How often can lice be poisoned? - briefly
One application of a registered pediculicide typically kills all existing lice. A follow‑up dose 7–10 days later prevents survival of newly emerged insects.
How often can lice be poisoned? - in detail
Lice treatment relies on applying a pediculicide, allowing a short interval before re‑application. The first dose is applied to dry hair, left for the time specified on the product label, then rinsed. A second dose is recommended 7–10 days after the initial application to eliminate newly hatched nymphs that survived the first exposure. For products containing permethrin, malathion, or dimethicone, a third application is seldom needed, but some manufacturers advise an additional treatment 14 days after the first if heavy infestation persists.
Resistance patterns influence repeat schedules. In regions where head‑lice populations show reduced sensitivity to pyrethroids, guidelines suggest extending the interval to 10 days and adding a third dose 14 days after the initial treatment. For non‑neurotoxic agents such as silicone‑based lotions, a single application may suffice, but a follow‑up dose after 9 days remains common practice to ensure complete eradication.
Safety limits restrict the number of applications within a month. Most over‑the‑counter formulations advise no more than three treatments in a 30‑day period. Prescription‑strength products, such as spinosad, allow up to two applications within the same timeframe, provided a minimum of 7 days separates each use. Exceeding these limits increases the risk of skin irritation and systemic absorption.
Environmental control does not require chemical poisoning of lice on surfaces. Regular washing of bedding, clothing, and hats at 60 °C, followed by drying on high heat, eliminates residual insects. Vacuuming upholstered furniture and carpets reduces re‑infestation risk. These measures, combined with the treatment schedule above, keep the infestation cycle broken without excessive chemical exposure.