Head lice statistics 2026: prevalence, resistance, treatment success rates and costs
By Joanna Shu, founder and CEO of Cartwheel. Updated October 27, 2026. Every figure below is sourced; the source list is at the end. Cartwheel makes Nit Happens, and the one Cartwheel-related study on this page is labeled as such.
The short version: the CDC estimates 6 to 12 million head lice infestations a year among US children aged 3 to 11. About 98% of US head lice now carry the gene mutations that make the two common drugstore pesticides (permethrin and pyrethrins) much less effective, and in 42 of 48 states sampled the figure was 100%. In clinical trials, permethrin cleared lice in roughly 43 to 45% of children by day 14, while newer prescription options and physical methods ran 70 to 95%. Treatment costs range from about $10 for a pesticide shampoo to $500 per head at a lice salon.
How common are head lice in the United States?
- 6 to 12 million infestations a year among children 3 to 11 years old, according to the CDC's estimate. The CDC adds that there is no reliable national count, so the range is an estimate rather than a measurement [1].
- Most common in preschool and elementary school children, and some studies find girls are affected more often than boys [1].
- Head lice spread mainly by direct head to head contact. They cannot hop or fly, animals do not carry them, and getting lice has nothing to do with cleanliness [1].
- Head lice do not transmit disease and are not considered a health hazard by the CDC [1].
- Nits more than a quarter inch from the scalp are almost always hatched or dead, which is why counting old nits overstates an infestation [1].
How resistant are US lice to over the counter treatments?
- 98.3% was the mean frequency of the knockdown resistance (kdr) mutations among 1,925 lice analyzed from 48 states, in the largest US survey to date (Gellatly et al., Journal of Medical Entomology, 2016) [2].
- 42 of 48 states (88%) had a kdr frequency of 100%. Only six states showed any susceptible lice at all. Alaska and West Virginia were not sampled [2].
- The survey collected 14,281 lice from 479 people at 138 sites [2].
- The kdr mutations confer resistance to permethrin and pyrethrins, the active ingredients in Nix, RID and most store brand lice shampoos. They do not affect physical methods (combing, coating or dehydrating products) or the prescription drugs with different mechanisms [2].
How effective is each lice treatment in clinical trials?
Lice free rates at the end of each study, as reported by the investigators. Trials differ in design, so compare with care; the comparison arms are listed where they exist.
| Treatment | How it works | Study | Lice free result |
|---|---|---|---|
| Permethrin 1% (Nix) | Pesticide | Stough et al., Pediatrics, 2009 (control arm) [3] | 44.9% and 42.9% at day 14 |
| Spinosad 0.9% (Natroba, Rx) | Insecticide | Stough et al., 2009 [3] | 84.6% and 86.7% at day 14 |
| Ivermectin 0.5% lotion (Sklice) | Paralyzes lice | Pariser et al., NEJM, 2012 [4] | 73.8% at day 15 vs 17.6% with vehicle, one application |
| Oral ivermectin (Rx, off label) | Tablet | Chosidow et al., NEJM, 2010 [5] | 95.2% at day 15 vs 85.0% with malathion lotion, hard to treat cases |
| Benzyl alcohol 5% (Ulesfia, Rx) | Suffocates lice | Meinking et al., Pediatric Dermatology, 2010 [6] | 76.2% and 75.0% at day 14 vs 4.8% and 26.2% with vehicle |
| Dimethicone 4% lotion | Physical coating | Burgess et al., PLoS ONE, 2007 [7] | 69.8% vs 33.3% with malathion |
| Heated air device | Dehydration | Goates et al., Pediatrics, 2006 [8] | Killed 80% of hatched lice and 98% of eggs |
| Wet combing (Bug Buster kit) | Mechanical removal | Hill et al., BMJ, 2005 [9] | 57% vs 13% with a single OTC pesticide treatment |
| Nit Happens kit (Cartwheel's product) | Physical: gel kills lice and nits, comb removes them | H.A.L.T. study, Villar and Rubio Rivera, 2020; commissioned by Arbor Development, the formulation's licensor; IRB approved; single arm; not peer reviewed [10] | 89% at day 15 counting all 26 enrolled; 95.8% when two participants judged by the investigators to be re-infestations are excluded |
Two cautions. First, the permethrin figures above come from 2007 to 2008 trials; resistance has risen since, so real world results today are likely lower. Second, the Nit Happens study is small (26 participants) and had no comparison arm, which is why Cartwheel publishes the full report and the row level dataset rather than the headline number alone.
