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Castor Oil

Other common name(s): castor, castor bean, palma christi, Mexico seed, oil plant, mole bean

Scientific/medical name(s): Ricinus communis


Castor oil is extracted from the seeds of Ricinus communis, an herb native to Africa and India. For most uses described here, castor oil is applied to the skin rather than swallowed, but it can be taken by mouth.


Available scientific evidence does not support claims that applying castor oil to the skin (called topical use) is effective in preventing or treating cancer. Taken by mouth, castor oil works as a laxative. And, castor oil is used in mainstream medicine as a way to deliver chemotherapy drugs to cancerous tumors.

How is it promoted for use?

Castor oil, taken by mouth, has been used as a laxative for many years. It may also be used to treat some eye irritations and skin conditions and is used in mainstream medicine to deliver chemotherapy drugs to cancerous tumors.

Naturopathic practitioners (see our document, Naturopathy) and some others claim that castor oil boosts the immune system by increasing white blood cells, which help the body fight infection, and other immune cells. Some also claim that castor oil can help "dissolve" cysts, warts, and tumors, as well as soften bunions and corns. Other claims for castor oil include treating lymphoma, bacterial and viral diseases (including HIV), arthritis, skin and hair conditions, eye irritations, diseases of the colon and gallbladder, bursitis, multiple sclerosis, and Parkinson disease. It is also promoted as a way to "detox" the body and stimulate digestion.

What does it involve?

Treatment involves massaging castor oil into the body or using a warm or hot castor oil pack or compress. The castor oil is massaged along the problem region, spine, abdomen, and sites (or pathways) of lymphatic drainage. If using a compress, the warm castor oil pack is placed over the affected joint or organ and left in place for up to an hour. Promoters say castor oil should be applied until the problem is healed.

Some treatments may include taking small amounts of castor oil by mouth.

What is the history behind it?

Ancient Egyptians were the first to record the use of castor oil for medicinal purposes, and since then it has been used by many cultures as a folk medicine. Castor oil was reportedly used as a medicine during the early Middle Ages in Europe. Edgar Cayce, a medium who entered a trance state to offer patients his thoughts about their diagnosis (and past lives) claimed that castor oil helped to heal the lymphatic tissue in the small intestines, thus increasing absorption of fatty acids and allowing for tissue growth and repair. Most of the plants used in producing castor oil are now grown in India and Brazil.

What is the evidence?

Available scientific evidence does not support claims that castor oil on the skin cures cancer or any other disease. Castor oil is taken by mouth in conventional medicine as a laxative and used as an eye drop to treat some eye irritations. It is also an ingredient in some hair conditioners and skin products. Available scientific evidence does not support other claims.

Oncologists now use castor oil as a vehicle for delivering some chemotherapy drugs to cancerous tumors. A special formula of castor oil called Cremophor EL is used as a carrier for paclitaxel, a drug used to treat metastatic breast cancer and other tumors. Unfortunately, the vehicle sometimes causes problems of its own, including allergic reactions. This has prompted a search for substitute carriers.

Researchers have been studying ricin, a strong poison produced by the castor bean, for a few years now. Most of the studies so far have been done in the lab rather than in humans. But early clinical trials suggest that when combined with an antibody to guide this poison to the malignant cells, ricin may shrink tumors in lymphoma patients.

Ricin is a possible bioterrorism agent, since inhaling, swallowing, or being injected with very small amounts can cause severe illness and death.

Are there any possible problems or complications?

This product is sold as a dietary supplement in the United States. Unlike companies that produce drugs (which must be tested before being sold), the companies that make supplements are not required to prove to the Food and Drug Administration that their supplements are safe or effective, as long as they don't claim the supplements can prevent, treat, or cure any specific disease.
Some such products may not contain the amount of the herb or substance that is on the label, and some may include other substances (contaminants). Actual amounts per dose may vary between brands or even between different batches of the same brand. In 2007, the FDA wrote new rules to improve the quality of manufacturing for dietary supplements and the proper listing of supplement ingredients. But these rules do not address the safety of the ingredients or their effects on health.
Most such supplements have not been tested to find out if they interact with medicines, foods, or other herbs and supplements. Even though some reports of interactions and harmful effects may be published, full studies of interactions and effects are not often available. Because of these limitations, any information on ill effects and interactions below should be considered incomplete.

Castor oil is considered safe in proper doses for conventional uses as a laxative. However, side effects can include abdominal pain or cramping, colic, nausea, vomiting, and diarrhea. Long-term use of castor oil can lead to fluid and electrolyte loss.

Women who are pregnant or breast-feeding should not use castor oil, nor should people with intestinal blockage, acute inflammatory intestinal disease, appendicitis, or abdominal pain. Medicines that are dissolved in or based on castor oil compounds can cause allergic reactions.

Castor beans are extremely poisonous and can kill people or animals if chewed or swallowed. Also, handling the seeds can lead to allergic reactions.

Relying on this treatment alone and delaying or avoiding conventional medical care for cancer may have serious health consequences.

Additional resources

More information from your American Cancer Society

The following information on complementary and alternative therapies may also be helpful to you. These materials may be found on our Web site (www.cancer.org) or ordered from our toll-free number (1-800-227-2345).

Dietary Supplements: What Is Safe?

The ACS Operational Statement on Complementary and Alternative Methods of Cancer Management

Complementary and Alternative Methods and Cancer

Placebo Effect

Learning About New Ways to Treat Cancer

Learning About New Ways to Prevent Cancer


Belson MG, Schier JG, Patel MM, Case Definitions for Chemical Poisoning. MMWR. 2005; 54(RR01);1-24.

Bown D. Encyclopedia of Herbs & Their Uses. New York, NY: DK Publishing Inc; 1995.

Fetrow CW, Avila JR. Professional's Handbook of Complementary and Alternative Medicines. Springhouse, Pa: Springhouse Corp; 1999.

Fjällskog ML, Frii L, Bergh J. Paclitaxel-induced cytotoxicity the effects of cremophor EL (castor oil) on two human breast cancer cell lines with acquired multidrug resistant phenotype and induced expression of the permeability glycoprotein. Eur J Cancer. 1994;30A:687-690.

Gruenwald J. PDR for Herbal Medicines. 3rd ed. Montvale, NJ: Thomson PDR; 2004.

Henderson CW. Researchers know beans about cancer research. Cancer Weekly Plus. Accessed at: www.newsrx.com/newsletters/Cancer-Weekly/1998-11-02/1998110233329CW.html on December 2, 2010.

Karp RA. Edgar Cayce Encyclopedia of Healing. New York: Warner Books Inc. 1986.

Price KS, Castells MC. Taxol reactions. Allergy Asthma Proc. 2002;23:205-208.

Rischin D, Webster LK, Millward MJ, et al. Cremophor pharmacokinetics in patients receiving 3-, 6-, and 24-hour infusions of paclitaxel. J Natl Cancer Inst. 1996;88:1297-1301.

UPMC Center for Biosecurity. Ricin Fact Sheet. Accessed at http://www.upmc-biosecurity.org/website/focus/agents_diseases/fact_sheets/ricin.html on December 3, 2010.

Note: This information may not cover all possible claims, uses, actions, precautions, side effects or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for consultation with your doctor, who is familiar with your medical situation.

Last Medical Review: 03/07/2011
Last Revised: 03/07/2011