Which Is More Effective for Hair Growth?

If you’re trying to grow your hair, castor oil and rosemary oil are natural hair remedies that offer moisturizing, anti-inflammatory, and anti-fungal properties. Rosemary oil is more likely to promote hair growth from the hair follicle, while castor oil helps hydrate and strengthen hair to support healthy growth.

Castor oil and rosemary oil are both touted as natural hair growth remedies. However, research supporting these claims is limited.

Rosemary oil is more likely to help improve hair growth because it increases blood flow to the scalp and nourishes hair follicles. This is the same way hair growth medications like Rogaine (minoxidil) work to stimulate hair growth.

In a 6-month study including men with male-pattern hair loss, rosemary oil treatments were just as effective as minoxidil 2%. However, higher doses of minoxidil 5% were not tested.

There is no clear evidence that castor oil helps hair grow. Castor oil mainly helps moisturize the hair and scalp, which may support healthy hair growth.

Rosemary oil is an essential oil made from the rosemary plant (Rosmarinus officinalis L.) with various healing properties.

Potential benefits rosemary oil has on hair growth include:

• Stimulates and regenerates hair follicles: Rosmarinic acid, found in rosemary oil, helps increase blood flow to the scalp. This helps nourish and stimulate hair follicles, promoting healthy hair growth. Improving blood flow may also help regenerate hair follicles in people with male-pattern hair loss.
• Blocks androgens: Rosemary oil contains 12-methoxycarnosic acid, which may help block androgens that cause male- and female-pattern hair loss. High levels of androgens can shrink hair follicles, shorten the growth phase, and increase the shedding phase.
• Reduces and relieves fungal infections: Rosemary oil has antifungal properties that may help reduce fungal growth linked to dandruff and scalp infections. Anti-inflammatory properties may also help soothe irritation, itching, and dryness that can affect scalp health and hair growth.

Castor oil is a thick oil made from the seeds of the castor oil plant (Ricinus communis). When ingested, castor oil acts like a laxative and promotes bowel movements. Castor oil is also used as a moisturizer when applied to the skin or hair.

Potential benefits of castor oil for hair growth include:

• Moisturizes hair follicles: Castor oil contains numerous fatty acids—most notably ricinoleic acid—that help the hair and scalp lock in moisture. By coating the hair and sealing in your natural oils, castor oil also helps improve shine and protects your hair from breakage.
• Prevents scalp infections: Ricin and ricinoleic acid in castor oil have antimicrobial properties that may help prevent bacterial and fungal scalp infections, which can contribute to hair loss. 
• Soothes irritation: Castor oil’s ricinoleic acid appears to help reduce inflammation and repair a damaged skin barrier. This effect may help soothe and heal an irritated scalp.
• Blocks hair loss-related enzymes: Limited research shows that the linoleic acid in cator oil may inhibit prostaglandin D2 synthase (PGD2). This enzyme can slow or stop hair growth. People with androgenetic alopecia, aka male- or female-pattern hair loss, have high levels of PGD2 on their scalp.

Rosemary oil is highly concentrated and can irritate your scalp if used alone. Try adding a few drops of rosemary oil to argan, coconut, or jojoba oil, and focus on massaging the mixture into your scalp. Let the treatment sit for about 5–10 minutes before rinsing. You can also add rosemary oil to shampoo and wash as usual. 

Castor oil is very thick and sticky, and should also be mixed with a few drops of castor oil with a carrier oil like coconut oil, jojoba oil, or argan oil. Then, massage the oil mixture into your scalp and work it into your hair. Let it sit for 5–10 minutes before shampooing.

If you have fine hair, using castor oil more than once a week may cause buildup and tangles. Hair types that need more moisture, like curly or coily hair, can use castor oil 2–3 days a week.

You can also mix castor oil, rosemary oil, and a carrier oil together to get the most of both oils’ benefits. However, if you’re experiencing hair loss, talk with your healthcare provider before using castor oil or rosemary oil. You may have an underlying health condition that requires a different treatment.

Rosemary and castor oils are generally safe, but both products can irritate the skin and cause allergic reactions. Allergic reactions to castor oil are more likely if you’re allergic to the castor bean plant.

Highly concentrated rosemary oil is more likely to irritate your skin and should be diluted with a carrier oil or a hair product. Always do a patch test to see how your skin reacts before applying a new product to your scalp. 

Signs you may be experiencing an allergic skin reaction to rosemary or castor oil include: 

• Redness
• Burning
• Itching
• Open sores

Castor oil can also cause the hair to tangle into a stiff, impossible-to-separate clump. This is called acute hair felting and can lead to unwanted haircuts.