What kills lice on the head? - briefly
Pediculicidal treatments—including 1 % permethrin shampoo, pyrethrin‑piperonyl‑butoxide lotion, or dimethicone‑based products—kill live lice, while a fine‑toothed nit comb removes remaining eggs.
What kills lice on the head? - in detail
Effective eradication of scalp lice requires agents that either kill the insects directly or disrupt their life cycle. Chemical pediculicides, such as permethrin (1 %) and pyrethrin, act on the nervous system of the parasite, causing rapid paralysis and death. Dimethicone, a silicone‑based oil, suffocates lice by coating their respiratory openings. Malathion (0.5 %) and spinosad (0.9 %) provide alternative mechanisms for resistant populations, interfering with enzyme activity essential for survival.
Physical methods complement chemical treatments. Wet combing with a fine‑toothed lice comb removes live insects and nits when performed on damp hair for 10 minutes per session, repeated every 2–3 days for two weeks. Heat therapy, using a device that raises scalp temperature to 50 °C for several minutes, destroys lice without chemicals. Freezing sprays containing dimethyl ether cause instant lethal exposure.
Home‑based substances lack reliable efficacy but are sometimes used adjunctively. High‑concentration alcohol (≥ 70 %) denatures proteins and can kill lice on contact, yet it does not penetrate egg shells. Essential oils (tea tree, neem) exhibit insecticidal properties in laboratory studies; however, clinical data are limited, and skin irritation is possible.
Key considerations for safe application:
- Verify product concentration and expiration date before use.
- Follow manufacturer instructions regarding dosage, exposure time, and repeat treatment schedule.
- Avoid application on broken skin, infants under 2 months, or individuals with known hypersensitivity.
- After chemical treatment, wash all clothing, bedding, and personal items in hot water (≥ 60 °C) or seal them in a plastic bag for two weeks to prevent re‑infestation.
- Conduct a post‑treatment inspection with a lice comb to confirm elimination; repeat combing for at least seven days.
Resistance monitoring is essential. Populations showing reduced susceptibility to permethrin or pyrethrin should be managed with alternative agents such as dimethicone or spinosad, combined with thorough mechanical removal. Proper adherence to treatment protocols and environmental decontamination yields the highest success rate in eliminating head lice.