How to kill a head louse? - briefly
Apply an FDA‑approved pediculicide (e.g., 1 % permethrin) to the scalp, follow the label‑specified exposure time, rinse, and repeat the treatment after 7–10 days; additionally, comb wet hair with a fine‑toothed nit comb to mechanically eliminate any remaining lice and eggs.
How to kill a head louse? - in detail
Head lice are obligate ectoparasites that attach to human hair shafts, feed on blood, and reproduce rapidly. An effective eradication program must combine direct treatment of the insects with measures that prevent re‑infestation.
Detecting an infestation involves inspecting the scalp for live insects and viable eggs (nits) within 1 cm of the hairline. Use a fine‑toothed comb on wet hair; move the comb slowly from root to tip, wiping the teeth after each pass. Presence of several live lice confirms the need for immediate intervention.
Treatment modalities
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Synthetic pediculicides – products containing permethrin (1 %), pyrethrins with piperonyl‑butoxide, or malathion (0.5 %). Apply to dry hair, leave for the manufacturer‑specified duration, then rinse. Repeat after 7–10 days to target newly hatched nymphs. Resistance to permethrin is documented; consider alternative actives if prior attempts failed.
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Spinosad – a bacterial‑derived insecticide effective against resistant strains. Use as a single application; follow with a second treatment only if live lice persist.
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Ivermectin lotion – 0.5 % formulation, applied to dry hair for 10 minutes before washing. Suitable for children over 6 months and adults.
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Benzyl alcohol lotion – works by asphyxiating lice; requires a 10‑day regimen with daily applications.
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Mechanical removal – wet‑combing with a metal nit comb at 2‑minute intervals for 10 days. Removes live insects and most nits without chemicals.
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Heat treatment – devices that heat hair to 50 °C for several minutes kill lice and eggs. Ensure device complies with safety standards to avoid scalp burns.
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Suffocation agents – silicone‑based oils (e.g., dimethicone) coat insects, blocking respiration. Apply to dry hair, leave for 15 minutes, then comb and wash.
Environmental control reduces the risk of re‑infestation. Wash clothing, bedding, and towels used within the previous 48 hours in water ≥ 60 °C or seal in plastic bags for two weeks. Vacuum carpets and upholstered furniture; avoid sharing combs, hats, or headphones.
A follow‑up inspection 7 days after the initial treatment confirms success. If live lice are observed, repeat the chosen method or switch to an alternative class of pediculicide. Continuous monitoring for two weeks prevents resurgence.