Hair, eyelashes, eyebrows, and beard: what benefits does castor oil have on hair follicles?

Castor oil can also protect the scalp, hair, eyelashes, eyebrows, and beard hair from oxidation. While the effects of oxidative stress on skin are documented, its impact on scalp and body hair remains overlooked. The buildup of free radicals in hair follicles is significant and can accelerate hair shedding and graying. Free radicals generated by UV rays, pollution, or tobacco smoke oxidize cuticle lipids and keratin amino acids. This lipid peroxidation reduces cuticle cohesion and increases the porosity and fiber fragility.

Rich in tocopherols and phenolic compounds, castor oil traps free radicals before they damage hair follicles and the hair fiber. This slows the aging of the hair fiber and maintains its radiance. A 2021 study examined the antioxidant properties of castor oil. Researchers performed the DPPH assay based on the reduction of the DPPH2 This assay measures the antioxidant activity of a compound. The median inhibitory concentration (IC50) was determined. It is the concentration needed to inhibit 50% of a chemical reaction. In this specific case, the IC50 reflects the antioxidant efficacy of castor oil. An IC50 of 431.73 μg/mL was measured. This value is low, indicating that a small amount of castor oil provides effective antioxidant activity.

Regular application of castor oil to hair, lashes, eyebrows, and beard can be part of a strategy of photoprotection.

Note: To date, no scientific study has shown that castor oil slows down the appearance of white hair or grey hair. However, it has been established that this oil possesses antioxidant properties, which is interesting since oxidative stress is recognized as a factor accelerating hair bleaching. Despite this, no direct evidence confirms that the application of castor oil influences the appearance of gray hair.

The castor oil is sometimes cited as a natural remedy for dandruff. Dandruff occurs when cell turnover is too rapid. If epidermal cells have not matured sufficiently, they remain clumped together and detach as white clusters, forming dandruff. The causes of dandruff are numerous and remain poorly understood, but studies suggest a link between them and the fungal proliferation of the Malassezia.

To date, no clinical study has shown castor oil to act against dandruff. Some studies have highlighted its antifungal properties and shown that the undecylenic acid in this oil acts against certain pathogens and yeasts, including Staphylococcus aureus and Klebsiella pneumoniae. No research has examined castor oil’s effect on Malassezia fungi that promote dandruff. Even though it cannot be stated that castor oil eliminates dandruff, it appears to have a certain cleansing activity, useful for caring for the scalp and beard.

If castor oil is good for all types of hair (fine hair, curly hair, frizzy hair...), its rich texture makes it particularly suitable for frizzy hair, often lacking hydration.

Castor oil can be used in various ways to care for your hair and suit your needs. If your priority is to stimulate growth, warm a few drops of castor oil between your hands, then massage your scalp using circular motions to promote absorption. Avoid applying too much: castor oil is quite viscous and may weigh down the scalp. Leave on for 30 minutes to overnight, then rinse with your regular shampoo. Note that you may need to shampoo twice to fully remove the oil. To nourish your mid-lengths, protect your hair from environmental stressors, or restore shine, apply a few drops to lengths and ends. If you leave it on overnight, consider a protective hairstyle such as a braid or a loose bun: this prevents tangles, protects your pillow, and keeps the oil in place.

One to two applications per week suffice to provide castor oil’s benefits without weighing down your hair.

Beard application follows the same principle, but we advise those with oily skin to be cautious. Even if the castor oil is not considered comedogenic, it can leave an unpleasant greasy residue when skin already produces excess sebum. In that case, leave the oil on for about thirty minutes in the evening before cleansing your face with your cleansing gel or your regular cleansing cream. For lashes and brows, the application must be precise to avoid excess build-up. Castor oil can be applied using a small fine brush or a clean spoolie, such as an empty mascara wand, at the base of the lashes or brows.

Note: It is sometimes said that using castor oil in the eyelashes is dangerous. One must indeed be cautious and remain parsimonious when applying it because its ocular toxicity is still poorly known. Using unsterilised castor oil near the eyes may lead to irritation or infection. That is why, to prevent this risk, it is recommended to apply it in small quantities, using a clean bottle brush reserved for this use.