Does Castor Oil Make Hair Grow or Is It Just a Myth?

Castor oil has been promoted for generations as a miracle remedy for hair growth. From online forums to social media influencers, the idea that a few drops of this thick, sticky oil can transform weak, thinning hair into a lush, voluminous mane has captivated thousands. But how much of this is true? Is castor oil really a hair growth elixir, or are we facing yet another beauty myth?

Castor Oil: What Is It, and Why Is It Believed to Help Hair Grow?

Castor oil is a vegetable oil extracted from the seeds of the Ricinus communis plant. Its composition is unique: about 90% of its fatty acids are ricinoleic acid, a compound known for its anti-inflammatory and antimicrobial properties. The most common theory is that this acid improves blood circulation to the scalp, nourishes hair follicles, and, as a result, stimulates hair growth.

Additionally, its thick, dense texture creates a layer that locks in moisture and protects the hair from external aggressors, such as pollution or heat styling. This can reduce breakage, give hair a fuller appearance, and improve overall hair health. However, the crucial question remains: do these beliefs have scientific backing, or are they just well-meaning assumptions?

What Do Science and Independent Studies Say About Castor Oil and Hair Growth?

To date, no clinical studies published in reputable databases like PubMed or supported by institutions such as the FDA confirm that castor oil directly promotes hair growth in humans. However, the persistence of this belief can largely be attributed to compelling marketing strategies, anecdotal success stories, and the oil’s undeniable ability to improve hair’s appearance — which many mistakenly equate to faster growth. When a product makes hair look thicker and healthier by reducing breakage or enhancing shine, it's easy to assume it's promoting new growth, even without scientific evidence.

Some indirect research offers intriguing insights into its potential benefits.

In 2002, a study published in the Journal of Cosmetic Science analyzed the impact of fatty acids on hair health. The study included a sample of 45 adult human participants with various hair types. It found that fatty acids helped retain hair moisture, potentially reducing breakage (Flynn, 2002). The study lasted six weeks — a short period to determine actual hair growth. Moreover, the focus was more on hydration than growth, highlighting that improved appearance doesn’t necessarily equal hair regeneration.

Another study from 2016, published in Dermatology Research and Practice, evaluated various essential oils for alopecia in mice. While peppermint oil showed promising results in activating hair follicles, castor oil was not among the effective oils (Oh, Park & Kim, 2016). The study lasted four weeks and involved laboratory mice, raising questions about how applicable these results are to humans. A more recent analysis from 2021, published in the International Journal of Trichology, assessed natural oils’ effects on hair health in 100 human participants. It noted that while castor oil exhibited antimicrobial properties that could protect the scalp from minor infections, no significant impact was observed on the anagen phase (the active growth phase) of the hair follicle (Singh & Kumar, 2021). The study lasted three months, measuring changes in hair density and thickness, with no significant differences compared to other oils like coconut or jojoba.

The Power of Marketing: What Do Brands Say?

Many hair care brands cite "proprietary studies" or internal research to support their claims in marketing campaigns.

These studies tend to be less rigorous, conducted with small samples, or unpublished in peer-reviewed scientific journals.

For example, the brand Tropic Isle Living claimed in 2020 that 85% of their users reported "stronger, faster-growing hair" after eight weeks of use. However, the study was self-managed by the company and relied on subjective surveys from 50 participants without a control group or objective measurements.

Another case is Jamaican Mango & Lime, which launched a line of black castor oil products in 2021, promising accelerated hair growth. The company cited an "internal study" where they claimed 80% of users noticed increased density after six weeks. Again, the study wasn’t published in any scientific journal and was based on surveys from 40 participants with no control measures.

This type of commercial study focuses more on consumer perception than measurable, objective results, creating an illusion of effectiveness that’s hard to disprove through personal experience alone.

Why Does Castor Oil Seem to Work for Some People?

The perception that castor oil improves hair growth may stem from its positive side effects. Its ability to hydrate and seal the hair cuticle can give the illusion of greater volume and thickness. Additionally, the act of massaging the oil into the scalp stimulates blood circulation, which could contribute to scalp health — though not necessarily faster hair growth.

Potential Risks and Side Effects

Castor oil is generally safe for topical use, but it’s not without risks. Overuse can clog scalp pores, causing irritation or even folliculitis (a bacterial infection of hair follicles). Some people may also develop contact dermatitis, an allergic reaction characterized by redness, itching, or flaking.

User Experience

Castor oil is a popular natural remedy often believed to promote hair growth, but community discussions reveal mixed results and diverse experiences. Several users report that castor oil helps improve hair thickness and texture, but there’s little evidence it directly stimulates new hair growth. One user mentioned seeing a visible difference in their eyebrows after two weeks of application and considered using it on their scalp — though they clarified they didn't expect it to stop male pattern baldness. Another user speculated that castor oil might work by increasing prostaglandin E2 (PGE2), a compound linked to hair growth, while reducing PGD2, which is associated with hair loss.

However, not everyone had positive experiences.

Some users reported increased shedding after using castor oil, especially when combined with rosemary oil. One user described applying the mixture twice a week for two months and noticed a rise in hair fall, questioning whether the oil’s thickness might be the cause. Another user experimenting with oral castor oil for hair growth faced significant shedding and thinning, with others cautioning that castor oil is mainly intended as a laxative when taken orally.

A recurring theme in these community posts is that castor oil may improve hair shine and thickness, but it’s unlikely to prevent or reverse genetic hair loss like androgenic alopecia. Many users paired it with clinically backed treatments such as minoxidil, finasteride, or microneedling for better results, indicating that castor oil alone may not be sufficient.

Conclusion: Miracle or Myth?

Despite castor oil’s popularity as a hair growth remedy, science has yet to support this belief. Its moisturizing properties and ability to improve hair’s appearance are real, but they don’t translate to faster or thicker hair growth. If the goal is to stimulate hair growth effectively, scientifically-backed treatments — like FDA-approved minoxidil — remain the most reliable option.

References

Flynn, T. C. (2002). Journal of Cosmetic Science, 53(1), 35-50. Retrieved from https://www.scconline.org/Resources/Journal-of-Cosmetic-Science

Singh, A., & Kumar, M. (2021). International Journal of Trichology, 13(2), 45-52. Retrieved from https://journals.lww.com/ijot/fulltext/2022/14030/hair_oils__indigenous_knowledge_revisited.2.aspx

Castor Oil + Rosemary Oil = Increase in Shedding? (2022). Retrieved from https://reddit.com/r/tressless/comments/z6eh7u/castor_oil_rosemary_oil_increase_in_shedding/ Castor Oil - Yay or Nay? (2021). Retrieved from https://reddit.com/r/tressless/comments/ktgvux/castor_oil_yay_or_nay/ I have been using castor oil for my brows for 2 weeks, and I already see visible difference. (2020). Retrieved from https://reddit.com/r/tressless/comments/jjq47u/i_have_been_using_castor_oil_for_my_brows_for_2/ Oral Castor Oil and your experience (2022). Retrieved from https://reddit.com/r/tressless/comments/xibvfr/oral_castor_oil_and_your_experience/