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Botanical illustration of Castor Oil
MedicinalSourced entry

Castor Oil

Ricinus communis

Oil pressed from castor seeds, a strong traditional laxative also used to bring on labour. The seeds themselves contain ricin, one of the most toxic plant substances.

Safety at a glance

Tap a box to read the safety notes below. “Nothing recorded” means our sources don't cover it, not that it's safe.

What is Castor Oil?

Plant family
Euphorbiaceae, the spurge family
Parts used
The oil pressed from the seeds; the seeds themselves are poisonous
Where it grows
Grown throughout tropical and subtropical regions
Genus
Ricinus
Species
communis

Also called

Castor, Castor Bean, Castor Oil Plant, Ricinus

Traditionally used for

  • Constipation (traditional)
  • Bringing on labour (studied)
  • Skin and cosmetics

Traditionally described as

  • Strong laxative

Health topics

Where Castor Oil appears in symptom search, and why. Being listed doesn't mean it's a proven treatment.

  • Constipation

    Castor oil is a strong traditional laxative. The seeds are poisonous.

  • Hair Loss

    Traditionally used to thicken and condition hair. A compound in it may block a hair-loss signal in lab research, but it hasn't been tested for hair loss in people.

  • Poisonous Plants

    Raw castor seeds contain ricin and are the main danger; processed oil is generally regarded as safe.

  • Pregnancy and Childbirth

    Can bring on labour; a review of studies in women at full term found it made labour more likely to start. Nausea is common.

How it's prepared

Common ways Castor Oil is prepared or sold. This isn't advice on how to take it; see Safety below.

  • Oil

    Castor oil is taken by mouth as a strong laxative.[1]Study

Safety

Side effects

  • Very rarely, castor oil on the hair has caused hair felting, where the hair suddenly mats into a tangle that can't be combed out and has to be cut off. It can also occasionally cause an allergic skin rash.[2]Study

Pregnancy

  • Castor oil can bring on labour. The studies only included women at full term (37 to 42 weeks), and nausea was common.[3]Review or trial

Toxicity testing

  • Castor seeds contain ricin, one of the most toxic plant substances known. Properly processed castor oil is generally regarded as safe because ricin stays in the seed pulp, not the oil. Raw seeds are the main danger.[1]Study

  • Children can be poisoned by eating castor seeds. In a 2025 case from Nepal, a 6-year-old boy who ate castor seeds became ill with stomach and gut symptoms and needed hospital care.[4]Study

What does the research say?

Traditional use

These are traditional uses, not proven treatments.

  • The castor plant's leaves, roots, seeds and oil have long been used in traditional medicine for pain, inflammation, infections, wounds, gut problems and skin diseases. Castor oil is used as a strong laxative for constipation, and traditional records describe its use to bring on labour, help expel the placenta, and as a purgative for children and older people. It's also widely used in cosmetics and industry.[1]Study

  • Castor oil is a staple of hair and scalp care in African, Caribbean and Indigenous American traditions, especially for textured hair, where it's used to add shine and make hair easier to manage.[2]Study

  • The ancient Egyptians put castor oil on the hair and scalp and thought it essential for thickening hair.[5]Review or trial

Laboratory & animal research

Lab and animal results show what might be worth studying in people. They don't show that the herb has these effects in humans.

  • A substance called prostaglandin D2 slows hair growth and is higher in the scalps of people with male- or female-pattern hair loss. Lab research suggests ricinoleic acid, the main compound in castor oil, may block the enzyme that makes it. It hasn't been tested as a hair-loss treatment in people.[2]Study

Research in people

  • A 2022 review of 12 studies with 1,653 women at full term (37 to 42 weeks) found that castor oil made it about 3 times more likely that labour would start, and more women gave birth vaginally (81% vs 69%). None of the studies reported serious harm, but nausea was common: in one trial, about half the women who took castor oil felt sick.[3]Review or trial

    Technical detail: labour induction RR 3.27 (95% CI 1.96–5.46).

In short

Castor seeds contain ricin, a deadly toxin; the danger is in the seeds, not properly processed oil. Castor oil can bring on labour.

Sources

  1. [1] Phytochemistry, Pharmacological Potential and Industrial Applications of Ricinus communis L.: A Review · DOI: 10.3390/ph19081258Peer-reviewed study
  2. [2] Use of Castor Oil in Dermatology: A Narrative Review · DOI: 10.7759/cureus.103289Peer-reviewed study
  3. [3] Effect and Safety of Castor Oil on Labor Induction and Prevalence of Vaginal Delivery: A Systematic Review and Meta-Analysis · DOI: 10.4103/ijnmr.ijnmr_7_21Review or clinical trial
  4. [4] Pediatric ricin toxicity from castor seed ingestion: a case report from Nepal · DOI: 10.1097/MS9.0000000000003907Peer-reviewed study
  5. [5] Pathophysiology, conventional treatments, and evidence-based herbal remedies of hair loss with a systematic review of controlled clinical trials · DOI: 10.1007/s00210-025-04286-6Review or clinical trial

This information is educational and traditional in nature, and is not a substitute for professional medical advice. Unfamiliar word? See what these words mean.