How does a lice treatment work? - briefly
Lice treatments employ insecticidal agents that infiltrate the insect’s nervous system, causing rapid paralysis and death, while also loosening the adhesive that holds eggs to hair shafts. A follow‑up combing step mechanically removes the dead insects and any remaining nits.
How does a lice treatment work? - in detail
Lice eradication products act by targeting the nervous system of the parasite. Most over‑the‑counter preparations contain neurotoxic insecticides such as permethrin, pyrethrins, or dimethicone. These agents interfere with sodium channel function, causing rapid paralysis and death of adult lice and nymphs.
The treatment process typically follows these steps:
- Application – The medicated lotion, shampoo, or mousse is applied to dry hair, ensuring thorough coverage from scalp to tips. Dense application blocks the breathing tubes (spiracles) of the insects and distributes the active ingredient evenly.
- Absorption period – The product remains on the hair for a prescribed duration, usually 10–15 minutes. During this time the chemical penetrates the exoskeleton and reaches the central nervous system.
- Rinsing – After the exposure interval, the hair is rinsed with water. Residual compound may continue to act for a short period, killing any lice that were not immobilized initially.
- Nit combing – A fine‑toothed comb removes dead insects and viable nits that survived the chemical exposure. Repeating the combing over several days eliminates newly hatched lice before they mature.
- Second application – Many protocols advise a repeat dose 7–10 days later. This timing coincides with the life cycle of the egg, preventing emergence of any surviving nymphs.
Alternative treatments rely on physical mechanisms rather than chemicals. Dimethicone, a silicone‑based oil, coats the exoskeleton, suffocating the parasite by blocking gas exchange. Heat‑based methods raise scalp temperature to 50 °C for a few minutes, denaturing proteins and causing lethal dehydration. Both approaches avoid resistance issues associated with insecticide use.
Effectiveness depends on correct dosage, thorough coverage, and adherence to the repeat‑treatment schedule. Failure to treat nits or to perform the second application often results in reinfestation. Proper washing of bedding, clothing, and personal items reduces the risk of re‑colonization from environmental sources.