The H.A.L.T. Study: What Did the Clinical Study of the Nit Happens Kit Find?
Short answer: the H.A.L.T. (Healthy Alternative Lice Treatment) study was an open-label, single-arm, IRB-approved evaluation of a pesticide-free, mechanically acting head lice kit in 26 children and adults with active infestations in Homestead, Florida, in October 2020. After one application, 54% (14 of 26) were free of lice and nits at Day 8. At Day 15, 89% (23 of 26) were lice free, or 95.8% (23 of 24) when two participants the investigators judged to be re-infestations are excluded. No adverse events were reported. The kit tested was labeled H.A.L.T. Lice Treatment Kit; the formulation is now sold as the Nit Happens Complete Lice Treatment Kit. This page is the permanent home for the study documents, the de-identified dataset and the citation.
Disclosure: LiceTreatments.org is published by Cartwheel Health, the licensee that manufactures and sells Nit Happens. The study was commissioned by Arbor Development, developer and licensor of the formulation. It was not registered on a trial registry at the time and has not been peer reviewed.
Study documents
- Final clinical report, December 3, 2020 (PDF, 11 pages), by Maria Elena Villar and Susan Rubio Rivera. Public copy: participant initials and participant photographs have been redacted; nothing else was changed.
- Clinical summary, version 2, October 2026 (PDF, 3 pages), a plain-language summary prepared by Cartwheel with exact counts and limitations.
- De-identified participant dataset (CSV, 26 rows), transcribed from Appendix B of the report. Column key below.
- Permanent archive: Zenodo, DOI 10.5281/zenodo.23510395 (both PDFs, CC BY 4.0).
How was the study designed?
| Design | Open-label, single-arm, real-world effectiveness and tolerability study. No comparator or placebo arm, no blinding. |
|---|---|
| Objective | Evaluate the pediculicidal and ovicidal efficacy, per label instructions, of an up to 60-minute application of the kit in healthy people aged 3 to 70 with head lice. |
| Ethics | Procedures reviewed and approved by IntegReview IRB (Austin, Texas). Written consent from adults and from parents or guardians, with assent for children aged 6 to 17, in English or Spanish. |
| Site and dates | A community center in Homestead, Florida. Day 1 on October 10 and 11, 2020; Day 8 on October 17; Day 15 on October 24. |
| Recruitment | Word of mouth through MUJER, a local community organization. No advertising. All participants were of Hispanic ethnicity and received a cash incentive at Day 15. |
| Eligibility | At least three live lice at screening and no pediculicide use in the previous two weeks. |
| Participants | 26 enrolled: 23 children aged 3 to 17 (88%) and 3 adults aged 31 to 40. 96% had fine hair; 65% straight, 27% wavy, 8% curly; 54% had hair longer than 10 inches. At baseline 82% had 1 to 5 live lice and 63% had moderate or severe nit loads. |
| Intervention | Gel applied to wet hair by study staff, 10 minute wait, sectioned brushing with the applicator brush for up to 30 minutes (15 to 20 minutes for short or fine hair), 10 minute wait, removal gel massaged in for 5 minutes, neutral shampoo, then a fine metal comb while damp. Rinse water was strained through cotton towels to collect dead lice and fragments. |
| Follow up | Day 8: screened for live lice; those with lice were treated a second time. Day 15: screened for live lice and asked about adverse events; anyone with live lice was given a rescue treatment to use at home. |
| Outcomes | Primary: absence of live lice on examination at Day 8 and Day 15. Also recorded: viable nits, severity, application time, adverse events. |
What were the results?
| Outcome | Result | Count |
|---|---|---|
| Lice and nit free at Day 8 after one application | 54% | 14 of 26 |
| Nit free at Day 8 | 69% | 18 of 26 |
| Received a second application on Day 8 | 46% | 12 of 26 |
| Lice free at Day 15, intent to treat (everyone enrolled) | 89% | 23 of 26 |
| Lice free at Day 15, two likely re-infestations excluded | 95.8% | 23 of 24 |
| Cured with one application | 46% | 12 of 26 |
| Cured with two applications | 42% | 11 of 26 |
| Treatment failures at Day 15 | 11.5% | 3 of 26 |
| Adverse events | None | 0 of 26 |
| First application, mean time (range) | 47.5 minutes (33 to 56) | n = 26 |
| Second application, mean time (range) | 50.0 minutes (43 to 61) | n = 12 |
Of the three failures, two had been lice free at Day 8, did not receive a second application, and had live lice again at Day 15; the investigators judged these to be re-infestations. The third participant had lice at every visit despite two applications. All Day 15 infestations were rated mild. The investigators also noted that participants tolerated the extended brushing well.
