As a medicine, castor oil has a long history of use, even dating back to ancient Egypt. Historically, castor oil was often used as a purgative—a substance that causes the release of waste from the gastrointestinal tract. Probably the best known use of castor oil is for constipation. Taken by mouth, castor oil acts as a stimulant laxative. However, as a laxative, castor oil often causes cramping and abdominal pain due to the intense effects on the smooth muscle of the intestinal tract.
Castor Oil as a Laxative: Not Recommended
While castor oil has a long history of use as a laxative, safer treatments with less side effects are typically recommended. Castor oil frequently causes abdominal cramping, bloating, vomiting, and nausea. Fainting and insomnia are also reported with its oral use (Sani 2010).
When taken by mouth, castor oil is a strong irritant to the lining of the intestinal tract. It can increase intestinal permeability, likely through damage to the lining of the small intestine (Gaginella 1998, Capasso 1994). The oil, when administered in horses, has been suggested as a model for acute colitis or inflammation of the large intestine, further highlighting its harsh nature (Roberts 1989).
Other Uses of Castor Oil
While castor oil acts as an irritant in the gastrointestinal tract, this effect is completely avoided when applied topically. The oil has antioxidant and anti-inflammatory properties that can be useful for a number of applications (Yeboah 2021).
Castor Oil and Muscle or Joint Pain
In fact, castor oil was one of the simplest remedies we provided for patients that were struggling with chronic pain at the clinic. We gave away free castor oil that patients could apply over sore muscles or joints to see if it helped with their symptoms. While not everyone received benefits, enough did that we continued to provide castor oil as an alternative therapy.
A study out of India demonstrates these types of benefits. In women with moderate to severe knee pain, two weeks of castor oil applications combined with 5-10 minutes of heat reduced most of the women’s knee pain from moderate or severe to mild (Roopa 2015). A similar study that compared topical castor oil to a standard anti-inflammatory medication found both treatments to be effective for reducing knee osteoarthritis pain (Medhi 2009).
Castor Oil and Inflammation of the Eyelids (Blepharitis)
Another benefit of castor oil is for the treatment of inflamed eyelids or blepharitis. Blepharitis usually occurs when the oil glands around the eyelashes become clogged. The eyes can feel irritated and the eyelids often turn red and swollen.
One study applied castor oil to the eyelid twice daily for four weeks. Symptom scores of blepharitis were reduced 29% in the treated eyes (Muntz 2021).
Castor Oil Packs
One of the more popular ways to use castor oil is through castor oil packs. Castor oil packs are the application of topical castor oil to the abdomen combined with heat. Typically, a piece of flannel cloth is saturated in castor oil. This is applied to the abdomen and covered with plastic wrap and a towel. A hot pad or hot water bottle is then applied for up to sixty minutes. The heat can help to drive the castor oil through the skin for therapeutic benefits.
While the technique is not well studied, it may provide gastrointestinal benefits without the side effects present with oral use. One study in elderly individuals with constipation found that just three applications were enough to improve constipation symptoms. Notably, unlike standard laxatives, symptoms of urgency and diarrhea were completely avoided with topical castor oil applications (Arslan 2011). The topical treatment helped decrease straining and difficulty with defecation.
Castor oil packs are thought to support liver function. They also may help with uterine cramping and other abdominal symptoms associated with premenstrual syndrome. More research would be useful to better understand the benefits from castor oil packs and their potential applications.
Castor Oil Allergy
While generally quite safe, topical castor oil can cause an allergic response in some sensitized individuals (Brandle 1983). If any redness, itching or irritation occurs directly after its application, wash off the oil and discontinue use.
While not recommended for oral use, topical castor oil appears to have a number of potential benefits. For joint pain, inflammation of the eyelids and abdominal complaints, topical castor oil may be a safe and effective alternative treatment.