What do nits and lice fear? - briefly
Nits and lice are vulnerable to insecticidal shampoos, prescription treatments, and sustained high temperatures that kill them. They also cannot survive without a human host, so removal of the host or prolonged isolation leads to their demise.
What do nits and lice fear? - in detail
Nits and lice are vulnerable to specific environmental conditions and chemical agents that disrupt their life cycle.
Heat above 130 °F (54 °C) for at least five minutes denatures proteins and kills both eggs and adult insects. Direct sunlight, which raises surface temperature, also proves lethal when exposure exceeds 30 minutes.
Desiccation poses a serious threat. Low humidity (below 30 %) removes moisture from the exoskeleton, causing rapid dehydration. Air-drying hair with a high‑velocity dryer for several minutes achieves this effect without chemical residues.
Chemical treatments remain the most common control method.
- Permethrin (1 % lotion): interferes with neural transmission, paralyzing and killing insects within minutes.
- Pyrethrin‑based shampoos: act on sodium channels, leading to rapid immobilization.
- Dimethicone (silicone oil): coats eggs and insects, suffocating them by blocking spiracles.
Physical removal complements chemical action. Fine‑toothed combs, when used on wet hair with a conditioner, mechanically dislodge nits and lice. Repeated combing at 2‑day intervals eliminates newly hatched nits before they mature.
Biological agents offer an alternative. The fungus Beauveria bassiana infects lice, proliferating within the host and causing death within 48 hours.
Environmental sanitation reduces reinfestation risk. Washing clothing, bedding, and towels at 140 °F (60 °C) or sealing them in airtight bags for two weeks eliminates dormant stages.
In summary, extreme heat, low humidity, targeted insecticides, silicone oils, mechanical extraction, fungal pathogens, and rigorous laundering constitute the primary factors that effectively eradicate nits and lice.