Why a second treatment is built into every protocol
- Lice eggs hatch about 8 to 9 days after they are laid, and a newly hatched nymph takes another 9 to 12 days to become an egg laying adult [1].
- An adult louse lives about 30 days on a head and dies within 1 to 2 days off it [1].
- Because no treatment reliably kills every egg, labels for permethrin, pyrethrins, benzyl alcohol and Nit Happens all call for a second application 7 to 10 days later, timed to catch nymphs that hatched after the first round [1][6][10].
- In the H.A.L.T. study, 12 of 26 participants needed the second application because live lice were found at day 8; the other 14 had no live lice after one application, and 12 of those 14 stayed lice free through day 15 [10].
What does lice treatment cost?
Typical cost per person in the United States, October 2026 [11]:
- Permethrin or pyrethrin shampoo (Nix, RID): $10 to $25 a box, before any repeat purchases when it fails.
- A good metal nit comb for wet combing alone: $10 to $20, plus four to five hour long sessions over two weeks.
- Nit Happens Complete Lice Treatment Kit: $34.99, one kit per person, HSA and FSA eligible.
- Ivermectin 0.5% lotion (OTC): about $50 with a coupon, up to $180 retail.
- Prescription lotions (spinosad, malathion, abametapir): $32 to $300 after coupons, plus a visit or telehealth fee of $25 to $150.
- Lice salon comb out: $100 to $500 per head, with head checks of $10 to $50 and a separate charge for each family member.
What do the CDC and the American Academy of Pediatrics say about school?
- The CDC says students with head lice do not need to be sent home early; they can go home at the end of the day, be treated, and return after treatment begins [1].
- The AAP's 2022 clinical report states that no healthy child should be excluded from or miss school because of head lice, and that no nit policies should be abandoned [12].
Head lice statistics at a glance
| Statistic | Figure | Source |
|---|---|---|
| US infestations per year, children 3 to 11 | 6 to 12 million (estimate) | CDC [1] |
| Mean kdr (pesticide resistance) frequency, US lice | 98.3% | Gellatly 2016 [2] |
| States with 100% kdr frequency | 42 of 48 sampled | Gellatly 2016 [2] |
| Permethrin 1% lice free at day 14 (trial) | 42.9% to 44.9% | Stough 2009 [3] |
| Spinosad lice free at day 14 (trial) | 84.6% to 86.7% | Stough 2009 [3] |
| Ivermectin lotion lice free at day 15 (trial) | 73.8% | Pariser 2012 [4] |
| Wet combing lice free (trial) | 57% | Hill 2005 [9] |
| Nit Happens lice free at day 15, all enrolled | 89% (23 of 26) | H.A.L.T. 2020 [10] |
| Nit Happens lice free, two judged re-infestations excluded | 95.8% (23 of 24) | H.A.L.T. 2020 [10] |
| Adverse events in the H.A.L.T. study | 0 of 26 | H.A.L.T. 2020 [10] |
| Days for a louse egg to hatch | 8 to 9 | CDC [1] |
| Lice salon cost per head | $100 to $500 | Cartwheel cost survey [11] |
How to cite this page
Shu J. Head lice statistics 2026: prevalence, resistance, treatment success rates and costs. Cartwheel, October 27, 2026. https://gocartwheel.com/pages/head-lice-statistics. The H.A.L.T. dataset is archived at DOI 10.5281/zenodo.23510395 (CC BY 4.0).