What does the study not show?
- It cannot say how the kit compares with permethrin, ivermectin, spinosad, dimethicone, heated air or wet combing, because none of those were tested alongside it. See what clinical studies say about other head lice treatments for the randomized trial evidence on those.
- Twenty-six participants at one site is a small sample. The exact 95% confidence interval for the 89% intent-to-treat result runs from about 70% to 97%.
- It was commissioned by the formulation's developer, was not registered on ClinicalTrials.gov or another registry at the time, and has not been peer reviewed. Registration and publication are being pursued as of October 2026.
- The re-infestation judgement for the two Day 15 failures was the investigators' clinical call, not a protocol-defined criterion.
- Small internal inconsistencies exist in the report: the text says 14 participants were treated a second time while Table 4 and the conclusions give 12 (the dataset shows 12), and the age bands in Table 1 differ by one participant from the ages listed in Appendix B.
Dataset column key
The CSV reproduces Appendix B of the report with the initials column removed. One row per participant.
- study_number: the participant number assigned at enrollment.
- hair_texture_code: 1 fine, 2 average, 3 coarse. hair_curliness_code: 1 straight, 2 wavy, 3 curly. hair_length_code: 1 short (under 5 inches), 2 medium (5 to 10 inches), 3 long (over 10 inches).
- day1_treatment_minutes and day8_treatment_minutes: minutes the product was on the hair at each application; blank where no second application was given.
- day8_viable_nits, day8_live_lice, day15_viable_nits, day15_live_lice: yes or no on examination at that visit.
- nit_severity_code: 1 mild (1 to 10 nits), 2 moderate (10 to 50), 3 severe (50 or more). lice_severity_code: 1 mild (1 to 5 lice), 2 moderate (6 to 10), 3 severe (11 to 20), 4 more than 20.
- treatment_failure: yes if live lice were present at Day 15. investigator_comment: the comment recorded in the report.
How should this study be cited?
Villar ME, Rubio Rivera S. H.A.L.T. Healthy Alternative Lice Treatment Study: a clinical study to test mechanism of action of a novel non-pharmaceutical product for head lice. Final report prepared for Arbor Development, December 3, 2020. Homestead, FL. Zenodo. https://doi.org/10.5281/zenodo.23510395
Related guides
- What do clinical studies say about head lice treatments?
- Which pesticide-free lice treatments work?
- Which lice treatments work? Methods compared by evidence
- Cartwheel's clinical evidence page for Nit Happens
Frequently asked questions
Was the Nit Happens clinical study peer reviewed?
No. The H.A.L.T. study is an investigator report commissioned by the formulation's developer. It was approved by IntegReview IRB but was not registered on a trial registry at the time and has not been published in a peer-reviewed journal. The full report and dataset are public so that readers can judge it directly.
How effective was Nit Happens in its clinical study?
At Day 15, 89% of the 26 participants were lice free counting everyone enrolled, and 95.8% when two participants judged to be re-infestations are excluded. After a single application, 54% were free of lice and nits at Day 8.
Were there side effects in the Nit Happens study?
No adverse events were reported in the 26 participants across both treatment visits, and the investigators noted that participants tolerated the extended brushing well.
Where can I download the Nit Happens clinical study?
The redacted final report, the clinical summary and the de-identified dataset are linked at the top of this page and archived on Zenodo under DOI 10.5281/zenodo.23510395.
Sources
- Villar ME, Rubio Rivera S. H.A.L.T. Healthy Alternative Lice Treatment Study, final clinical report. December 3, 2020. https://doi.org/10.5281/zenodo.23510395
- Cartwheel (FreezeNit, Inc.). Clinical Summary: HALT Study of the Nit Happens Complete Lice Treatment Kit, version 2. October 2026. https://doi.org/10.5281/zenodo.23510395
- Nit Happens Instructions for Use. https://gocartwheel.com/pages/nit-happens-instructions-for-use