With what agents are lice killed? - briefly
Lice are eliminated using chemical pediculicides (e.g., permethrin, pyrethrins, malathion, ivermectin) or physical agents such as silicone‑based dimethicone that suffocate the insects. Both categories act by disrupting the parasite’s nervous system or blocking its respiratory pathways.
With what agents are lice killed? - in detail
Lice infestations are eliminated by agents that either kill the insects directly or disrupt their life cycle. The most effective options fall into three categories: chemical pediculicides, physical treatments, and mechanical removal combined with supplemental substances.
Chemical pediculicides act as neurotoxins or physical coaters. Commonly used compounds include:
- Permethrin (1 %) – synthetic pyrethroid that interferes with nerve function; applied as a lotion or shampoo.
- Pyrethrins – natural extract from chrysanthemum flowers, often combined with piperonyl butoxide to enhance potency.
- Malathion (0.5 %) – organophosphate that inhibits cholinesterase; reserved for resistant cases due to toxicity concerns.
- Spinosad (0.9 %) – derived from bacterial fermentation; blocks nicotinic acetylcholine receptors.
- Ivermectin (0.5 %) – macrocyclic lactone that binds to glutamate‑gated chloride channels; available as a topical lotion or oral formulation for severe infestations.
- Benzyl alcohol (5 %) – suffocates lice by blocking spiracles; safe for children over six months.
- Dimethicone (4 %) – silicone polymer that coats and immobilizes lice, preventing breathing and attachment.
Physical treatments eradicate lice without chemicals. Heat‑based methods involve applying devices that raise scalp temperature to 50 °C for at least ten minutes, a level lethal to both adults and nymphs. Freezing treatments use specialized cold‑air systems that drop temperature below –20 °C for a comparable duration. Silicone‑based lotions or oils (e.g., dimethicone‑rich formulations) create a physical barrier that suffocates insects and facilitates removal.
Mechanical removal consists of wet combing with a fine‑toothed nit comb. When combined with a detangling solution such as a dilute vinegar or a non‑ionic surfactant, the process extracts live lice and viable eggs. Repetition every three to four days for at least two weeks ensures eradication of newly hatched nymphs.
Supplementary natural agents—tea tree oil, neem oil, eucalyptus oil—exhibit limited ovicidal activity. Their efficacy varies, and they are best employed as adjuncts rather than primary treatments.
Effective control requires adherence to product‑specific instructions: thorough application to dry hair, coverage of the entire scalp, and a mandatory second treatment 7–10 days after the first dose to target hatching eggs. Safety considerations include age restrictions, potential skin irritation, and contraindications for pregnant or lactating individuals. Resistance monitoring is essential; when treatment failure occurs, switching to a different chemical class or employing a physical method reduces the likelihood of persistent infestation.