repeat in seven days if you see lice.
Malathion is for adults and children age 6 years and older. Put the lotion on the hair and leave it on for 8 to 12 hours. Then rinse it out using warm water over a sink. Do not shampoo hair for 24 to 48 hours. Repeat in seven days if you see lice. This medicine is flammable, which means it can cause fires. Do not use it with a hair dryer or curling iron or near an open flame.
Oral ivermectin is a prescription you take by mouth. It can be given to children who weigh more than 33 pounds (15 kilograms) if topical treatments do not rid the scalp of head lice. It can be repeated in 7 to 10 days if needed.
Wet Combing
Combing wet hair with a fine-toothed nit comb may remove lice and some nits. You can do this after treatment of the scalp with a medicine or in place of a medicine. Start by wetting the hair or coating it with hair conditioner or other products that can slow lice. Some options are products with dimethicone, mayonnaise, or petroleum jelly.
Do not use household products that are not meant for humans, anything that could catch fire easily, or chemicals that can irritate the skin.
Smothering Agents
Some people use household products to keep head lice from getting air. These include mayonnaise, margarine or butter, or petroleum jelly. People put a large amount of the product on the hair, cover the head with a shower cap, and leave it on overnight. It is not clear how well these products work.
Dehydration
Another treatment is a machine that uses hot air to kill head lice and their eggs by drying them out. This process is called dehydration or desiccation. People who operate the machines need special training, and professional lice treatment centers may offer them.
Do not try to use a hair dryer to get rid of lice. A hair dryer can send lice into the air, so they may spread to another person.
Self Care and Home Treatment
If you do not want to treat head lice with medicine, you may consider a home treatment. But there is little to no proof that home treatments work.
Products to Avoid
Never use products that can cause fire (flammable products) to kill lice or remove nits. Such products include kerosene or gasoline. Do not use products made for animals, such as flea shampoos.
Essential Oils
Natural plant oils, such as limonene and thymols, damage the nervous system of insects when used in insecticide products. Based on this idea, some essential oils were thought to be useful in preventing head lice infestation or killing lice on the scalp. But these products are not produced with the same standards as medicines. Essential oils are not regulated the same way and may cause allergic reactions.
Household Cleaning
Lice most often do not live past a day or two without feeding from a human scalp. And eggs cannot survive without the warmth near the scalp. So the chance of lice staying alive on household items is small.
Still, it is a good idea to clean items that an affected person has used in the past two days. Follow these tips:
Wash items in hot water. Wash bedding, stuffed animals, and clothing in hot, soapy water at least 130 degrees Fahrenheit (54.4 degrees Celsius). Dry on high heat.
Soak hair care items in hot water. Clean combs, brushes, and hair items by soaking them in hot, soapy water for 5 to 10 minutes.
Seal items in plastic bags. Seal items that cannot be washed in plastic bags for two weeks.
Vacuum. Go over the floor and furniture, mainly vacuuming the places where the person with lice has been sitting or lying down.
Prevention
You can stop the spread of lice by avoiding hair and head contact between people. The chance of spreading head lice from items that come in contact with the hair or head is small, but you can lower your risk of getting head lice by taking some precautions.
Do | Don't |
Use protective headgear for sports and bicycling | Share brushes, ribbons, or clips |
Keep hair away from contact during activities | Share hats or scarves |
Clean shared items after exposure | Encourage hair contact during sports or play |
Vacuum furniture where affected person sat | Lie on beds or pillows recently used by someone with lice |
Share fabric items used by a person with lice in the two days before treatment |
Importantly, do use or allow your child to use protective headgear for sports or bicycling. Do not let a fear of head lice stop you from using these important safety items.
Conclusion
Head lice are a common, treatable condition that affects children and adults worldwide. They are not a sign of poor hygiene and do not spread disease, but they do cause significant itching and discomfort. The good news is that with proper treatment — whether over-the-counter permethrin, prescription spinosad, or thorough wet combing — head lice can be eliminated. Remember to follow up with a second treatment if directed, and involve your healthcare provider if the first treatment does not work.
If you or your child has persistent itching, visible nits near the scalp, or sores from scratching, schedule an appointment with your healthcare provider for proper diagnosis and treatment. Early treatment prevents the infestation from spreading to other family members.
FAQ
What are head lice?
Head lice are tiny insects, about the size of a sesame seed, that feed on human blood — most often from the scalp. They are found worldwide and infect hair of any length or type. They are not a sign of poor hygiene and do not spread diseases.
How do you get head lice?
Head lice spread most often through direct head-to-head contact. They crawl from one person's hair to another but cannot jump or fly. Less commonly, they can spread through shared items like hats, brushes, towels, or pillows. Household pets do not spread head lice.
