What Is Castor Oil?

Used for hair health, arthritis, skin health, and more

Castor oil is a natural remedy derived from the castor bean (Ricinus communis). The main component of castor oil is ricinoleic acid, a type of fatty acid shown to possess anti-inflammatory properties. Long used in traditional medicine, castor oil is sometimes taken orally as a laxative, used topically to stimulate hair growth, or applied as a skin lubricant. Some also use castor oil to induce labor in pregnancy or to start the flow of breastmilk.

Not all of these health benefits are supported by scientific evidence.

Castor bean plant
w-ings / Getty Images

What Is Castor Oil Used For?

To date, research on the potential benefits of castor oil is limited. Furthermore, study results regarding castor oil's health effects have been inconsistent. Here's what is known about some popular uses.


Studies investigating castor oil's effect on labor induction have yielded mixed results. A small preliminary study published in 2006 showed that pregnant women at term had an increased rate of labor in the first 24 hours after using the oil. However, study authors recommended further investigation to confirm the benefit.

Later studies involved larger groups of women. A 2009 study in the Australian & New Zealand Journal of Obstetrics & Gynaecology involved 612 women whose pregnancies lasted longer than 40 weeks. Of those women, 205 received castor oil for induction of labor. The study's authors found that the time to birth was not significantly different between those who took the oil and those who did not.


A castor oil pack is created by soaking a cloth in castor oil. When placed on the skin, castor oil packs are thought to enhance circulation and promote healing of the tissues and organs underneath the skin. Some alternative medicine practitioners also use castor oil packs to improve liver function, relieve pain, reduce inflammation, and improve digestion.

Castor oil packs may improve some symptoms of constipation, according to a 2011 study from Complementary Therapies in Clinical Practice. In tests on older patients with constipation, researchers found that seven days of treatment with castor oil packs helped reduce several constipation symptoms, such as straining during defecation. However, castor oil packs failed to have an effect on the number of bowel movements or the amount of feces.


To date, there is no evidence that castor oil can stimulate hair growth. However, preliminary research published in the Journal of Cosmetic Science in 2003 indicates that castor oil may improve hair by increasing its luster.

Indeed, some people use castor oil as a hair conditioner. Others use it to prevent or treat dandruff.


Taking a castor oil supplement may be of some benefit to people with osteoarthritis of the knee, a 2009 study from Phytotherapy Research suggests.

For four weeks, 50 men and women with knee osteoarthritis (age 40 and over) took capsules containing either castor oil or diclofenac sodium (a non-steroidal anti-inflammatory drug) three times daily for four weeks. Results indicated that both treatments were significantly effective at relieving pain associated with osteoarthritis. In the diclofenac sodium group, 90% (45 participants) showed significant improvement in pain levels; in the castor oil group, 92% (46 participants) showed significant improvement in pain levels.

Study authors note that the findings are important because no side effects were associated with the use of castor oil for osteoarthritis in this study. But in the group that took diclofenac sodium, 20% of patients complained of mild gastritis and 4% patients complained of skin rashes.

Skin Health

Many use castor oil as a skin lubricant, to reduce wrinkles, and improve skin quality.

While other plant oils (such as argan oil, avocado oil, and others) have been investigated for these benefits, castor oil has not. Some believe that since other plant oils boost skin health, then castor oil should be able to as well. But this has not been confirmed with scientific evidence.

Other Uses

In addition to the studied uses of castor oil, the product is widely used for other purported benefits. Proponents claim that castor oil can treat a variety of conditions including:

Castor oil has even been used as a contraceptive. There is not enough scientific evidence to know if castor oil is safe or effective for the treatment of any of these conditions.

Possible Side Effects

Swallowing a large amount of oil can be harmful, according to the National Institutes of Health (NIH). Castor oil might also cause fluid and potassium loss from the body when used for more than a week or in doses of more than 15 to 60 milliliters (mL) per day.

Signs of castor oil overdose, which warrant immediate medical attention, include:

  • Abdominal cramps
  • Diarrhea
  • Dizziness
  • Hallucinations
  • Fainting
  • Nausea
  • Shortness of breath and chest pain
  • Throat tightness

Some people experience a rash when using castor oil on the skin. In addition, there is limited evidence that using castor oil on hair may be unsafe.

There is one published report of a rare hair condition called "acute hair felting," where the hair becomes hard, twisted, and entangled. Study authors suggest that castor oil may have been the culprit because the condition occurred following the use of the product for the first time in a healthy individual.

Safety Warning

Consuming a whole castor seed is unsafe. The outer coating (hull) of the castor seed contains a deadly poison that may cause nausea, vomiting, diarrhea, abdominal pain, dehydration, shock, and even death.

Women who are pregnant should consult their provider before consuming castor oil. Parents of children should consult their pediatrician before administering castor oil to their child.

Dosage and Preparation

There are no official recommendations for the proper dosing of castor oil. According to the Natural Medicines Database, different amounts have been used in scientific studies.

For example, in studies investigating constipation, a dose of 15 mL has been used. For cleaning the bowel prior to surgery, a dose of 15 to 60 mL has been studied in adults.

For inducing labor, different amounts have been used with single doses vary from 5 to 120 mL. Never take any steps to induce labor without your healthcare provider's OK.

What to Look For

Castor oil can be found in drugstores, natural-foods stores, and stores specializing in dietary supplements. In addition, castor oil can be purchased online.

Choosing the best castor oil is important. Experts recommend that you look for a reputable brand and, if possible, buy from a familiar vendor such as your local pharmacy.

To get a product that is pure, try to choose organic castor oil and check the label carefully as other ingredients—such as fragrance or less expensive oils—may be added to the product and cause skin irritation.

Cold-pressed castor oil is sometimes preferred because this method helps maintain the oil's natural properties. Unrefined castor oil is also available for those that prefer even less processing.

Store castor oil in a cool, dark place, away from sunlight. If the oil starts to smell foul, it has gone bad and should not be used.

Other Questions

Since castor oil contains ricinoleic acid, is it related to the poison ricin?
Ricin is a potent toxin derived from part of the waste mash produced when beans from the castor plant are processed to make castor oil. Ricin is contained in the hull of the bean, which is discarded in the oil manufacturing process, meaning it does not make its way into the end product.

Ricin made the news when letters containing the toxin were sent to U.S. Congress members and the White House in 2018. According to the Centers for Disease Control and Prevention (CDC), unintentional exposure to ricin is highly unlikely, except through the ingestion of castor beans. However, if you suspect exposure to ricin, the agency suggests that you seek medical help immediately.

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9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  6. Lin TK, Zhong L, Santiago JL. Anti-inflammatory and skin barrier repair effects of topical application of some plant oils. Int J Mol Sci. 2017;19(1). doi:10.3390/ijms19010070

  7. National Institutes of Health. Castor oil overdose: MedlinePlus Medical Encyclopedia. October 2011.

  8. Maduri VR, Vedachalam A, Kiruthika S. Castor oil - the culprit of acute hair felting. Int J Trichology. 2017;9(3):116-118. doi:10.4103/ijt.ijt_22_17

  9. Centers for Disease Control and Prevention. Facts about ricin. National Center for Environmental Health (NCEH). April 2018.

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