Castor oil is obtained from the seeds of the castor bean (Ricinus communis). It is a pale yellow liquid with a distinctive taste and aroma, composed mainly of ricinoleic acid, which accounts for about 90% of the fatty acid content.
Castor oil has been known for a variety of industrial, medical, and cosmetic uses and has been utilized for centuries. Industrially, castor oil is used as a lubricant and in the manufacture of soaps, paints, inks, and waxes. Medicinally, it is often used as a laxative to relieve constipation. Researchers at the University of Auckland in New Zealand have also tested castor oil to treat dry eyes with promising results.
Dry eye syndrome is on the rise among people of all ages and genders
Dry eye disease, also known as dry eye syndrome or keratoconjunctivitis sicca, is a common condition that occurs when the eyes do not produce enough tears or the tears evaporate too quickly, resulting in inflammation and damage to the ocular surface, causing discomfort and vision loss.
Globally, the prevalence rate in certain regions is as high as 50%,1 The risk increases in people over 50. Other risk factors include menopause, autoimmune diseases, excessive screen time and wearing contact lenses.
In New Zealand, it is estimated that 58% of people aged 50 and over suffer from dry eye.2 For example, the condition is on the rise in both young and older people in the United States, “making it urgent for clinicians to identify the best ways to treat it,” according to the American Academy of Ophthalmology.3
Blepharitis, which causes inflammation of the eyelids, especially the base of the eyelashes, is one of the most common causes of dry eye, accounting for more than 80 percent of cases, according to the University of Auckland.Four
“Patients currently suffer from symptoms such as dry, gritty and sometimes watery eyes, which negatively impact their quality of life and work productivity,” explained Katherine Jennings, lead clinical researcher on the study. “They often feel helpless when trying to manage their chronic symptoms.”Five
While antibiotics and anti-inflammatory drugs are available for treatment, antibiotic resistance and serious side effects make them unsuitable for long-term use. Instead, researchers at the University of Auckland used cold-pressed castor oil spiked with manuka and kanuka oils, applied with a rollerball applicator.
Research shows castor oil is effective against blepharitis and dry eyes
The study involved 26 people with signs of blepharitis who applied a 100% cold-pressed castor oil formulation to the eyelid of one eye twice daily for four weeks.6
At the start of treatment, there was no difference between treated and control eyes. However, after four weeks of treatment, dry eye symptoms improved significantly in eyes treated with castor oil. Treated eyes showed less eyelid swelling, visible blood vessels, tangled eyelashes, eyelash loss, flaking, and eyelid inflammation.
Castor oil treatment also reduced staphylococcal and seborrheic crusts on the eyelashes compared to the control group eyes. Additionally, no side effects were reported. According to the study,7
“Topical castor oil application produced significant improvement in ocular surface signs and symptoms in patients with blepharitis. The favorable treatment profile suggests that castor oil holds promise as a potential treatment for blepharitis and supports further efficacy studies with longer follow-up.”
The researchers are currently conducting a double-blind, randomized, placebo-controlled trial to further examine the effects of castor oil on dry eye and eyelash crusting.8 “This is a very interesting study,” said study author Jennifer Craig, director of the Ocular Surface Institute at the University of Auckland.9
“Castor oil has been proposed as a natural product that may be a safe, effective and easy-to-use alternative to existing treatments.”
“We hope that this study will provide evidence-based guidance to clinicians on offering castor oil as a treatment option to patients suffering from blepharitis, allowing them to continue to enjoy a high quality of life, read their favorite books, stay productive in their work environment, and enjoy other visual hobbies.”
In 2020, Craig and colleagues wrote a review on the therapeutic effects of castor oil in managing meibomian gland dysfunction (MGD), which causes blepharitis, dry eye, and even dry eyes, stating:Ten
“Castor oil is considered safe and well tolerated and has potent antibacterial, anti-inflammatory, anti-pain, analgesic, antioxidant, wound healing and vasoconstrictor properties. Its main component, ricinoleic acid, has a dipolar molecular structure that promotes the formation of esters, amides and polymers.”
They can replenish the physiological tear lipids that are insufficient, enhance the lipid spreading properties, and reduce the evaporation of aqueous tears. Research has shown that castor oil applied topically to the ocular surface increases the residence time, thickness and stability of the tear lipid layer, and improves ocular surface staining and symptoms.
Topical castor oil has many uses
Castor oil is thought to be one of the world’s oldest medicines and is perhaps best known for its laxative effects and its ability to induce labor in pregnant women.11 However, using it for the latter purpose is not recommended.
When applied topically, castor oil may help reduce inflammation and fight infection. It’s also sometimes used to treat conditions like arthritis and minor skin infections, and its antibacterial properties can promote the healing of minor cuts and scrapes.
“A previous pilot study conducted by our research team found that applying castor oil to the eyelids in this way was unique, and this product is not known to be used anywhere in the world to treat blepharitis,” Jennings said.12 However, some anecdotal reports suggest that rubbing a small amount of castor oil on the eyelids can help people fall asleep more easily, and topical castor oil is commonly used for a variety of hair and skin care purposes.
