The benefits of coconut oil for hair.

The benefit of coconut oil for dry and damaged hair largely rests on its capacity to interact with the hair fibre. Several studies have shown that, unlike many vegetable oils, the coconut oil is capable of partially penetrating into the hair shaft. This specificity is attributed to its richness in lauric acid, a medium-chain fatty acid whose linear structure and low molecular weight facilitate its diffusion between the cells of the cuticle and cortex. This affinity for hair proteins, notably keratin, explains why coconut oil is often associated with better preservation of the integrity of the fibre, particularly in weakened hair.

It should, however, be emphasised that, like all oils, coconut oil does not hydrate the hair in the strict sense, as hydration requires the presence of water.

Its primary role is lipidic: it helps to nourish the fibre and to limit the loss of proteins and lipids, a phenomenon frequently observed in dry, chemically treated or damaged hair. Indeed, by partially penetrating the hair shaft, coconut oil helps to fill in cracks in the cuticle, thereby improving its ability to reflect light, which can make hair appear shinier. When applied to the lengths, it also forms a surface protective film, which shields the fibre from external aggressors such as friction, pollution or UV rays. This coating effect can temporarily enhance the hair’s appearance.

Coconut oil is sometimes credited with the ability to act against dandruff, a common scalp disorder often associated with excessive scaling, itching and an imbalance of the cutaneous microbiome. While this use is partly based on traditional practices, some recent scientific data indeed suggest that coconut oil may be of interest in maintaining scalp balance, without, however, constituting a dandruff treatment in the strict sense.

A study specifically investigated the effect of a topical application of coconut oil on the scalp microbiome, both bacterial and fungal. This study, conducted on 140 women, 70 of whom had dandruff, ran for 16 weeks, including 12 weeks of treatment followed by a 4-week follow-up phase without application. The objective was to evaluate the impact of coconut oil on the microbial composition of the scalp and on certain physiological parameters associated with dandruff.

At the end of the treatment phase, the researchers observed an increase in certain microbial populations, notablyCutibacterium acnesandMalassezia globosa, whose abundance was negatively correlated with the clinical parameters of dandruff.

These findings suggest that coconut oil may help to modulate the microbial ecosystem of the scalp, but the precise mechanisms remain to be elucidated. Furthermore, coconut oil should not be a substitute for treatment in cases of dandruff persistent or severe. It could, however, be considered as an adjunct in a hair care routine.

Coconut oil is among the traditional natural remedies commonly recommended in cases of pediculosis, the scientific term for an infestation by lice. It is often thought to act by occlusion, the idea being that the oil coating the louse and its eggs suffocates them.

However, the available clinical data are considerably more reserved regarding the efficacy of coconut oil when used alone against head lice.

A clinical trial involving 31 participants evaluated a shampoo containing 1% fractionated coconut oil, administered twice at one-week intervals. The product’s efficacy was assessed by systematic combing at various stages of follow-up, but the results proved inconclusive. Lice at different developmental stages, along with nits, were detected throughout the monitoring period. These findings indicate a low pediculicidal and ovicidal activity, suggesting that coconut oil, even when modified and formulated into a shampoo, fails to eliminate lice effectively.

Conversely, some studies suggest that coconut oil may be of interest against head lice when it is combined with other plant extracts. One study in vitro thus investigated the ovicidal efficacy of formulations combining an extract of Illicium verum (star anise) and coconut oil. Lice eggs were immersed for short durations in various solutions, then incubated to assess their viability.

The most effective combination (60% star anise and 40% coconut oil) resulted in a nit mortality rate of 86.7% after two minutes of exposure.

Overall, these data indicate that coconut oil alone cannot be regarded as an effective treatment against lice. While certain combinations with other natural extracts appear promising, they require precise formulations and cannot be extrapolated to domestic uses or to the application of pure coconut oil on the scalp. In practice, the management of pediculosis relies on products whose efficacy has been demonstrated, combined with thorough combing.

To date, no scientific data demonstrates that coconut oil stimulates hair growth.

Conversely, coconut oil can contribute to improving the condition of the hair fibre and the scalp. By reducing breakage in weakened hair, it can help to preserve the length attained. Hair can then appear longer over time, not because of accelerated growth, but thanks to better length retention associated with decreased breakage.

Coconut oil exhibits a naturally greasy and occlusive texture, which necessitates some caution in its application, particularly on fine hair or scalps prone to greasiness. Today, numerous coconut oil shampoos are available, as well as conditioners and hair masks containing this ingredient, all of which enable the benefits of coconut oil to be harnessed. Outside of these products, it is also possible to add a few drops of coconut oil to an existing hair-care formulation, in order to benefit from its lipid properties while limiting the very greasy feel associated with the application of pure oil.

Coconut oil can also be used in the form of an oil bath, provided that the quantities remain moderate. A single targeted application—for instance once a week—to the hair lengths and, if necessary, to the scalp when very dry may be sufficient. A few drops are spread over the relevant areas and then left to act for about fifteen minutes before washing the hair.

Note : Coconut oil solidifies below 20–25 °C, but this has no impact on its quality. If this occurs, simply hold the jar under warm water until it liquefies again.

• BURGESS N. A. & 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).

• 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).

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

• KAMATH Y. & al. Benefit of coconut-based hair oil via hair porosity quantification. International Journal of Cosmetic Science (2022).

• AHN C. & al. Determination of penetration and protection of fatty acids in bleached hair according to the fatty acid chain length and the application to understanding the protective effects of MCT oil and coconut oil. Fashion and Textiles (2023).

• GAVA MAZZOLA P. & al. Impact of hair damage on the penetration profile of coconut, avocado, and argan oils into caucasian hair fibers. Cosmetics (2024).