Head Lice FAQ: Answers to Common Questions
General Lice Questions
What are head lice?
Head lice (Pediculus humanus capitis) are tiny, wingless insects that live on the human scalp and feed on small amounts of blood. They are a very common nuisance, especially among school-aged children, but they do not spread disease and are not a sign of poor hygiene. Adult lice are about the size of a sesame seed and move only by crawling; they cannot jump or fly.
What do head lice look like?
Adult lice are roughly 2 to 3 mm long (about the size of a sesame seed), tan to grayish-white, with six legs. Young lice (nymphs) are smaller and paler, and the eggs (nits) look like tiny yellowish-white or clear specks glued to the hair shaft near the scalp. Lice move quickly and avoid light, so live bugs are harder to spot than nits.
What are nits (lice eggs)?
Nits are lice eggs: tiny oval specks, under 1 mm, that a female louse cements firmly onto a hair shaft close to the scalp. Live, unhatched nits usually sit within about 6 mm of the scalp and look tan or coffee-colored, while empty or hatched shells look white and sit farther out as the hair grows. Because they are glued on, nits do not flick off the way dandruff does.
What’s the difference between lice and dandruff?
Dandruff flakes are loose and brush or shake off easily; nits are firmly glued to the hair shaft and stay put when you try to slide them. Dandruff is flaking of the scalp, while nits are teardrop-shaped eggs attached to individual hairs. If a flake slides freely along the hair, it is almost certainly not a nit.
Do lice prefer clean hair or dirty hair?
Neither. Lice do not care whether hair is clean or dirty because they feed on blood, not oil or dirt. Anyone with hair can get them, so an infestation is not a reflection of hygiene or cleanliness. Lice spread mainly through direct head-to-head contact.
Can adults get lice too?
Yes. Head lice are most common in children about 3 to 11 years old, but adults can get them through head-to-head contact, including parents, caregivers, and teachers. Anyone with hair on their scalp can host lice.
Can lice live in eyebrows or eyelashes?
Head lice stay almost entirely on the scalp and do not typically infest eyebrows or eyelashes. Lice found on the lashes are usually a different species (pubic lice), which is a separate situation and, in a child, should be discussed with a healthcare provider. If you think the lashes are affected, see a doctor rather than using scalp treatments near the eyes.
Symptoms and Diagnosis
Does itching always mean I have lice?
No. Itching is a common sign, but it comes from an allergic reaction to lice saliva and can take 4 to 6 weeks to develop the first time, so you can have lice without itching. Itching can also be caused by dry scalp, eczema, or dandruff. The only way to confirm lice is to find a live louse or viable nits.
What’s the best way to find live lice?
Wet-combing is the most reliable method: wet the hair, work in plenty of conditioner, and comb small sections from scalp to tip with a fine-toothed lice comb, wiping it on a paper towel after each stroke. Good lighting helps, and wetting the hair slows the lice down so they are easier to catch. Check the comb and the scalp behind the ears and at the nape of the neck.
Can you have nits without having live lice?
Yes. After successful treatment, empty nit shells often stay glued to the hair even though no live lice remain. Nits found more than about 6 mm from the scalp are usually already hatched or dead. Finding only far-out white nits, with no live lice or eggs near the scalp, usually means an old, resolved infestation.
How long can you have lice before noticing?
Often several weeks. Because the itch is an allergic response that can take 4 to 6 weeks to appear on a first infestation, lice can go unnoticed until numbers build up or someone spots them during combing. Regular checks after a known exposure help catch them earlier.
What are the most common signs of head lice?
The usual signs are an itchy scalp (especially behind the ears and at the nape of the neck), a tickling or crawling feeling, trouble sleeping, and small red irritation from bites. The most definitive sign is seeing live lice or viable nits during a careful comb-through. Not everyone itches, so no itching does not rule lice out.
School, Daycare, and Social
Can my child go to school if they have lice?
In most places, yes. Major pediatric and public-health groups recommend that a child finish the school day, be treated, and return to class, rather than being sent home right away. Lice are a nuisance, not a health hazard, and do not spread disease. Check your school's specific policy, though immediate exclusion is increasingly discouraged.
What are “no-nit policies” and do they work?
"No-nit" policies keep children out of school until every nit is removed. Leading medical and public-health organizations advise against them because they cause children to miss school unnecessarily and do not meaningfully reduce transmission, since many remaining nits are already hatched or dead. Treatment plus normal combing is considered more effective than exclusion.
Should I tell the school if my child has lice?
Letting the school or daycare know is helpful so they can encourage checks among close contacts and reduce spread, even though lice are not a reportable illness. Keeping the tone matter-of-fact helps, since lice are common and not tied to hygiene. Follow your school's communication policy.
How do I prevent lice spreading in a household?
Check everyone in the home for live lice and treat only those who are actually infested. During an active case, avoid head-to-head contact and do not share brushes, combs, hats, or pillows. Wash recently used bedding and worn clothing in hot water and dry on high heat; items that cannot be washed can be sealed in a bag for about two weeks, since lice cannot survive long off the scalp.
How do I avoid reinfestation during sleepovers?
Keep heads from touching during shared sleeping, and have each child use their own pillow and sleeping bag instead of sharing. Avoid swapping hats, hair accessories, and brushes. A quick check in the days after a sleepover helps catch any new lice early.
Safety and “What NOT to Do”
Is it safe to use lice treatments on toddlers or infants?
Not all treatments are labeled for very young children, so for infants and toddlers you should check the product's age guidance and talk to a pediatrician before using any medicated product. Wet-combing with conditioner is a safe, chemical-free option appropriate at any age. When in doubt, ask your child's doctor.
Can I use lice shampoo more than once in a day?
No. Medicated lice treatments should be used exactly as directed on the label; using more than instructed does not work better and can irritate or harm the scalp. Most treatments call for a repeat application after about 7 to 9 days to catch newly hatched lice, not repeated doses in one day. Overusing pesticidal products is unsafe.
Are essential oils safe for lice treatment?
Evidence for essential oils such as tea tree oil as lice treatments is limited, and they are not standardized or regulated for this use. Some can irritate skin or trigger allergic reactions, especially in young children, and a few can be harmful if misused. If you want a non-pesticide approach, thorough wet-combing has the best safety record.
Is it safe to use bleach, kerosene, or bug spray for lice?
No. Never put bleach, kerosene, gasoline, or household or insecticide sprays on the scalp or hair. These are dangerous and can cause chemical burns, poisoning, or fires, and they are not effective lice treatments. Use only products intended for head lice, or remove lice mechanically by combing.
Can I use heat tools (straighteners/blow dryers) to kill lice safely?
Regular blow dryers and straighteners are not a safe or reliable way to kill lice and can burn the scalp, and flat irons cannot reach eggs at the scalp line without risking injury. Some lice salons use specialized, controlled heated-air devices, but that is very different from home tools. Stick to combing and appropriate treatments rather than improvising with heat.