Castor oil has been renowned for many years for its benefits on eyelashes. But what about its action on hair? Here’s the answer.
Baldness is the common term for androgenetic alopecia. It is characterized by hair loss on the top of the head. It is estimated that 40% of men over the age of 40 suffer from alopecia, and this figure rises steadily with age.
Genetic predisposition and the effect of androgens (male hormones) are often the two main factors favoring the appearance of baldness. In addition to hair transplants and drug treatments, natural active ingredients are proving to be a therapeutic target in the fight against hair loss.
In this context, ricinoleic acid, a major component of castor oil, has been studied for its ability to block the precursor of prostaglandin D2, which is prevalent in balding men.
This prostaglandin not only miniaturizes hair follicles, but also inhibits hair growth. Ricin oil could therefore be a natural solution for limiting hair loss and preventing the onset of baldness.
A study on baldness
A study has shown that a molecule is responsible for the absence of hair growth in balding men. Researchers have observed that prostaglandin D2 is present in high quantities in the scalps of these men. Prostaglandin D2 is thought to inhibit hair growth.
It also induces hair follicle miniaturization, i.e. a reduction in the diameter of hair follicles. This results in thinner, more fragile hair.
Over time, excessive miniaturization can prevent new hair growth. A second study has shown that ricinoleic acid blocks the production of Prostaglandin D2 synthase (PTGDS), the synthesis product of prostaglandin D2.
Ricinoleic acid is thus seen as a potential target for the treatment of baldness. Ricinoleic acid is found in 80-92% of castor oil.
However, researchers cannot state with certainty that inhibiting prostaglandin D2 will restore hair growth in bald individuals. Further studies or clinical trials are required to confirm this hypothesis.
Operating modes
IN STAND-ALONE MODE
Pour a few drops of castor oil into the palm of your hand. Gently massage the oil into the scalp for better penetration, then leave for 1 hour. Then shampoo as usual. Repeat 1-2 times a week.
IN SYNERGY
In a 100 mL bottle, add :
- 1 tablespoon castor oil
- 3 tablespoons Argan vegetable oil
- 30 drops Ginger essential oil
- 30 drops Atlas Cedar essential oil
Close the bottle, homogenize and label. The synergy is ready to use. It generally keeps for 6 months, protected from air, heat and light.
Apply a sufficient quantity to the scalp, massaging gently for better penetration. Leave on for one hour, then rinse thoroughly.
Then wash hair with your usual shampoo. Avoid contact with eyes, as this product contains substances that are irritating to the mucous membranes of the eye.
What the Science Actually Says
Here is the honest picture. There is no strong clinical evidence that castor oil regrows hair on bald spots caused by androgenetic alopecia. The popular reputation rests on a few things: castor oil is rich in ricinoleic acid, it has anti-inflammatory and antimicrobial properties, and it coats the hair shaft well. Those traits can leave hair looking thicker, shinier, and less prone to breakage, which people often read as “growth.” Real follicle regrowth on a genetically balding crown is a different process, and castor oil has not been shown to drive it.
One often-repeated claim is that ricinoleic acid blocks prostaglandin D2, a compound linked to hair loss. It is an interesting lab idea, but it has not been proven to regrow human hair in studies. Treat it as a maybe, not a fact.
How to Use Castor Oil on the Scalp
- Patch test first. Castor oil is thick and can irritate sensitive skin. Dab a little on your inner arm and wait 24 hours.
- Dilute it. Mix it roughly half and half with a lighter carrier oil such as jojoba, coconut, or argan, since pure castor oil is hard to wash out.
- Massage in. Apply to the scalp and bald spot and massage for a few minutes. The massage itself boosts blood flow, which is part of the appeal.
- Leave and rinse. Leave it on for 30 minutes to a couple of hours, then shampoo thoroughly. Twice a week is plenty.
One Risk Worth Knowing
Castor oil has been linked to a rare problem called acute hair felting, where the hair suddenly tangles into a hard, irreversible mass that often has to be cut off. It is uncommon, but it is the reason you should dilute the oil, avoid heavy application on long hair, and rinse well.
Realistic Expectations
If your goal is healthier looking, less brittle hair, castor oil can earn a place in your routine. If your goal is to regrow a genuinely bald spot from pattern baldness, the treatments with real evidence are minoxidil, finasteride, and for some people hair transplants. Castor oil is a reasonable extra, not a replacement for those. Setting that expectation up front saves a lot of disappointment.
Frequently Asked Questions
How long until castor oil shows results?
Any change in hair condition takes weeks of consistent use. Do not expect new growth on a bald spot, since that is not what the evidence supports.
Can I leave castor oil on overnight?
You can, but dilute it and protect your pillow. Long, heavy applications raise the small risk of tangling.
Is castor oil better than minoxidil?
No. Minoxidil has strong clinical evidence for regrowth. Castor oil mainly improves how existing hair looks and feels.
