What Is Castor Oil?

Used for Hair Health, Arthritis, Skin Health, and More

Castor oil is a vegetable oil derived from the seeds of the castor bean plant, also known as Ricinus communis. The main active 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 can be used orally or topically. It's often used as a laxative, but has also been studied for potential uses in labor induction, arthritis, and skin care.

However, research on many of the potential uses of castor oil is limited.

This article looks at the suggested benefits of castor oil, as well as possible side effects, precautions, interactions, and dosage.

Dietary supplements are not regulated like drugs in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLabs, or NSF. 

However, even if supplements are third-party tested, that doesn’t mean they are necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and to check in about any potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Ricinoleic acid
  • Alternate name(s): Ricinus communis, riccinus oil
  • Legal status: Legal in the U.S. and available over-the-counter
  • Suggested dose: There are no universal dosage requirements for castor oil.
  • Safety considerations: Side effects like abdominal cramping, bloating, and dizziness are possible when using castor oil.

Purported Uses of Castor Oil

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease. 

Castor oil has been suggested to have many health uses, from headaches to menstrual cramps. But the research on the potential benefits of castor oil is limited. Additionally, study results regarding its health effects have been inconsistent.

Below is a look at what is known so far about some of castor oil's most popular uses.

Labor Induction

It has long been claimed that castor oil can induce labor. But studies investigating this claim have shown mixed results.

An observational, retrospective study looked at the use of castor oil to induce, or initiate, labor. The study took place over five years and included women between 40 and 41 weeks pregnant, which is full-term. Compared with the control group, the women who used castor oil showed a higher probability of going into labor within 24 hours.

Another study involved 612 women whose pregnancies lasted longer than 40 weeks. Of these 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.

Castor bean plant
w-ings / Getty Images

Laxative

The Food and Drug Administration (FDA) has approved castor oil's use as a stimulant laxative. It's often used to treat constipation or to prep the bowels for various medical procedures. However, it may not work as well as some other laxatives.

One study compared castor oil to Sena-Graph syrup, another type of laxative, when used as a bowel prep before a procedure. At the end of the study, Sena-Graph syrup was found to cleanse and prepare the bowels more significantly than castor oil. It also caused fewer side effects than castor oil.

Ricinoleic acid is thought to be responsible for the laxative properties of castor oil. Once digested, castor oil is broken down into ricinoleic acid, stimulating the bowels through a series of reactions.

Hair & Skin Care

To date, there is no solid evidence that castor oil can stimulate hair growth, despite numerous claims that it can do so.

However, preliminary research indicated that castor oil might improve the appearance of hair by increasing its luster. This may be why some people use castor oil as a hair conditioner while others use it to prevent or treat dandruff.

Some people also use castor oil for skin care treatment for wrinkles and dry skin. Castor oil is considered an occlusive moisturizer. Castor oil and other natural occlusive moisturizers are said to create a barrier on the skin that locks in moisture and prevents dry skin.

However, while other plant oils have been well investigated for potential skin benefits, castor oil has not. This means that any skin benefits of castor oil have yet to be scientifically proven.

Arthritis

Castor oil has been studied for potential use in relieving symptoms associated with osteoarthritis of the knee.

In the study, men and women over the age of 40 with knee osteoarthritis took capsules containing either castor oil or diclofenac sodium (a nonsteroidal anti-inflammatory drug) three times daily for four weeks.

The results indicated that both treatments were effective at relieving pain associated with osteoarthritis. In the diclofenac sodium group, 90% of participants showed significant improvement in pain levels, while 92% of those in the castor oil group also showed significant improvement in arthritis-associated pain.

The study authors noted that the findings were important because no side effects were associated with the use of castor oil. But in the diclofenac sodium group, about 20% of participants complained of mild gastritis and 4% of participants complained of skin rashes.

What Are the Side Effects of Castor Oil?

It's important to be aware of potential side effects before starting a new supplement or medication. Like most supplements, side effects are possible when using castor oil. These side effects may be mild or severe.

Common Side Effects

Mild side effects have been reported with the use of castor oil. Typically, these and other side effects will subside once castor oil use stops.

Common side effects of castor oil may include:

Anecdotal evidence of a rash developing after using castor oil on the skin has been reported. There has also been limited evidence that using castor oil on hair may be unsafe.

One study discovered a rare hair condition called "acute hair felting," where the hair became hard, twisted, and entangled. These symptoms occurred following the use of castor oil for the first time by healthy individuals.

Severe Side Effects

According to the National Institutes of Health (NIH), swallowing too much castor oil can be harmful. It is possible to overdose on castor oil, which could cause severe consequences.

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

Some of these are similar to the common side effects associated with castor oil, which is why it is important to take it exactly as directed. Talk with your healthcare provider about the right dose of castor oil for you.

Precautions

Castor oil may not be right for everyone, and there are a few precautions to take when using it.

It is recommended that people who are pregnant avoid using castor oil, as it could cause premature contractions.

There is not enough research to know if castor oil is safe for people who are breastfeeding. Because of this, you should consult your healthcare provider before using castor oil. Also, parents should consult their pediatrician before giving castor oil to their children.

It's possible to be allergic to the castor plant, as contact dermatitis has been reported in rare cases after using topical castor oil. Therefore, anyone who is allergic to castor oil should avoid using it.

Ricin, a substance in castor beans, is also worth mentioning.

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. This means it does not make its way into the end product.

