What is it?
A thick oil pressed from the seeds of the castor plant, Ricinus communis. Ricinoleic acid makes up 87 to 90 percent of its fatty acids. In cosmetics it works mainly as a skin-conditioning ingredient and is used at high levels in lipsticks; it also appears in lip balms, moisturizers and hair oils. Taken by mouth, it is a stimulant laxative.
Key information
- The CIR Expert Panel concluded in 2007 that castor oil is safe as used in cosmetics and reaffirmed that conclusion in 2025.
- Castor oil does not contain ricin: the poison stays behind in the leftover seed mash because it does not pass into the oil.
- Allergy to castor oil is uncommon but has been reported, mostly as lip dermatitis from lipsticks and lip balms.
More information
Castor oil is made by cold-pressing castor seeds and then clarifying the oil with heat. The seeds also contain ricin, a poison, but ricin dissolves in water, not oil, and ends up in the waste mash left after pressing, as the CDC also notes. The Cosmetic Ingredient Review (CIR) concluded that castor oil does not contain ricin, provided it is not cross-contaminated during production.
The CIR Expert Panel concluded in 2007 that castor oil and related ricinoleates are safe as used in cosmetics and reaffirmed that in a re-review published in 2025. Castor oil was then used at up to 81 percent in lipsticks; industry data from 2023 list it in more than 1,000 products. In human tests it was not a significant skin irritant, sensitizer or photosensitizer. The CIR report also notes that the FDA classifies castor oil as generally recognized as safe and effective as a stimulant laxative, a use outside this profile.
Allergic reactions do occur. Case reports reviewed by CIR describe lip dermatitis from lipsticks and lip balms containing castor oil or its main fatty acid, ricinoleic acid, and people with existing skin conditions from workplace exposures may react. A 2026 dermatology review reports that hydrogenated and PEG-modified castor oils carry a lower risk of this allergy.
Reality check: castor oil is a traditional hair oil and is also applied as “castor oil packs.” The 2026 review found that much of this use rests on anecdote or laboratory findings, and that more research is needed before castor oil can be established for hair loss. It also notes rare cases of sudden, severe matting of the hair (hair felting). On labels, look for Ricinus Communis (Castor) Seed Oil; PEG castor oils are different ingredients, covered in our PEG profile.
Sources: CIR: Re-review of Ricinus Communis (Castor) Seed Oil and Ricinoleates, including the 2007 final report (2024); International Journal of Toxicology (2025): Re-review summary of Ricinus Communis (Castor) Seed Oil and ricinoleates; CDC: Ricin fact sheet; Cureus (2026): Use of castor oil in dermatology: a narrative review
