The 19th-century American humorist Josh Billings once said: “Advice is like castor oil, easy enough to give but dreadful uneasy to take.” Although “dreadful uneasy to take,” consumers seem to hold the colorless oil in high esteem.
But are the health claims about castor seed oil circulating on the internet true? Or is this a billion-dollar industry’s way of generating even more interest in its product?
Castor Oil’s Modern Therapeutic Relevance
The Food and Drug Administration (FDA) approves castor oil as a stimulative laxative, meaning that officials recognize the benefits of application in cases of constipation and see value in the oil’s use in certain types of medical procedures; for example, during the preparation of the bowel before a colonoscopy.The FDA also acknowledges that castor oil has been used in alternative medicine for centuries, yet, the lack of certain research prohibits the agency from approving further medicinal uses. The research that does exist, however, is encouraging.
A review article about the pharmacological activities of the castor bean plant (Ricinus communis) that was published in the Pakistan Journal of Pharmaceutical Sciences in 2017 found that although constituents such as ricin and ricinine give the plant toxic effects, on the other hand, “the compounds have been reported to exhibit, antidiabetic, anti-inflammatory, antimicrobial, antioxidant, hepatoprotective, and wound-healing activities.”
The study mentions an extensive list of ailments for which the long-established use of castor oil has been recommended in traditional medicine. Examples include abdominal disorders, constipation, arthritis, rheumatism, muscle aches, chronic headaches, gallbladder pain, and menstrual cramps, as well as insomnia, to name a few.
Soothing to Skin
Castor oil has demonstrated moisturizing qualities and may increase collagen production, one animal study suggests. Its antibacterial, antioxidant, and anti-inflammatory properties make castor oil a favorable ingredient in biocidal wound dressings, lotions, and creams treating acne, redness, or other irritations of the skin, as well as after-sun products.Even hyperpigmentation, caused by an increased production or distribution of melanin, can be treated with castor oil. Those dark skin spots were the topic of a dermatological clinical trial in which 25 patients were instructed to use castor oil cream twice daily for two months. Results indicated that the therapy “significantly reduced the melanin level, wrinkles, and skin laxity” in treated areas.
The Journal of Oleo Science concerns itself primarily with the properties of oils and fats. The authors of a 2022 article confirmed castor oil’s usefulness “as a bactericidal, anti-inflammatory, and antiherpetic agent,” which makes it a valuable anti-viral in cold sore formulations and other herpes virus treatments.
Based on all of these favorable qualities, the cosmetic industry uses castor oil as an ingredient that shields the skin against environmental influences. Furthermore, it functions as an agent against premature aging of the skin. It reduces wrinkles and prevents new ones from developing, especially in combination with virgin coconut oil, another study finds.
Calming to the Eyes
In addition, castor oil seems a suitable, safe, and tolerable therapeutic agent for people suffering from dry eyes, blepharitis (inflammation and swelling of the eyelids sometimes caused by an overgrowth of microscopic mites), or meibomian gland dysfunction. The oil displays “strong anti-microbial, anti-inflammatory, anti-nociceptive, analgesic, antioxidant, wound healing and vaso-constrictive properties,” states a 2021 review published in Clinical and Experimental Optometry. Studies included in the review indicated that a topical application of castor oil increased the tear film layer and improved diagnosing capabilities through ocular surface staining tests.However, other sources suggest that castor oil’s non-sterility may be a reason not to use it in the eyes.
Enhances Hair Growth and Suppleness
Indigenous knowledge of hair oils and their usage was published in a 2022 review, which showed that castor oil adds moisture to the hair, nourishes hair follicles, and protects against scalp irritation. Its fungicidal qualities also counteract dandruff, as well as other “fungal and microbial infections.” In addition, the oil might even aid hair growth.The combination of castor oil’s properties may provide hair with extra shine and elasticity, and soothe dry and red scalp.
