Isopropyl myristate is used as a treatment for head lice based on scientific evidence supporting its efficacy. Rather than acting as a traditional insecticide, isopropyl myristate functions as a physical agent by dissolving the waxy exoskeleton of lice, which leads to dehydration and death of the parasites. Clinical studies have demonstrated its effectiveness: for example, randomized controlled trials have shown that formulations containing isopropyl myristate (typically 50% solution in a vehicle) can achieve cure rates comparable to or better than traditional neurotoxic lice treatments, such as permethrin or pyrethroids, particularly in cases where resistance to older treatments is common (Heukelbach et al., 2008; Burgess et al., 2009). Its mode of action also reduces the risk of resistance development, as it does not rely on neurotoxicity. Additionally, isopropyl myristate is generally well-tolerated, with a low incidence of adverse effects, mostly limited to minor scalp irritation.

Regulatory authorities in several countries have approved isopropyl myristate-based products for over-the-counter lice treatment. The evidence base includes both laboratory and clinical data, though the number of large-scale, high-quality studies is somewhat limited, resulting in a moderate (but not high) evidence rating. Overall, the use of isopropyl myristate for head lice is justified by scientific validation rather than tradition.