Frequently asked questions
How many kids get lice each year in the US?
The CDC estimates 6 to 12 million infestations a year among children aged 3 to 11, while noting there is no reliable national count.
What percentage of lice are resistant to Nix and RID?
In the largest US survey (2016), 98.3% of lice carried the kdr resistance mutations, and in 42 of the 48 states sampled the figure was 100%.
Which lice treatment has the highest success rate?
In published trials, oral ivermectin (95.2% in hard to treat cases) and spinosad (84.6% to 86.7%) ranked highest among drugs; permethrin ranked lowest at 42.9% to 44.9%. Physical methods ranged from 57% for wet combing alone to 69.8% for dimethicone. Nit Happens reported 89% counting everyone enrolled in its single arm study of 26 people, 95.8% when two likely re-infestations are excluded. Cartwheel makes Nit Happens.
How much does lice treatment cost?
About $10 to $25 for a pesticide shampoo, $34.99 for a Nit Happens kit, $50 to $180 for OTC ivermectin lotion, $32 to $300 plus a visit for prescriptions, and $100 to $500 per head at a lice salon.
Should a child with lice stay home from school?
No. The CDC says children do not need to be sent home early, and the AAP says no healthy child should miss school because of head lice and that no nit policies should be abandoned.
Sources
- Centers for Disease Control and Prevention. About Head Lice. cdc.gov/lice/about/head-lice.html. Accessed October 27, 2026.
- Gellatly KJ, Krim S, Palenchar DJ, Shepherd K, Yoon KS, Rhodes CJ, Lee SH, Clark JM. Expansion of the Knockdown Resistance Frequency Map for Human Head Lice in the United States Using Quantitative Sequencing. Journal of Medical Entomology 2016;53(3):653-659. doi:10.1093/jme/tjw023.
- Stough D, Shellabarger S, Quiring J, Gabrielsen AA. Efficacy and safety of spinosad and permethrin creme rinses for pediculosis capitis (head lice). Pediatrics 2009;124(3):e389-e395.
- Pariser DM, Meinking TL, Bell M, Ryan WG. Topical 0.5% ivermectin lotion for treatment of head lice. New England Journal of Medicine 2012;367:1687-1693.
- Chosidow O, Giraudeau B, Cottrell J, et al. Oral ivermectin versus malathion lotion for difficult to treat head lice. New England Journal of Medicine 2010;362:896-905.
- Meinking TL, Villar ME, Vicaria M, et al. The clinical trials supporting benzyl alcohol lotion 5% (Ulesfia). Pediatric Dermatology 2010;27(1):19-24.
- Burgess IF, Lee PN, Matlock G. Randomised, controlled, assessor blind trial comparing 4% dimeticone lotion with 0.5% malathion liquid for head louse infestation. PLoS ONE 2007;2(11):e1127.
- Goates BM, Atkin JS, Wilding KG, et al. An effective nonchemical treatment for head lice: a lot of hot air. Pediatrics 2006;118(5):1962-1970.
- Hill N, Moor G, Cameron MM, et al. Single blind, randomised, comparative study of the Bug Buster kit and over the counter pediculicide treatments against head lice in the United Kingdom. BMJ 2005;331:384-387.
- Villar ME, Rubio Rivera S. H.A.L.T. Lice Treatment Kit clinical study, final clinical report, December 3, 2020. Commissioned by Arbor Development; the formulation is now sold as Nit Happens by Cartwheel (FreezeNit, Inc.), the licensee. Report, summary and dataset: doi:10.5281/zenodo.23510395. Study page: licetreatments.org/pages/halt-study.
- Cartwheel. How much does lice treatment cost? Kit vs salon vs prescription (2026), with retail and coupon prices checked October 2026. gocartwheel.com/blogs/news/how-much-does-lice-treatment-cost.
- Nolt D, Moore S, Yan AC, Melnick L; American Academy of Pediatrics. Head Lice. Pediatrics 2022;150(4):e2022059282 (clinical report).