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Castor oil is a thick, pale oil pressed from the seeds of the castor plant, Ricinus communis. Taken by mouth, it is an FDA-recognized over-the-counter laxative for occasional constipation; applied to the skin and hair, it is a popular cosmetic ingredient with far weaker evidence behind it. It is also tied to two worries people search for: whether it can start labor, and whether it contains the poison ricin. Below are the castor oil uses FDA actually recognizes, what the labor and hair research found, what the CDC says about ricin, and who should avoid it.
Peptide Labs does not sell castor oil. This article is general information, not medical advice.
Key Takeaways
- Castor oil is listed in FDA's over-the-counter laxative monograph for relief of occasional constipation.
- Laxative labels must warn against use with abdominal pain, nausea or vomiting, or for more than a week without a doctor.
- Labor induction trials are small and low quality, and every trial participant who took it felt nauseous.
- CDC says ricin is found in castor beans and the waste mash left after the oil is made.
- We found no randomized trial showing castor oil alone grows hair in people.
Castor oil for constipation: FDA status
In the United States, castor oil sold as a laxative is an over-the-counter drug, not a dietary supplement. FDA’s Over-the-Counter Monograph M007 for laxative drug products, which took final effect under the 2020 CARES Act, lists castor oil as a stimulant laxative active ingredient. That means a castor oil laxative carries a Drug Facts label, with uses limited to relief of occasional constipation, and must be identified as a stimulant laxative. The monograph’s required wording for oral stimulant laxatives says they generally produce a bowel movement in 6 to 12 hours. Monograph labeling for clinicians also allows castor oil for preparing the colon for x-ray or endoscopic examination, a use that happens under medical direction.
How does it work? In a 2012 study in mice (Tunaru and colleagues, PNAS), ricinoleic acid, the main fatty acid released from castor oil in the gut, switched on a prostaglandin receptor called EP3 in the smooth muscle of the intestine. Mice without that receptor had no laxative response. The same receptor was involved in uterine contractions, which is relevant to the labor question below.
Castor oil is a strong option, not a gentle one, which is why most people with ordinary, occasional constipation start elsewhere. Our guides to fiber for regularity, Metamucil vs MiraLAX, magnesium oxide and probiotics and constipation cover the gentler approaches, and our cascara sagrada guide explains how other herbal stimulant laxatives are regulated. If constipation started with a GLP-1 medicine, see our GLP-1 constipation guide and talk to the prescriber.
Castor oil uses compared
Castor oil turns up in pharmacies, beauty aisles and folk remedies. The table separates what FDA recognizes from what is tradition or marketing.
| Use | Regulatory status | Evidence in people |
|---|---|---|
| Occasional constipation, by mouth | FDA OTC laxative monograph (M007) | Recognized by FDA as safe and effective when labeled as required |
| Bowel prep before x-ray or endoscopy | Monograph labeling for clinicians | Used only under medical direction |
| Starting labor | No FDA-labeled use | Three small, low-quality trials; one large retrospective hospital study |
| Hair growth or thicker eyelashes | Cosmetic use only | No randomized trial of castor oil alone found |
| Skin moisturizing | Cosmetic ingredient | Mostly lab work and narrative reviews |
Castor oil side effects and label warnings
The laxative monograph requires these warnings on castor oil Drug Facts labels, in FDA’s wording or close to it:
- Do not use a laxative when abdominal pain, nausea or vomiting are present unless directed by a doctor.
- If you notice a sudden change in bowel habits that lasts over 2 weeks, ask a doctor before using a laxative.
- Do not use a laxative for longer than 1 week unless directed by a doctor.
- Rectal bleeding, or no bowel movement after using a laxative, may signal a serious condition; stop and call your doctor.
- For children under 2, the directions say to consult a doctor.
MedlinePlus lists the effects of swallowing too much castor oil as abdominal cramps, diarrhea, nausea, dizziness, fainting, chest pain, shortness of breath, skin rash and throat tightness, and, rarely, hallucinations. Its main concern is that uncontrolled diarrhea and nausea can cause dehydration and electrolyte imbalances, which can disturb heart rhythm; our electrolytes guide explains why that matters. If someone swallows too much, call Poison Help at 1-800-222-1222. If you have kidney or heart problems or take diuretics or heart medicines, ask a pharmacist before using any laxative that can cause heavy fluid losses.
