How do lice treatments work? - briefly
Lice treatments employ either neurotoxic chemicals that bind to the insect’s sodium channels, causing paralysis, or physical agents that coat and suffocate the parasites. Silicone‑based lotions and dimethicone sprays create a barrier that blocks respiration, while synthetic pyrethroids disrupt nerve function, leading to rapid death of the lice.
How do lice treatments work? - in detail
Lice eradication relies on agents that interrupt the parasite’s life cycle or physically remove it from the host. Chemical pediculicides contain neurotoxic compounds such as permethrin, pyrethrins, or malathion. These substances bind to voltage‑gated sodium channels in the louse’s nervous system, causing prolonged depolarization, paralysis, and death. Resistance develops when mutations alter channel structure, reducing binding affinity; therefore, formulations may combine synergistic agents or rotate active ingredients to preserve efficacy.
Silicone‑based products, exemplified by dimethicone, act as physical occlusive agents. The low‑viscosity silicone penetrates the exoskeleton, coating respiratory spiracles and disrupting gas exchange. Simultaneously, the fluid spreads through the cuticle, leading to dehydration and immobilization without relying on neurotoxic mechanisms, which minimizes the risk of resistance.
Physical removal methods include fine‑tooth combs used on damp hair. The comb’s spacing (typically 0.2–0.25 mm) captures live lice and nits, allowing mechanical extraction. Repeated combing over several days eliminates newly hatched nymphs that escape initial treatment, as the life cycle from egg to adult spans approximately 7–10 days.
Oral medications, such as ivermectin tablets, provide systemic action. Ivermectin binds to glutamate‑gated chloride channels in the parasite, increasing membrane permeability, causing hyperpolarization, paralysis, and death. Oral therapy is reserved for severe infestations or cases where topical agents are contraindicated.
Effective application follows these steps:
- Apply the chosen product according to manufacturer instructions, ensuring complete coverage of hair and scalp.
- Maintain the required contact time (usually 10–15 minutes for neurotoxic agents, longer for silicone formulations).
- Rinse thoroughly, then repeat the treatment after 7–10 days to target any surviving eggs.
- Perform daily combing for 2 weeks to remove residual nits and prevent re‑infestation.
- Launder bedding, clothing, and personal items at ≥ 60 °C or seal in plastic bags for 2 weeks to eliminate environmental reservoirs.
Safety considerations include avoiding excessive exposure to neurotoxic agents on broken skin, restricting use in children under the recommended age, and observing contraindications such as pregnancy or known hypersensitivity. Monitoring for adverse reactions—skin irritation, redness, or systemic symptoms—ensures prompt medical evaluation.
Overall, lice control integrates chemical toxicity, physical suffocation, mechanical extraction, and systemic therapy, each targeting distinct physiological vulnerabilities of the parasite. Combining methods and adhering to scheduled re‑treatments maximizes eradication while mitigating resistance development.