What are the symptoms of head lice?
The most common symptom is itching, though it may take 4 to 6 weeks to develop in a first-time infestation. You may see small tan or gray lice that move quickly, or nits (eggs) stuck to hair shafts near the scalp. Scratching can cause small sores that may become infected.
How do you know if it's lice or dandruff?
Nits are firmly attached to the hair shaft, usually within 1/4 inch of the scalp. Dandruff flakes are loose and fall off easily. Nits found more than 1/4 to 3/8 inch from the scalp are likely empty or dead. A magnifying lens or healthcare professional can confirm the diagnosis.
How do you get rid of head lice?
Treatment options include over-the-counter permethrin or ivermectin lotion, prescription spinosad or malathion, or oral ivermectin. Most treatments require a second application 7 to 10 days later to kill newly hatched lice. Wet combing with a nit comb is also effective.
Do over-the-counter lice treatments always work?
OTC treatments can fail if lice have developed resistance in your area, if the product is not used correctly, or if the second treatment is skipped. If an OTC treatment used correctly has failed, a healthcare provider may prescribe spinosad, malathion, or oral ivermectin.
How long does head lice treatment take?
Most treatments require a second application 7 to 10 days after the first to kill newly hatched nymphs. After treatment, continue combing out nits every 2 to 3 days for 2 to 3 weeks until no nits remain on the scalp.
Can head lice go away on their own?
Head lice will not go away on their own without treatment. The insects feed on blood from the scalp and continue to lay eggs (up to 10 per day) until the infestation is treated. Left untreated, lice can spread to close contacts.
Are home remedies like mayonnaise or essential oils effective?
There is little to no proof that home treatments like mayonnaise, margarine, petroleum jelly, or essential oils work against head lice. Never use flammable products like kerosene or gasoline, and never use flea shampoos made for animals.
How do you clean your home after head lice?
Lice usually die within a day or two without feeding from a human scalp. Wash bedding, clothing, and stuffed animals in hot soapy water (at least 130°F) and dry on high heat. Soak combs and brushes in hot soapy water for 5 to 10 minutes. Seal unwashable items in plastic bags for two weeks and vacuum floors and furniture.
Can you prevent head lice?
You can reduce risk by avoiding head-to-head contact, not sharing brushes, hats, scarves, or hair accessories, and not lying on pillows or furniture recently used by someone with lice. However, do still use protective headgear for sports and bicycling — do not let fear of lice stop you.
Related Reading
Body Lice: Symptoms, Causes, and Treatment explains body lice, which live in clothing and spread differently.
Pubic Lice (Crabs) Guide: Symptoms, Causes, Diagnosis, and Treatment covers pubic lice and how they are diagnosed and treated.
Scabies: Complete Guide to Symptoms, Treatment, and Preventing It From Coming Back explains another itchy skin infestation caused by tiny mites.
Dandruff: Symptoms, Causes & How to Treat It — Complete Guide describes dandruff flakes, which are often mistaken for lice eggs.
References
Mayo Clinic Staff. Head lice - Symptoms and causes. Mayo Clinic. December 16, 2025. https://www.mayoclinic.org/diseases-conditions/head-lice/symptoms-causes/syc-20356180
Mayo Clinic Staff. Head lice - Diagnosis and treatment. Mayo Clinic. December 16, 2025. https://www.mayoclinic.org/diseases-conditions/head-lice/diagnosis-treatment/drc-20356186
Pariser DM, Meinking TL, Bell M, Ryan WG. Topical 0.5% ivermectin lotion for treatment of head lice. N Engl J Med. 2012;367(18):1687-1693. PMID 23113480. https://doi.org/10.1056/NEJMoa1200107
Mohammadi J, Azizi K, Alipour H, et al. Frequency of pyrethroid resistance in human head louse treatment: systematic review and meta-analysis. Parasite. 2021;28:86. PMID 34935614. https://doi.org/10.1051/parasite/2021083
Nofal A. Oral ivermectin for head lice: a comparison with 0.5 % topical malathion lotion. J Dtsch Dermatol Ges. 2010;8(12):985-988. PMID 20718901. https://doi.org/10.1111/j.1610-0387.2010.07487.x
Centers for Disease Control and Prevention. About Head Lice. CDC. June 4, 2024. https://www.cdc.gov/lice/about/head-lice.html
Centers for Disease Control and Prevention. Clinical Care of Head Lice. CDC. January 31, 2025. https://www.cdc.gov/lice/hcp/clinical-care/index.html
Further reading: American Academy of Pediatrics. Red Book Online. American Academy of Pediatrics. Accessed October 30, 2026. https://publications.aap.org/redbook.
Medical disclaimer
This article is for general informational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about any medical condition.
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