Do Castor Oil Packs Help Menstrual Pain?
Filling the data void
Castor oil packs for painful periods and endometriosis pain are popular on social media right now. Is there any evidence to support their use?
What is Castor Oil
Castor oil is a vegetable oil extracted from castor beans, which are the seeds of the Ricinus communis plant. It has been used for thousands of years as an emollient for the skin, oil for lamps, and various medicinal reasons. When taken orally, it can cause vomiting and diarrhea, which is likely why it was considered medicinal, either because people believed it restored “balance” or simply because the drama of the vomiting/diarrhea provided the illusion of effectiveness. Just because people used something medicinally thousands of years ago doesn’t mean it has the ascribed medicinal properties.
One very important thing to know about Ricinus communis is that the seeds (castor beans) contain ricin, a deadly poison. Ricin is absent in commercial preparations as it is removed while producing commercial castor oil, but this is why you should NEVER attempt to make castor oil at home.
What are the Uses of Castor Oil?
The only known medical use is as an oral therapy for constipation, so the Food and Drug Administration FDA classifies it as a laxative. Specifically, it’s a stimulant laxative that stimulates the bowel to contract, pushing stool along. It is generally recognized as safe and effective for this reason, but the diarrhea can be violent, so it’s not commonly used. You may see claims that castor oil is FDA-approved for constipation, but that isn’t exactly correct, as over-the-counter (OTC) medications are not FDA-approved. Instead, the FDA has a monograph listing the acceptable ingredients, doses, and formulations for OTC drugs and their acceptable applications. If an OTC product conforms to that recipe book, it can be sold without FDA pre-approval.
Castor oil is also found in many cosmetics, where it functions as an emollient, emulsion stabilizer, and surfactant. Castor oil is also occlusive, meaning it creates a physical barrier on the skin that prevents water loss, helping keep the skin hydrated.
How is Castor Oil Used for Menstrual and Endometriosis Pain?
The oil is applied to the abdomen, and then a cloth wrap is used to hold it in place, or the castor oil is applied directly to the wrap first, which is then placed against the skin. Some people apply a hot water bottle over top, and others don’t. There are also disposable, self-adhesive castor oil pads like these on Amazon. Notice the bullshit about a “liver detox.”
What About Castor Oil For Pain?
No data supports its use, and I can’t find that it has been studied meaningfully. What we know about the chemistry also doesn’t support the topical use of castor oil for pain as ricinoleic acid, the main fatty acid in castor oil doesn’t penetrate through the skin, so it can’t access muscles or fat or enter the bloodstream. Any benefit from castor oil packs likely comes from massage (if it’s being massaged into the skin), the pressure from the wrapping, or the heat (if used). The ritual of applying a castor oil pack might be self-care, which could also make someone feel better. If it gives time to pause and do some slow, deep breaths (diaphragmatic breathing), that may also help with pain. And there is always the possibility of a placebo response. I don’t want to downplay how applying an oil, wrapping, or heat might make some people feel better, but there is no evidence to suggest that topical castor oil is better than any other vegetable oil or that the oil is doing anything biological for pain.
There are some naturopaths, chiropractors, and influencers who apparently believe castor oil can activate mysterious parts of the immune or endocrine system or penetrate the skin and do something “medicinal” (what specifically from a pain perspective is never stated). Given its widespread and longstanding use in cosmetics, we'd likely know if a bioactive chemical from castor oil could be absorbed to treat pain (or do anything else). I double-checked with Dr. Michelle Wong, who has her Ph.D. in chemistry and is a science educator and cosmetic chemist (you may know her as Lab Muffin, and she is well worth the follow on social media), and she told me castor oil would “only get into the very top layers” of the skin.
The origin of castor oil for menstrual pain/endometriosis pain likely came from the belief that it can induce labor when taken orally, but how something could stimulate painful uterine contractions in pregnancy and yet make them less painful during menstruation is quite the conundrum.
What’s The Harm of Castor Oil Packs?
