Does castor oil grow hair?
Short answer: no. There is no good clinical evidence that castor oil makes hair grow, and anyone telling you otherwise is selling harder than we are. Here is the long answer, including why we renamed a product line over it.
What the research actually says
Castor oil has been used on hair for a very long time, and length of tradition is not evidence. When health writers go looking for trials showing castor oil accelerates hair growth, they do not find them — the support is anecdotal, not clinical.
There is one piece of laboratory work people cite: a 2015 paper identifying ricinoleic acid, the fatty acid castor oil is mostly made of, as a possible inhibitor of prostaglandin D2, a molecule involved in some hair loss. That is a long way from a bottle of oil on a human scalp producing new hair. It is a reason to keep studying it, not a reason to buy it.
So why does everyone say it works?
Because something real does happen, and it is easy to misread. Castor oil is thick, and it coats. A 2003 study found castor oil increased the luster of hair — it makes what you already have look better. Coated hair reflects more light, lies flatter, tangles less and snaps less when you comb it.
Hair that breaks less keeps its length. Over a few months that reads, in the mirror, exactly like hair that grew faster. It is not the same thing, but you cannot tell the difference from inside your own bathroom, which is why the belief is so durable.
What castor oil is actually good at
- Holding moisture. It is heavy and occlusive, so it slows water leaving the hair and skin.
- Reducing breakage. Less friction when you comb, fewer split ends taken off at the ends.
- Shine. Measurable, immediate, and the reason it has been in hair preparations for a century.
- Scalp massage. The oil gives you a reason to spend five minutes with your fingertips on your scalp, which people enjoy and which does no harm.
What we changed because of this
Our hair line used to be called Luminous Grow. We renamed it, because the name made a promise the ingredient cannot keep. It cost us the easiest marketing angle in the category and we would do it again — a customer who buys on a false promise is a customer who feels lied to in three months.
If you want something with evidence behind it for hair loss, talk to a doctor about the treatments that have been through trials. We are a cosmetic, not a treatment, and we would rather you heard that from us.
One real risk worth knowing
Is castor oil safe to use on hair?
For most people, yes, used on the outside of the body. It is not a significant skin irritant for most users, but allergy is possible, so patch test a new blend on your inner arm first.
Do not swallow it — castor oil is a laxative, and it can bring on labour, so it is not for anyone pregnant. The castor bean contains ricin; the oil does not, because ricin does not carry over into the oil.
The bottles this applies to
- Luminous Hair — TimberHair & Scalp Oil · 2 oz / 59 mL · $22.00
- Luminous Hair — Alpine HerbsHair & Scalp Oil · 2 oz / 59 mL · $22.00
- Luminous Hair — UnscentedHair & Scalp Oil · 2 oz / 59 mL · $22.00
Sources
Healthline — Does castor oil make your hair grow?
Medical News Today — Castor oil for eyelash growth: does it work?
International Journal of Trichology — Castor oil, the culprit of acute hair felting