Another study, titled “Bioactive-Based Cosmeceuticals: An Update on Emerging Trends,” cites castor oil as being “used as a component in hair oils, as it moisturizes the scalp, eases dandruff and, additionally, complements the fitness of hair follicles and, in turn, promotes hair growth.”
Conversely, a 2022 review published in the Journal of Drugs in Dermatology evaluated 22 articles on the topic of hair oils in “skin of color patients.” Although castor oil showed some evidence of “improving hair quality by increasing hair luster,” the remedy’s performance was weak regarding hair growth. In this case, coconut oil outranked castor oil.
Promotes Healthy Nails
Castor oil is a common ingredient in cuticle softeners, nail creams, and hand lotions—it’s also in nail polish and enamel removers.Its healing antimicrobial qualities come to fruition when used against toe and fingernail fungus. An Italian study examined 25 patients and treated them with a new formulation featuring castor oil as one of its main ingredients. Sixty percent of treated individuals were healed completely within five months of using the topical application.
“Skin absorption” is a way for various substances or medicinal products to enter the body from the outside via the skin. When castor oil is utilized in the form of castor oil packs, the body benefits from the skin’s ability to assimilate the medicinal properties of the oil. This treatment method is mainly used when targeting internal maladies.
Castor Oil and the Digestive Tract
A clinical trial in elderly patients who had suffered from constipation for a decade or longer showed that castor oil packs could help to treat this ailment. Although the frequency of bowel movements did not increase, the treatment did affect excrement consistency and made it easier to pass, leading to less straining.Castor oil’s clearing effects as a stimulant laxative seem to be common knowledge. Ingest a tablespoon or two of the oil on an empty stomach, and a few hours later, relief in the form of a visit to the bathroom should set in. However, bowel evacuation studies have also reported side effects such as abdominal pain, nausea, and vomiting. Hypomotility is another concern. As castor oil increases gastrointestinal transition time, the intestine might get idle, which can lead to a decrease in gut motility.
Castor Oil’s Aid in Labor and Delivery
“Stimulation of movement” is another quality of Ricinus communis when it comes to promoting contractions in overdue pregnancies. Scientists of the Goethe Universität in Frankfurt am Main, Germany, were able to explain the mechanism of castor oil through research on mice—thereby clarifying that freed ricinoleic acid is absorbed through the intestinal mucosa, “then acts on EP3 receptors in the muscle cells in the intestines and uterus, thus stimulating intestinal and labor activity.”Castor oil has also proven effective in human studies.
A single dose of 60 milliliters (ml) of castor oil, in some trials mixed with fruit juice, was given to participating women in eight studies compiled in a 2022 review. Researchers looked into castor oil’s efficacy to induce labor in post-term pregnancies. The studies from Iran, Israel, and Nigeria concluded that the “oral administration of castor oil is effective for cervical ripening and labor induction.”
The recipe of these so-called “midwife’s brews” can change depending on the administrator. Another German study of the Universitäts-Frauenklinik Ulm employed the following mix: “20 ml castor oil, 20 ml almond butter, 10 ml sparkling wine, and 100 ml apricot juice.”
However, in all cases, the process should be monitored closely by a midwife or an obstetrician to ensure safe intervention.
Applications in the Course of Time and Place
Castor bean is of a tropical origin. Ancient traditional medicines in the Mediterranean and Eastern cultures utilized the castor plant for millennia. Ancient Egyptians and ancient Greek herbalists, including Hippocrates, all recognized the plant’s laxative action. It was used for the treatment of urinary diseases and detoxification—though mostly to cure ailments related to the digestive system.The ancient Indian medical system, Ayurveda, highlights the castor plant for gastrointestinal uses, as well as for inflammation, fever, skin disease, and lumbago.
Yunani, the traditional Perso-Arabic medicine, also recognizes these treatments and the historical Western medicinal treatment of applying a castor leaf to breasts to promote lactation.