What kills lice nits? - briefly
Chemical agents such as permethrin, pyrethrins, malathion, or dimethicone, and heat treatment at ≈ 130 °F (54 °C) for ≈ 10 minutes, destroy lice eggs. Using a fine‑toothed nit comb after treatment removes any surviving nits and prevents reinfestation.
What kills lice nits? - in detail
Lice eggs, commonly called nits, adhere tightly to hair shafts and survive many topical treatments that kill adult insects. Successful eradication requires agents that either dissolve the protective shell or disrupt the developing embryo.
Effective chemical agents:
- Permethrin 1 % lotion: neurotoxic insecticide that penetrates the nit membrane, causing paralysis of the embryo.
- Pyrethrins combined with piperonyl‑butoxide: synergistic formulation that enhances penetration and reduces resistance.
- Malathion 0.5 % shampoo: organophosphate that inhibits acetylcholinesterase, lethal to both nymphs and eggs.
- Benzyl alcohol 5 % spray: desiccates the nit, leading to embryo death within 10 minutes.
- Ivermectin 0.5 % lotion: binds to glutamate‑gated chloride channels, impairing embryonic development.
- Spinosad 0.9 % mousse: bacterial‑derived toxin that interferes with neural transmission, effective against resistant strains.
Physical removal techniques:
- Fine‑tooth nit comb (0.2 mm spacing) used on wet, conditioned hair; repeated passes eliminate up to 95 % of visible nits.
- Steam application at ≥ 100 °C for 10 seconds; heat denatures proteins within the egg shell.
- Hot air dryer set to high temperature for 15 minutes; sustained heat kills embryos without chemical exposure.
- Freezing at ≤ ‑20 °C for 30 minutes; low temperature halts metabolic activity and destroys the egg.
Environmental control measures:
- Machine wash clothing, bedding, and towels in water ≥ 60 °C; follow with tumble drying on high heat for at least 20 minutes.
- Seal non‑washable items in airtight plastic bags for a minimum of two weeks; absence of a host prevents hatching.
- Vacuum carpets, upholstered furniture, and car seats; discard vacuum bag or clean canister afterward.
Safety considerations:
- Permethrin and pyrethrins contraindicated for children under two months; follow label age restrictions.
- Malathion may cause skin irritation; use protective gloves and avoid inhalation.
- Benzyl alcohol unsuitable for infants younger than six months; monitor for allergic reactions.
- Repeated use of the same chemical class can promote resistance; rotate agents when feasible.
Combining chemical treatment with thorough combing and appropriate environmental steps yields the highest success rate in eliminating lice eggs.