If someone tried them and found they helped, great, but as a doctor, I couldn’t recommend them over a hot water bottle. I could recommend a TENS unit, as those have been shown to help reduce menstrual pain.
If heat is used with a castor oil pack (the same goes for a hot water bottle or heating pad), it’s important to be mindful of chronic long-term heat exposure, as this can produce a rash on the skin called erythema ab igne. To prevent this, heat shouldn’t be used for more than 15 minutes at a time, and if mottling or redness persists on the skin once the heat is withdrawn, stopping exposure to heat is necessary.
The real harm with castor oil packs is the disinformation that is often (really often) found on websites that promote their use. Take a look at this kit, making bullshit claims about liver detox, lymphatic drainage, balancing hormones, and so on. None of these benefits are remotely plausible. It reads like an untrained AI was asked to write the copy.
Other health claims about castor oil packs that I have seen from a motley crew of naturopaths, menstrual coaches, and chiropractors include the following:
“Detoxification,” which I guess is a more general detox than the liver detox? The words “detox” and “detoxification” should function like a pop-up warning to let you know that you are in a medical bullshit zone.
“Treatment of constipation and loose stools,” a.k.a. covering your bases. The idea that there is one product (a laxative, no less) that, when applied topically, can treat both constipation and loose stools is ludicrous.
“Treat fatty liver and gallstones”…nope, nope, nope.
“Regulate periods.” I mean, no. Not possible with human physiology.
Shrink uterine fibroids. The idea here, I suppose, is there is something “special” in castor oil that can either recruit special fibroid-destroying chemicals or seep through the skin, fat, and muscles of the abdominal wall, then penetrate the uterus but dissolve only the fibroids while leaving the rest of the uterus untouched. This is biologically absurd. How naturopaths, chiropractors, and influencers would know about this miraculous yet secret substance, and yet its existence has been ignored by the world of science is…something.
I could go on with the “That’s Incredible!” list of the miracle wonders of castor oil, but I sprained my eyes rolling back into my head. I guess you can’t sell oil and special wraps if you are honest and say, “Some people find this makes them feel better.”
The real harm of castor oil packs is that they could be a gateway into the wide world of serious medical disinformation.
Summary
If you want to use castor oil packs, know that the oil doesn’t penetrate deeper than your skin. However, the pressure from the wrap, the feel of the oil, the heat (if used), or the time spent caring for yourself may help. Just be wary of people who promote castor oil packs as medicine because they are often peddling disinformation. While castor oil is a fine emollient and will likely leave your skin feeling soft, the benefits of the oil itself are only skin-deep.
References
Final report on the safety assessment of Ricinus Communis (Castor) Seed Oil, Hydrogenated Castor Oil, Glyceryl Ricinoleate, Glyceryl Ricinoleate SE, Ricinoleic Acid, Potassium Ricinoleate, Sodium Ricinoleate, Zinc Ricinoleate, Cetyl Ricinoleate, Ethyl Ricinoleate, Glycol Ricinoleate, Isopropyl Ricinoleate, Methyl Ricinoleate, and Octyldodecyl Ricinoleate. Int J Toxicol. 2007;26 Suppl 3:31-77. doi: 10.1080/10915810701663150
Elboim-Gabyzon M, Kalichman L. Transcutaneous Electrical Nerve Stimulation (TENS) for Primary Dysmenorrhea: An Overview. Int J Womens Health. 2020 Jan 8;12:1-10. doi: 10.2147/IJWH.S220523.
"Just because people used something medicinally thousands of years ago doesn’t mean it has the ascribed medicinal properties" This! Social media platforms should be mandated to add this warning to all influencers grifting these products.
Thank you for this! I used a recipe that I found in a popular herbal book for pregnancy for Castor oil with orange juice and vodka to induce labour 26 years ago. I was already 42+weeks pregnant and having on and off labour pains, so no idea if the castor oil worked, BUT, I would recommend it if you would like hemorrhoids along with the episostomy or vaginal tear, and I have never ordered vodka and orange juice at a bar since.