My Child Was Exposed to Lice. What Do I Do in the Next 24 Hours?
By Joanna Shu, founder of Cartwheel. Updated November 12, 2026. Cartwheel makes Nit Happens, and that is disclosed wherever it appears below.
Short answer: Check your child's head tonight with a fine metal comb on wet, conditioned hair. If you find a live louse or nits within a quarter inch of the scalp, treat that child tonight. If you find nothing, do not treat; check again in 3 to 4 days and once more around day 10, because eggs laid during the exposure take 6 to 9 days to hatch. Lice do not jump or fly, so the exposure itself is not an emergency; the comb check is.
Do not treat a child who has no lice "just in case." The American Academy of Pediatrics and the CDC both advise against it, and it is the main way families waste money and build resistance.
What the exposure email actually means
A classroom notice means one or more children in the room had live lice. It does not mean your child has them. Head lice crawl; they cannot jump, fly or swim. They move by head to head contact, which is why sleepovers, huddles over a screen, and hugs spread them, and sitting across a classroom does not. A louse off a head dies within a day or two, and nits (eggs) cannot hatch away from the warmth of a scalp. So the risk from a shared coat hook or a classroom rug is low, and the risk from the friend your child's head was touching is real.
Tonight: the five minute check
- Wet the hair and work in a handful of ordinary conditioner. Wet, slippery hair holds lice still and makes nits easier to see.
- Sit under bright light. A phone flashlight held by another adult works.
- Comb from the scalp outward with a fine metal lice comb, section by section, wiping the comb on a white paper towel after every pass. Pay attention to behind the ears and the nape of the neck.
- Look at the paper towel. A live louse is grayish tan, the size of a sesame seed, and moves. A nit is a tiny oval glued to one hair at an angle, usually within a quarter inch of the scalp; it does not flick off the way dandruff does.
- Decide. Live lice or nits close to the scalp mean treat tonight. Nothing means no treatment; set reminders for the rechecks.
Not sure what you are looking at? The two minute checker walks through louse vs nit vs dandruff with photos.
If you find lice
- Treat the child who has them tonight. A pesticide-free kit such as Nit Happens (ours) kills lice and nits by coating and dehydrating them, and the metal comb removes them; it works on the permethrin-resistant lice that now make up about 98% of US lice. Nix and RID are labeled for ages 2 and up but fail often for that reason.
- Check every other head in the house the same night. Treat only the people who have lice. The one exception the CDC mentions is a bedmate of the infested child, whom some experts choose to treat as well.
- Wash the bedding and the clothes worn in the last two days in hot water and dry on high. Bag stuffed animals and hats for two days. Soak combs and brushes in hot water. That is all; lice are not living in your carpet.
- Tell the school nurse and the parents of close friends. It is the single most useful thing you can do, and it is not a confession. Lice have nothing to do with cleanliness.
- Repeat the treatment 7 days later. Any egg that survives the first round hatches within that week; the second application catches it before it can lay eggs of its own.
If you find nothing
- Do not use a lice product. Neither the AAP nor the CDC recommends treating a child without lice, and the pesticide products are not harmless.
- Recheck in 3 to 4 days and again around day 10. Eggs laid during the exposure hatch between day 6 and day 9, and a newly hatched nymph is tiny and easy to miss on the first look.
- Reduce the chance of a second exposure while the classroom clears: hair tied back, braided or in a bun for the next two weeks, no shared hats, helmets or hairbrushes, and heads apart during screen time and selfies.
- A leave-in detangler keeps hair smooth and easier to keep up; the Nit Happens School Day Spray is the one we make for that. It is a hair care product, not a treatment.
The 14 day timeline
| Day | What to do | Why |
|---|---|---|
| Day 0 (the email) | Wet comb check of every child | Finds live lice now |
| Day 3 to 4 | Second wet comb check | Catches lice missed the first time |
| Day 7 | If you treated: second application | Kills nymphs hatched since day 0 |
| Day 10 | Final wet comb check | Eggs laid at exposure have all hatched by now |
| Day 14 | Back to normal | Any lice from the exposure would be visible by now |
Found lice tonight? Nit Happens is the pesticide-free kit with an IRB approved clinical study: 89% lice free at day 15 counting everyone enrolled, 95.8% when two participants the investigators judged to be re-infestations are excluded. Ages 3 and up, $34.99 per person, HSA and FSA eligible, at Walgreens nationwide and on Amazon.
See the kit Buy at Walgreens Buy on AmazonQuestions parents ask
Should I treat my child for lice after an exposure, to be safe?
No. Treat only if you find live lice or nits within a quarter inch of the scalp. The AAP and CDC both advise against preventive treatment: it does not stop an infestation that has not happened, and repeated pesticide exposure is a real cost.
How soon after exposure would I see lice?
Live adult lice can be found the same day if they transferred. Eggs laid during the exposure hatch in 6 to 9 days, so a nymph can appear up to about day 10. Check tonight, again at day 3 to 4, and again around day 10.
Can my child go to school after a lice exposure?
Yes. Exposure is not an infestation. Even a child with live lice can finish the school day under AAP and CDC guidance, be treated at home, and return the next day. Check our school nurse toolkit for the policy language.
Do I need to clean the whole house after a lice exposure?
Only if you found lice, and even then only bedding, recent clothes, hats, hair tools and stuffed animals from the last two days. Lice die within a day or two off a head. Fogging and furniture sprays are not recommended by the CDC.
Can lice spread from a coat hook, bus seat or classroom rug?
Rarely. Lice crawl and need a warm head within a day or two. Almost all transmission is head to head contact. Hats, brushes and pillows shared within a day are the only objects worth worrying about.
My toddler was exposed. Can I use a lice treatment on a 2 year old?
Do the wet comb check first; wet combing is safe at any age. If you find lice, Nix and RID are labeled from age 2, ivermectin lotion from 6 months, and Nit Happens from age 3. See which over the counter lice treatments are safe for toddlers.
Related guides
- Do I have lice? A two minute check
- How to prevent lice at school, camp and sleepovers
- Best lice treatment 2026, ranked by the evidence
- School nurse lice toolkit
- Nit Happens instructions for use
Sources
- American Academy of Pediatrics, Head Lice clinical report, Pediatrics 2022 (no exclusion from school; no treatment of children without lice).
- CDC, Head Lice: Prevention and Control, and Treatment (transmission by head to head contact; survival off the host; bedmates).
- Gellatly KJ et al. J Med Entomol 2016 (98.3% knockdown resistance frequency in US head lice).
- Villar and Rubio Rivera, H.A.L.T. clinical study, 2020, commissioned by Arbor Development; Cartwheel is the licensee. doi:10.5281/zenodo.23510395.