Ricin made news when letters containing the toxin were sent to members of Congress 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 recommends that you seek medical help immediately.

Dosage: How Much Castor Oil Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs. 

Castor oil may be used orally or topically in varying amounts. Due to a lack of research, there are no official recommendations for the dosage of castor oil.

In adult males, an appropriate dose of castor oil is said to be 15 to 60 milliliters (mL) a day when used as a laxative. However, this range may not be suitable for everyone. You should follow dosage recommendations from your healthcare provider or as listed on the supplement label.

Taking too much castor oil may cause side effects, so it's important to talk with your healthcare provider about the right dosage for you.

What Happens If I Take Too Much Castor Oil?

It is possible to take too much castor oil, which may cause various side effects.

Generally, castor oil is thought to be safe and non-toxic when used in appropriate amounts. But it is possible to overdose on castor oil.

The castor oil plant, Ricinus communis, contains ricin, which is a known toxin. Fortunately, the ricin is removed from the castor bean in the process of making castor oil. However, large amounts of castor oil are thought to be poisonous.

You should seek immediate medical attention if you think you have overdosed on castor oil. Signs of a castor oil overdose include but are not limited to:

Because it is possible to overdose on castor oil, you should talk with your healthcare provider to determine the proper dosage and instructions for use.

Interactions

Oftentimes, supplements may interact with various medications or other supplements. In the case of castor oil, drug or supplement interactions are not well-documented.

Aside from the lack of evidence, interactions with castor oil may still exist. You should discuss any potential interactions between castor oil and the medications or supplements you're taking with your healthcare provider.

It is vital that you carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. Please review new supplement labels with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications. 

How to Store Castor Oil

Supplements should be stored properly to avoid spoiling.

Store your castor oil supplements in a cool, dry place. They should also be kept out of direct sunlight.

It is also best to keep castor oil and other supplements out of reach of any children or pets in your home.

Discard castor oil supplements once they reach their expiration date as listed on the packaging.

Similar Supplements

Various supplements may work similarly to castor oil. However, it is typically recommended to avoid using multiple supplements for the same purpose at a time. Talk with your healthcare provider about which supplements are best for you.

Similar supplements to castor oil include:

  • Black Cohosh: Black cohosh has been traditionally used by midwives for the natural induction of labor. However, it is recommended that pregnant people use black cohosh with caution and speak with their healthcare provider before using it.
  • Magnesium: Some magnesium supplements, like magnesium oxide, are thought to work like laxatives. After ingestion, magnesium helps pull water to the bowels, an important part of stool formation. It is often used as a laxative in the clinical setting due to its safety.
  • Vitamin D: Vitamin D has been found to have many benefits for human health, including skin health. Studies have shown that dry skin is related to low levels of vitamin D in the body. Because of this, using vitamin D supplements is thought to improve skin hydration.
  • Boswellia: Also known as Indian frankincense, Boswellia has been used for the treatment of osteoarthritis. One systemic review looked at several studies and found Boswellia could relieve pain associated with osteoarthritis. The supplement was also found to be a safe option.

No supplement should replace standard medical care. Always seek medical guidance from a healthcare provider.

Remember to talk with your healthcare provider about the right supplement choice for you.

Frequently Asked Questions

  • Is castor oil toxic?

    Castor oil is not thought to be toxic. Although, the castor bean from which it comes can be toxic.

    Castor beans contain a substance called ricin, which is poisonous when intact. However, once castor beans are processed and used to make castor oil, the ricin is destroyed and is not present in the oil.

  • Does castor oil induce labor?

    Some use castor oil as a natural way to induce labor.

    In one study, 323 women used a castor oil cocktail to induce labor. Of these women, almost 91% had a subsequent vaginal birth with few complications or side effects related to using castor oil. You should always talk to your healthcare provider before using any supplement, especially while pregnant.

  • Is castor oil good for hair?

    Research has been mixed regarding the use of castor oil for hair.

    One older study found that castor oil could improve hair luster, or shine. However, other research has reported castor oil's ability to cause something called hair felting, in which hair becomes twisted and matted, almost like a bird's nest.

Sources of Castor Oil & What to Look For

Castor oil is not widely found in foods and is mostly used in supplement form.

Castor Oil Supplements

Castor oil can be used either orally or topically. It is available as a serum, soft gel, or oil.

Some castor oil supplements are cold-pressed and unrefined, while others are a bit more processed. Typically, castor oil supplements are both vegan and gluten-free.

It is recommended that you look for a reputable castor oil brand and, if possible, buy from a familiar vendor such as your local pharmacy. It's also important to read the castor oil label carefully, as potentially irritating fragrances are sometimes added.

Summary

Many people associate castor oil as being a treatment for constipation. It has also been studied for other potential uses, like inducing labor, relieving arthritis pain, and moisturizing skin. However, many of these claimed benefits of castor oil are not well-supported by evidence.

Castor oil supplements can cause side effects, including diarrhea, abdominal cramps, nausea, rash, and even hallucinations in some cases. You should be aware of any precautions or interactions associated with castor oil, so be sure to talk with your healthcare provider before using it.

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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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Additional Reading

By Brittany Lubeck, RD
Brittany Lubeck, RD, is a nutrition writer and registered dietitian with a master's degree in clinical nutrition. 

Originally written by
Cathy Wong
Cathy Wong

Cathy Wong is a nutritionist and wellness expert. Her work is regularly featured in media such as First For Women, Woman's World, and Natural Health.

Learn about our editorial process