How and with what to kill lice? - briefly
Use a 1 % permethrin or pyrethrin shampoo, or a prescription option such as spinosad or oral ivermectin, then comb the hair thoroughly with a fine‑tooth lice comb after each wash; also launder bedding and clothing in water ≥130 °F and dry on high heat.
How and with what to kill lice? - in detail
Effective eradication of head‑lice infestations requires a systematic approach that combines appropriate chemical or physical agents with thorough environmental control.
The first step is accurate identification. Live lice are visible on the scalp, while nits cling tightly to hair shafts within 1 cm of the scalp. Removing all visible insects confirms the presence of an active infestation and guides treatment choice.
Chemical agents approved for human use include:
- Synthetic pyrethroids (e.g., 1 % permethrin lotion). Applied to dry hair, left for 10 minutes, then rinsed. Resistance is reported in some regions; confirm local susceptibility before use.
- Pyrethrins with piperonyl‑butoxide. Similar application protocol; the synergist counteracts metabolic resistance.
- Malathion 0.5 %. Oil‑based formulation, applied to dry hair, left for 8–12 hours, then washed out. Suitable for resistant strains but contraindicated for children under 6 months.
- Benzyl alcohol 5 % lotion. Non‑neurotoxic, kills lice by asphyxiation. Requires a 10‑minute exposure; repeat after 7 days to eliminate newly hatched nymphs.
- Ivermectin 0.5 % lotion. Single application, effective against resistant lice; may be repeated after 7 days if live lice persist.
Prescription‑only options, such as oral ivermectin (200 µg/kg) or spinosad 0.9 % lotion, are reserved for severe or refractory cases.
Physical and natural methods provide alternatives or adjuncts:
- Wet combing with a fine‑toothed lice comb. Hair is saturated with water and conditioner, then combed section by section for 10–15 minutes. Repeated every 2–3 days for two weeks removes both lice and nits.
- Dimethicone‑based products (silicone lotions). Coat the exoskeleton, causing dehydration and immobilization. Application similar to chemical pediculicides; no resistance reported.
- Essential‑oil mixtures (tea‑tree oil 1 %, neem oil 2 %). Applied to damp hair, left for 30 minutes, then rinsed. Evidence is limited; use as supplemental treatment.
- Heat treatment: Hair dryer set to high heat (≥ 130 °C) applied for 5 minutes after wet combing can kill lice but may damage hair; not recommended for routine use.
Environmental decontamination reduces reinfestation risk:
- Wash bedding, clothing, and towels used within the previous 48 hours in hot water (≥ 60 °C) and dry on high heat.
- Seal non‑washable items (e.g., stuffed toys) in a sealed plastic bag for two weeks.
- Vacuum carpets and upholstered furniture; discard vacuum bags after use.
Treatment protocol:
- Apply chosen pediculicide according to manufacturer instructions; ensure scalp coverage.
- Rinse after the specified exposure time; avoid immediate shampooing that could reduce efficacy.
- Perform a second application 7 days later to target eggs that hatched after the first treatment.
- Conduct wet combing daily for the first week, then every other day for the next week to verify eradication.
- Implement environmental cleaning concurrently.
Monitoring for side effects—skin irritation, itching, or allergic reactions—is essential. Discontinue the product and seek medical advice if severe reactions occur.
Combining a proven pediculicidal agent with meticulous combing and environmental hygiene offers the most reliable solution for eliminating head‑lice infestations.