Castor Oil Benefits: What the Research Shows

Castor oil is a thick plant oil pressed from castor seeds, and its reputation runs well ahead of the evidence. The only use the FDA has approved is as a laxative; for hair, lashes and skin the research is a lab test, animal studies and one cream trial. This guide separates what was measured from what labels claim.

We sell a Pure Castor Oil, so read this with that in mind. Where our own listing says more than the sources do, this page says so. For the closest comparison oil with its own write-up, see our jojoba oil for eyelashes guide.

What Is Castor Oil, and What Is in It?

Castor oil is pressed from the seeds of the Ricinus communis plant, and about 90% of its fatty acids are ricinoleic acid. A 2026 narrative review in Cureus calls that fatty acid largely responsible for the oil's distinctive chemistry.

• What it is: A vegetable oil. StatPearls notes it is also used outside medicine, in lubrication, cosmetics and coatings.
• The ricin question: The castor plant contains the toxin ricin, but StatPearls says ricin is water soluble, so the extraction process negates its toxic properties.
• Plain versus hydrogenated: Cosmetic ingredient lists include both plain castor seed oil and hydrogenated castor oil. The reports of allergic reactions below are mostly tied to the plain oil.

Is Castor Oil Proven to Help Hair Grow?

No. We found no human trial showing it grows hair, and the Cureus review says many of the hair claims are cultural practices that have not been studied for clinical efficacy.

• What was measured: A 2003 lab study in the Journal of Cosmetic Science used image analysis on hair tresses and found castor oil increased luster by changing the contrast between reflected light. That is shine on the fiber, not growth.
• What is preclinical: The review describes lab work in which ricinoleic acid binds and inhibits an enzyme, prostaglandin D2 synthase, tied to pattern hair loss. It says the clinical translation for androgenetic alopecia remains uncertain and needs more investigation.
• What that means: A shinier strand and a lab finding are not the same as more hair. Anyone selling castor oil as a growth product is going beyond what we found.

Does Castor Oil Grow Eyelashes and Eyebrows?

We found no trial showing it does. Medical News Today’s review of the question says there is no scientific evidence that castor oil helps eyelashes grow, though it may make them look thicker or glossier.

• What an eye doctor says: Asked whether cold-pressed castor oil is safe in the eyes, an ophthalmologist answering for the American Academy of Ophthalmology said he does not recommend any non-sterile materials in the eye and suggested seeing an ophthalmologist for safer products.
• Our own label: Our Pure Castor Oil label says external use only and to avoid contact with eyes, so we do not give a lash or brow routine here. The lash and brow steps on our listing are the part we cannot source.
• A comparison: Our jojoba oil for eyelashes guide reaches the same conclusion on growth for a lighter oil.

Does Castor Oil Help Skin?

It may soften and moisturize, but the evidence is early. The Cureus review concludes castor oil shows promise and needs further clinical investigation, and says much of its use rests on anecdotal evidence or preclinical findings.

• The cream trial: The review describes a single-arm trial of a castor oil cream applied twice daily around the eyes for two months, with reported drops in melanin, redness and skin laxity and a 33% improvement in a wrinkle score (2.45 to 1.64). It had no comparison group and tested a cream, not plain oil.
• The animal study: A 2000 study in Mediators of Inflammation found that repeated topical ricinoleic acid reduced paw swelling in mice, and called it a capsaicin-like, non-pungent agent for peripheral use. That is animal data, not skin-care proof.
• Elasticity: The review also describes a short test in which skin elasticity rose two hours after a lotion was applied. That lotion contained salts made from castor oil rather than plain oil, and long-term results are unknown.

Is Castor Oil Safe to Put on Skin and Hair?

Usually, but not for everyone. The review says adverse reactions are rare and typically mild, but its case reports include allergic contact dermatitis, most often with plain castor oil, and it names ricinoleic acid as the likely trigger.

