Is coconut oil effective at killing head lice?

Whereas conventional lice treatments use neurotoxic agents to which the parasites are becoming increasingly resistant, coconut oil appears to act through a mechanical suffocation mechanism.

Due to its occlusive effects, this vegetable oil forms a thick hydrophobic film that is likely able to coat the entire louse. This may obstruct the spiracles, the tiny respiratory openings located along the abdomen of the parasite. Deprived of oxygen, the louse dies from suffocation, a purely physical mechanism against which it cannot develop biological resistance.

Beyond this lethal action, the lipid structure of coconut oil would alter the scalp environment to facilitate the removal of parasites. Its lubricating texture would markedly reduce the ability of lice to adhere to the hair shaft, preventing them from attaching firmly. This “slip effect” would also enable the comb to capture adults and nymphs more easily, while helping to detach the chitinous sheath of the nits, those eggs often cemented to the hair with a highly resistant biological glue.

Finally, a biochemical hypothesis completes this picture. Coconut oil is very rich in lauric acid, a medium-chain fatty acid whose antimicrobial properties are well documented. In the context of an antiparasitic treatment, it is assumed that this fatty acid could interact with the waxy cuticle that protects the louse’s exoskeleton. By altering this protective barrier, coconut oil could weaken the parasite, making it more susceptible to asphyxiation.

However, although these theoretical mechanisms are promising, their actual effectiveness in real-world conditions remains the subject of debate within the scientific community.

To validate these theoretical hypotheses, several research teams have tested coconut oil under real-world conditions. An initial clinical study conducted in Israel examined the effectiveness of a natural remedy composed of a mixture of coconut oil, anise oil and ylang-ylang oil. In a context where around 20% of children aged 4 to 13 were infested, often due to head lice developing resistance to conventional products, the researchers compared this mixture with a standard insecticidal spray containing permethrin and malathion. The protocol involved three applications of fifteen minutes each, spaced five days apart. The results were particularly convincing.

This study suggests that coconut oil, particularly when combined with other oils, may represent a valid alternative to conventional treatments.

While acting on adult lice is essential, one of the greatest challenges remains the removal of nits in order to prevent a new cycle of infestation. A second line of research has therefore focused on the ovicidal potential, that is, the ability to kill the eggs, of coconut oil when combined with other plant-derived actives. An in vitro study specifically tested the effectiveness of formulations combining an extract of star anise (Illicium verum) and coconut oil. The protocol involved immersing louse eggs in different solutions for very short periods before incubating them to observe whether they were able to hatch. The results highlighted a strong synergy.

The optimal mixture, consisting of 60% star anise and 40% coconut oil, caused the death of 86.7% of the nits after only two minutes of exposure.

These data suggest that coconut oil, in addition to its occlusive role, can serve as a carrier to maximise the penetration of natural insecticidal active agents through the protective wall of the egg, making the overall treatment markedly more effective.

That said, more recent studies have produced less promising results. A 2020 study involving 31 people assessed the impact of a shampoo containing 1% fractionated coconut oil, applied twice, one week apart. In contrast to highly concentrated oil blends, this product showed mixed results. Lice at different stages of development, as well as viable nits, were found in participants throughout the follow-up period.

These data indicate a low pediculicidal and ovicidal activity in this configuration, suggesting that coconut oil, when it is too diluted or incorporated into a conventional cleansing base, loses its occlusive power that enables it to eliminate lice effectively.

To maximise the asphyxiating effect, coconut oil must be applied generously to the entire head of dry hair, paying particular attention to the roots and the nape of the neck. A prolonged application time, ideally between around thirty minutes and one hour, is necessary to ensure the blockage of the parasites’ respiratory openings. After this period, you can proceed with a shampoo, before using a fine nit comb. The lubricating texture of the oil will make it easier for the comb to glide and for the nits to be detached. Finally, since pure coconut oil does not have complete ovicidal efficacy, it is essential to repeat the procedure two to three times, at three-day intervals, to eliminate the nymphs that hatch from eggs that survived the first treatment.

• INGBER A. & al. The in vivo pediculicidal efficacy of a natural remedy. The Israel Medical Association Journal (2002).

• GRITSANAPAN W. & al. Anti-head lice effect of Annona squamosa seeds. The Southeast Asian Journal of Tropical Medicine and Public Health (2006).

• MARKS M. & al. Head lice: An under-recognized tropical problem. The American Journal of Tropical Medicine and Hygiene (2017).

• SUTEJO I. R. & al. In vitro ovicidal activity of combination Illicium verum extract and coconut oil against Pediculus humanus capitis. International Conference on Agromedicine and Tropical Diseases (2020).

• BURGESS N. & al. ‘‘Anti-lice protector shampoo’’: Clinical study shows lack of efficacy of coconut oil derivatives in the elimination of head louse infestation. Turkish Journal of Parasitology (2020).

• SHARMA V. K. & al. Longitudinal study of the scalp microbiome suggests coconut oil to enrich healthy scalp commensals. Scientific Reports (2021).