Castor oil labor induction: what the research shows
Castor oil has a long folk history as a way to start labor, and the mouse study above gives a plausible mechanism. The human evidence is thin:
- Cochrane review, 2013 (Kelly and colleagues): three trials with 233 women. There was no clear difference in caesarean rates, and the trials reported no data on serious outcomes for mothers or babies. Every woman who took castor oil felt nauseous. The reviewers rated the studies’ quality as poor and said more research is needed.
- German hospital cohort, 2026 (Jakubowski and colleagues): a retrospective review of 1,015 inductions at a university hospital, where 824 women received a castor oil cocktail. Compared with standard methods, the time from induction to delivery was longer on average and more women needed an additional method, with no significant differences in delivery mode or complications. Everyone was monitored in hospital, and the authors called for randomized trials.
The takeaway is not to use castor oil to self-induce. Whether and how to start labor is a decision for your obstetric team, who can monitor you and the baby, and severe diarrhea and dehydration late in pregnancy are real risks. Federal rules also require over-the-counter drugs meant to be absorbed into the body to carry the warning: if pregnant or breastfeeding, ask a health professional before use. At any stage of pregnancy, ask your clinician before using castor oil.
Is there ricin in castor oil?
Ricin is a highly toxic protein, and the CDC states plainly where it lives: it is found naturally in castor beans, and if the beans are chewed and swallowed, the ricin released can cause injury. The CDC also explains that ricin is part of the waste mash produced when castor oil is made. In other words, the danger the CDC describes is in the seeds and the leftover mash. Castor oil sold as a laxative is a regulated drug product. The practical safety point is to keep castor beans and decorative castor plant seeds away from children and pets, and to call Poison Help if someone chews them.
Castor oil for hair, skin and eyelashes
Castor oil for hair is one of the most searched beauty topics, and the claims run well ahead of the evidence. A 2026 narrative review of castor oil in dermatology (Girdler and colleagues) found support for improved hair shine and suggested that ricinoleic acid might influence a hair-loss pathway involving prostaglandin D2, but that idea comes from lab research, and the authors called for clinical studies. When we searched the medical literature, we did not find a randomized trial showing that castor oil alone grows scalp hair, eyelashes or eyebrows in people.
There are also downsides. The same review notes rare contact dermatitis, and a 2025 case report described allergic contact dermatitis from castor oil-containing wound dressings. Castor oil is very thick: a 2017 case report (Maduri and colleagues, International Journal of Trichology) described a woman whose long hair matted into a hard, felted mass right after she applied coconut and castor oil. If you use it as a conditioner or skin oil, try a small area first, keep it out of your eyes, and stop if you get redness or itching. For hair thinning, a dermatologist can look for causes such as thyroid or iron problems; our guides to hair vitamins and collagen and hair review the supplement side, and our sibling guide to cod liver oil covers another traditional oil.
Frequently Asked Questions
Is castor oil FDA approved as a laxative?
Castor oil is listed in FDA’s over-the-counter laxative monograph as a stimulant laxative for relief of occasional constipation, so it can be sold with a Drug Facts label.
How fast does castor oil work?
The monograph’s required label wording says oral stimulant laxatives generally produce a bowel movement in 6 to 12 hours.
Can castor oil induce labor?
Small, low-quality trials do not show clear benefit, and nausea was universal. Do not use it to self-induce; talk to your obstetric team.
Does castor oil contain ricin?
The CDC says ricin is found in castor beans and in the waste mash from making the oil. Chewing the beans is the poisoning risk it describes.
Does castor oil grow hair?
We found no randomized trial showing castor oil alone grows hair in people. It may add shine, and rare cases of hair matting have been reported.
Who should avoid castor oil by mouth?
Anyone with abdominal pain, nausea or vomiting, pregnant people unless their clinician advises it, children unless a doctor directs it, and anyone needing it for more than a week.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider or pharmacist before starting a supplement or an over-the-counter remedy, especially if you take medicines, are pregnant or breastfeeding, or have a food allergy. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Cascara Sagrada and Senna: Stimulant Laxative Rules, Side Effects and Safety, Fiber for Constipation: What the Evidence Says, How Long It Takes and Natural Laxative Foods, Coconut Oil Benefits: Saturated Fat, Research and Virgin vs Refined.