Do I have lice? A two minute symptom check and flow chart

Written for parents checking a child or themselves. Based on CDC and American Academy of Pediatrics diagnosis guidance; sources are listed at the bottom. Cartwheel makes Nit Happens, so the treatment step mentions it, labeled as such.

The two minute lice checker

The whole flow chart, written out

1. Start: why are you checking?
   • My child is scratching, or I am. Go to step 1. Itching is a clue, not a diagnosis. In a first infestation it can take four to six weeks to start, and many itchy scalps are dry skin, eczema or a new shampoo.
   • A notice came home from school or camp. Go to step 1, and repeat the check every two to three days for two weeks. Do not treat "just in case": the AAP advises against treating anyone who does not have live lice or nits close to the scalp.
   • I saw something in the hair. Go to step 2.
2. Step 1: do a proper check, not a glance. Wet the hair, add plenty of conditioner, and pull a fine tooth comb (a metal nit comb if you have one) from the scalp to the ends in narrow sections, wiping the comb on a white paper towel after every pass. Look hardest behind the ears and at the nape of the neck, under bright light. Ten minutes is enough for most heads. Full instructions, including how to check yourself.
3. Step 2: what landed on the paper towel or what did you see?
   • A live insect that moves, tan to grayish, 2 to 3 mm, six legs, usually seen near the scalp. Yes, that is head lice. Go to "You found lice" below.
   • Tiny ovals glued to single hairs, tan, yellow or brown, that have to be pulled down the hair with a fingernail and sit within about a quarter inch (6 mm) of the scalp. Almost certainly an active case. The CDC and AAP treat nits that close to the scalp, with no treatment in the last month, as a sign of live lice. Comb the whole head once more looking for a live louse to be sure, then go to "You found lice."
   • Ovals glued to the hair but more than a quarter inch from the scalp, often white or clear. These are usually hatched or dead eggs from an old case. Not proof of current lice. Comb thoroughly; if no live lice turn up, recheck in two to three days.
   • White or gray flakes that slide along the hair or brush off. Dandruff, dry scalp or hair product. Not lice. Nits do not slide.
   • Nothing at all. No lice today. If there was an exposure or the itching continues, recheck in two to three days, and consider other causes of an itchy scalp.
   • Not sure what you are looking at? Use the comparison table below, or take a photo of the speck on the paper towel next to a coin and compare it with the CDC's images. Dandruff is flat and irregular; a nit is a smooth teardrop with a tiny cap on one end; a louse has legs and moves.
4. You found lice. What now?
   • Treat the person today. Options that do not depend on the lice being susceptible to pesticides are the sensible default, since about 98% of US head lice now resist permethrin and pyrethrins (the Nix and RID ingredients). Cartwheel makes Nit Happens, a pesticide free kit (gel, shampoo, metal comb, gloves, $34.99 per person, ages 3 and up) sold at Walgreens, Amazon and here. Dimethicone products and prescriptions such as spinosad or ivermectin lotion are the other non pyrethroid routes. Under age 3, call your pediatrician first.
   • Check everyone in the household the same day and treat only those with live lice or nits near the scalp. Bedmates of the person with lice are the most likely to have it.
   • Wash the hats, pillowcases, towels and clothing used in the last two days in hot water with a hot dryer cycle; bag what cannot be washed for two weeks; soak combs and brushes in 130 F water for 5 to 10 minutes. No sprays or fogs, and no need to clean the whole house. Lice die within a day or two off a head.
   • Comb every two to three days, and plan on the second application most labels call for around day 7 to 9, which catches lice that hatched after the first round. Nits left behind after treatment are normal; live lice after a completed second treatment are the signal to switch to a different type of product or call the pediatrician.
   • School: the AAP and CDC say a child with lice can finish the school day, be treated that evening and return the next morning. No nit policies are not recommended.

Louse, nit or dandruff? Side by side

Signs that point to lice (and signs that do not)

• Points to lice: itching concentrated at the nape and behind the ears, worse at night; a tickling or crawling feeling; small red bumps or scratch marks at the hairline and neck; a recent sleepover, camp or classroom case.
• Does not by itself: an itchy scalp all over, flakes, a sore or dry scalp, or a school notice. Only finding a louse or a fresh nit confirms it. Misdiagnosis is common: in one study of 614 specimens that parents, nurses and doctors submitted as lice, about four in ten were not lice or nits at all, and many of the eggs that were real had already hatched [3].

Questions parents ask

How do I know if I have lice or dandruff?

Try to move it. Dandruff slides along the hair or brushes off; a nit is glued on and has to be pulled down the strand with a fingernail. Nits are also oval, tan and sit on one side of the hair within a quarter inch of the scalp. Dandruff is flat, white and anywhere.

Can you have lice and not itch?

Yes. Itching is an allergic reaction to louse saliva and can take four to six weeks to appear the first time. Some people never itch much. That is why checking the hair matters more than asking whether it itches.

Do nits mean you have lice?

Nits within a quarter inch of the scalp, in hair that has not been treated in the last month, are treated as an active case by the CDC and AAP. Nits farther down the hair shaft are usually hatched or dead and do not need treatment on their own.

How do I check myself for lice?

Use two mirrors or your phone on selfie video with the flash on to see the nape of your neck and behind your ears, then wet comb with conditioner and a metal comb, wiping each pass on a white paper towel. The towel tells you more than the mirror. Step by step here.

Should I treat before I find anything, just to be safe?

No. The AAP advises against treating anyone who does not have live lice or nits close to the scalp. Pesticide treatments add exposure and resistance for no benefit, and even non pesticide treatments are a waste if there are no lice. Check every two to three days for two weeks after an exposure instead.

What if I am still not sure?

Comb again in two or three days, or take the paper towel to your pediatrician or school nurse, who can identify a louse or nit in seconds. Many pediatric offices will look at a clear photo.

Sources

1. Centers for Disease Control and Prevention. Head lice: about, diagnosis and treatment. cdc.gov/lice.
2. Nolt D, Moore S, Yan AC, Melnick L; American Academy of Pediatrics. Head Lice. Pediatrics, 2022 (clinical report): diagnosis by live louse or nits within 1/4 inch, no treatment without evidence of active infestation, school attendance guidance.
3. Pollack RJ, Kiszewski AE, Spielman A. Overdiagnosis and consequent mismanagement of head louse infestations in North America. Pediatric Infectious Disease Journal, 2000: of 614 specimens submitted, 250 were not lice or nits, and many eggs were hatched or dead.
4. Gellatly KJ et al. Expansion of the knockdown resistance frequency map for human head lice in the United States. Journal of Medical Entomology, 2016: 98.3% of lice sampled carried kdr mutations.

This page is general information, not medical advice. Cartwheel makes and sells Nit Happens. If a child is under 3, pregnant or nursing family members are affected, or the scalp is broken or infected, call your pediatrician or doctor before treating.