• Allergy cases: Reports include armpit dermatitis after a deodorant containing hydrogenated castor oil, where the patient reacted on patch testing to undiluted castor oil, and lip reactions linked to lipsticks. StatPearls also lists castor oil in lip products as a possible trigger.
• Hair felting: One case report describes hair that suddenly matted and could not be untangled right after a first castor oil application, and had to be cut off. It is a single report, but it is a reason to start with a small section.
• Natural is not allergy-proof: The American Academy of Dermatology quotes a dermatologist saying that all natural in no way means a product is unlikely to cause allergies. Patch test first.

Is It Safe to Swallow Castor Oil?

Only as a medical laxative, and not in pregnancy. StatPearls says the FDA has approved castor oil only as a stimulant laxative for the temporary relief of occasional constipation, and that other laxatives are usually better tolerated.

• Side effects: In a comparison with senna, castor oil was more likely to cause abdominal cramping, vomiting, bloating and dizziness.
• Pregnancy: StatPearls says ingesting castor oil during pregnancy may induce labor, so use as a laxative is contraindicated. Ask a clinician before using it by mouth for any reason.
• Our bottle: Our Pure Castor Oil is labeled for external use only. Do not drink it.

How Do You Use Castor Oil on Skin or Hair?

Patch test first, then use a small amount, away from your eyes. No source we read gives a tested routine for plain castor oil, so these steps adapt our own listing and the allergy precautions above; the amounts are our suggestion.

1. Patch test. Put a drop on your inner forearm and wait a day, because natural does not rule out an allergy.
2. Keep it away from your eyes. Our label says to avoid contact with eyes, and an ophthalmologist advises against non-sterile materials in the eye.
3. Thin it for large areas. It is very thick. Our listing suggests mixing it 1:1 with sweet almond or jojoba oil to spread it; that is a tradition, not a tested ratio.
4. For the scalp, warm a small amount and massage it in. Our listing suggests leaving it on for at least 30 minutes before shampooing, and says two washes may be needed. There is no evidence this grows hair; the lab study found only added shine.
5. Stop if it irritates. Stop if you notice itching, redness, swelling or tangling, and wash it off.

What Does Our Pure Castor Oil Say, and What Do the Sources Support?

Our oil is a single ingredient, Ricinus Communis (Castor) Seed Oil, in a single bottle, but several lines on the listing go further than the sources. The listing says cold-pressed and hexane-free.

• Supported: The oil is about 90% ricinoleic acid, which matches the review's composition figure. We could not verify the listing's line that this is the highest concentration of any plant oil on earth, so we do not repeat it.
• Not supported by what we read: Lash and brow conditioning, support for scalp circulation and growth, and joint and muscle use. We found no human trial for these, and the listing's line that ricinoleic acid has been studied for inflammation rests on the animal work above.
• A conflict: The listing gives lash and brow application steps, while its own label says to avoid contact with eyes.
• Where it fits: A thick single-ingredient oil for body and hair, not a proven growth product. For lighter oils used on the face, see our guide to facial oils for dry skin.

When Should You See a Doctor About Castor Oil?

See one before swallowing it, and for hair loss, eye irritation or a skin reaction that does not settle. This guide is information, not medical advice.

Hair loss has many causes, and a dermatologist can look for them; castor oil has not been shown to fix any of them. For eye redness, pain or vision changes after any product near the eyes, see an ophthalmologist. If a rash, swelling or itching follows castor oil, stop using it and have a clinician look.

Frequently Asked Questions

What is castor oil good for?

The FDA has approved it only as a stimulant laxative for occasional constipation. For skin and hair the evidence is early: one cream trial, animal data and a lab test of hair shine.

Does castor oil make hair grow?

We found no human trial showing it does. A 2003 lab study found it increased hair luster, and lab work on ricinoleic acid has not been shown to translate into hair growth.

Is castor oil safe on eyelashes?

It is not established. We found no trial for lashes, an ophthalmologist advises against non-sterile materials in the eye, and our own label says to avoid contact with eyes.

Can you drink castor oil?

It is an approved stimulant laxative, but it caused more cramping and vomiting than senna in one comparison and is contraindicated in pregnancy. Our bottle is for external use only.

Does castor oil contain ricin?

The plant does; the oil is not meant to. StatPearls says ricin is water soluble, so the extraction process negates its toxic properties.

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