Pediculicide Resistance and Current Therapeutic Effectiveness in Pediculus Humanus Capitis: A Literature Review

Pediculus humanus capitis infestation remains a persistent global public health burden, with recent evidence showing a sharp decline in treatment success due to widespread pediculicide resistance. Over the past decade, molecular studies have consistently identified a high frequency of voltage-gated sodium channel (kdr) mutations—particularly T917I, L920F, T929I, and L932F—which significantly reduce lice sensitivity to pyrethroid-based agents such as permethrin and fenothrin. These mutations are often accompanied by increased activity of detoxification enzymes, including acetylcholinesterase, glutathione S-transferase, and cytochrome P450 oxidase, which contribute to cross-resistance and explain repeated treatment failures in communities. Clinical and laboratory bioassays conducted between 2020 and 2025 in Indonesia, Thailand, Iran, India, Saudi Arabia, Turkey, and several African regions consistently reported low mortality and longer survival after pyrethroid exposure, confirming that resistance is now globally entrenched. In contrast, emerging non-pyrethroid therapies such as dimethicone formulations, 0.5% topical ivermectin, squalane-based preparations, and standardized botanical shampoos demonstrate strong and sustained pediculicidal activity with minimal evidence of resistance, reduced reinfestation, and a good safety profile. These alternatives primarily work through physical mechanisms or neuro-inhibitory pathways unaffected by kdr mutations, making them promising first-line options. This literature review synthesizes findings from 10–12 primary studies supported by 26 recent publications to provide an up-to-date overview of resistance mechanisms, kdr mutation distribution, and the comparative effectiveness of existing therapies. Overall, the available evidence highlights the need to revise treatment guidelines, enhance molecular surveillance, and prioritize non-pyrethroid agents.