Castor oil has a wide variety of cosmetic uses and is a popular ingredient in skin care products due to its deeply moisturizing effects. It is often used to treat conditions such as dry skin, eczema and psoriasis, and in hair care products it is used to promote hair growth, reduce dandruff and moisturize the scalp.13
Massaging warm castor oil into your scalp (and eyebrows) may stimulate hair follicles and promote hair growth. Do this nightly and you may see improvement in just two weeks. Castor oil may also be effective in areas affected by hair loss.
The fatty acids in castor oil may not only moisturize hair but also nourish hair follicles. Ricinoleic acid also helps protect the scalp and hair shaft from fungal and microbial infections. It may also penetrate the skin and inhibit prostaglandin D2 synthesis enzymes, which inhibit hair growth.14
Castor Oil for Skin Care and Fungal Infections
Some people use castor oil to reduce the appearance of wrinkles and fine lines because of its moisturizing and anti-inflammatory properties. The fatty acids in castor oil nourish and hydrate dry skin. Its viscous properties allow it to stay on the skin and penetrate the skin tissue easily. Castor oil is considered an occlusive moisturizer, which means it forms a barrier on the skin to prevent moisture from evaporating.15
Castor oil’s antibacterial and anti-inflammatory properties may also have beneficial effects on skin tags, acne, and warts. A study published in the International Journal of Toxicology also found that castor oil may have beneficial effects on occupational dermatitis.16
Castor oil may also help relieve common infections such as ringworm, tinea cruris, and athlete’s foot. Research also suggests that the phytochemicals in castor oil may not only ward off standard antifungal medications, but also infections caused by the fungus Cunninghamella bertholletiae.17
To use it, simply rub a teaspoon of castor oil between your hands and apply it to your skin. You can also mix it with a carrier oil to reduce the risk of irritation.
What else is castor oil good for?
If you need a natural laxative, castor oil is “generally considered safe and effective” as a stimulant laxative.18 According to the U.S. Food and Drug Administration, when taken orally, castor oil can “cleanse” the digestive tract within two to five hours.
However, remember to take the right amount: adults should only give 1-2 tablespoons and children aged 2-12 years old 1-2 teaspoons. Infants under 2 years old are not recommended to take more than 1 teaspoon at a time. When giving it to children, try mixing it in freshly squeezed juice to make it more palatable.
When applied topically, the ricinoleic acid found in castor oil may also have “significant analgesic and anti-inflammatory effects.”19 This helps relieve muscle and joint pain and “can be used as an effective treatment” for patients with knee osteoarthritis.20
Castor oil can be applied to muscles after exercise to increase circulation and relieve pain, or massaged into joints to relieve pain. The ricinoleic acid in castor oil also has a decongestant effect on the lymphatic system, which is responsible for collecting waste products from tissues and transporting them to the bloodstream for removal. Applying castor oil topically to the skin may help stimulate the lymphatic system.
Is castor oil toxic?
Although castor beans have anti-inflammatory, anthelmintic, antibacterial, wound-healing and laxative properties, they also contain a toxin called ricin, which inhibits protein synthesis in cells and causes cell death. This is what makes castor beans toxic if chewed or swallowed. Ricin is also found in the pulp of the beans that remains after the oil is extracted, but castor oil does not contain ricin.
According to the International Journal of Toxicology, “Ricin does not partition into castor oil, so castor oil does not contain ricin.”twenty one Perhaps the most long-standing poison is castor bean poison. According to a review in Toxins:twenty two
“The castor plant has been known since ancient times and archaeological finds such as the Border Caves in South Africa attest to its prehistoric use. Traces of wax containing ricinoleic and ricineric acids have been found on thin wooden sticks that may have been poison applicators dating back around 24,000 years.”
Ricin inhibits protein synthesis and kills cells when administered orally, intranasally, or intravenously, and is so potent that ingesting or inhaling just one milligram can be fatal.twenty three Just like eating 4 to 8 castor seeds can be deadly.twenty four Ricin has no antidote, so it is also used as a chemical weapon.twenty five
How to Use Castor Oil Safely
While castor beans are highly toxic, castor oil is safe at recommended doses. However, if taken in large quantities, it can cause serious gastrointestinal problems, including severe diarrhea and dehydration. Overdosing can also upset electrolyte balance, so it’s important to follow recommended doses if taking it internally and test skin sensitivity before applying topically.
Additionally, pregnant women should not use castor oil because it can induce labor. It is not recommended to use castor oil to induce labor, even in the later stages of pregnancy. In one study, all pregnant women who took castor oil experienced nausea afterward.26
Other studies have warned that castor oil contractions may cause the fetus to pass meconium (a baby’s first stool) while in the womb, putting the baby at risk of meconium aspiration, which can cause newborns to have respiratory distress.27
It is recommended that you avoid using this oil if you suffer from digestive problems such as irritable bowel syndrome, ulcers, cramps, diverticulitis, colitis, hemorrhoids, etc. People who have recently had surgery should also refrain from using castor oil. When choosing products to use, look for organic castor oil from a trusted source.
Much of the castor oil on the market contains pesticide residues and has been treated with solvents and other chemicals. For the highest quality oil, free of contaminants and with its beneficial properties intact, look for organic castor oil.
