Castor oil comes from the seeds of the castor bean plant, Ricinus communis. It is a pale yellow liquid with a distinctive taste and odor, and is composed mainly of ricinoleic acid, accounting for about 90% of the fatty acid content.
Known for its many industrial, medical and cosmetic uses, castor oil has been used for centuries. Industrially, castor oil is used as a lubricant and is used to produce soaps, paints, inks and waxes. Medically, it is often used as a laxative to relieve constipation. Researchers at the University of Auckland in New Zealand have also tested castor oil for the treatment of dry eye disease, with promising results.
Dry eye syndrome, increasing in both young and old
Dry eye syndrome, also known as keratoconjunctivitis, is a common condition that occurs when the eyes do not produce enough tears or when tears evaporate too quickly. This causes inflammation and damage to the surface of the eye, causing discomfort and vision problems.
In certain regions worldwide, prevalence rates can reach up to 50%.One The risk increases after age 50. Other risk factors include menopause, autoimmune diseases, prolonged screen time, and contact lens wear.
In New Zealand, it is estimated that 58% of people over 50 years of age have dry skin.2 For example, in the United States, the condition is on the rise among both younger and older adults, and the American Academy of Ophthalmology notes that “it is imperative that clinicians learn how to best treat it.”three
Blepharitis, an inflammation of the eyelids, particularly underneath the eyelashes, is one of the most common causes of dry eye, accounting for more than 80 percent of all cases, according to the University of Auckland.4
“Patients currently experience symptoms of dryness, grit, and in some cases, watery eyes, which can be uncomfortable and impact their quality of life and work productivity,” explained Catherine Jennings, the study’s lead clinical researcher. “Patients often feel helpless when trying to manage their chronic condition.”5
Antibacterial and anti-inflammatory drugs can be used as a treatment, but they are not suitable for long-term use due to antibacterial resistance and serious side effects. Instead, researchers at the University of Auckland tested cold-pressed castor oil, fortified with manuka and kanuka oils, using a rollerball applicator as a treatment.
Studies have shown that castor oil is effective in treating blepharitis and dry eye.
The study involved 26 people with blepharitis symptoms. They applied a 100% cold-pressed castor oil formulation to the eyelid of one eye twice a day for four weeks.6
Initially, there was no difference between the treated and control eyes. However, after four weeks of treatment, the dry eye symptoms in the eyes treated with castor oil significantly improved. The treated eyes showed less eyelid swelling, less visible blood vessels, less tangled eyelashes, less eyelash loss, less dandruff-like dandruff, and less eyelid inflammation.
Castor oil treatment also resulted in fewer staphylococci and seborrheic lesions on the eyelashes compared to control eyes. Additionally, no negative side effects were reported. According to the study:7
“Topical castor oil application resulted in significant improvements in ocular surface signs and symptoms in patients with blepharitis. The favorable therapeutic profile suggests that castor oil holds promise as a potential treatment for blepharitis and supports the conduct of additional efficacy trials with longer follow-up.”
The researchers are currently conducting a double-blind, randomized, placebo-controlled study to further explore the effects of castor oil on dry eyes and eyelash crusts.8 Jennifer Craig, director of the Ocular Surface Laboratory at the University of Auckland and study author, said:9
“Castor oil has been proposed as a natural product that may provide a safe, effective, and easy-to-use alternative to conventional treatments.
My hope is that this study will provide evidence-based guidance for clinicians to offer castor oil as a possible management option for their patients suffering from blepharitis, so that they can continue to enjoy a good quality of life, read their favorite books, be productive in their work environment, and enjoy other visual hobbies.”
Craig and colleagues, in a 2020 review of the therapeutic potential of castor oil in the management of blepharitis, dry eye, and macular edema (MGD), a condition that causes dry eye, noted:10
“Caster oil is considered safe and well-tolerated and has potent antibacterial, anti-inflammatory, analgesic, antioxidant, wound healing and vasoconstrictor properties. The main component, ricinoleic acid, has a bipolar molecular structure that promotes the formation of esters, amides and polymers.
They can supplement the deficient physiological tear film lipids, enhance lipid diffusion properties, and reduce aqueous tear evaporation. Studies have shown that topically applied castor oil on the ocular surface has a long residence time, increases tear film lipid layer thickness, stability, improves ocular surface pigmentation, and improves symptoms.”
Topical castor oil has a variety of uses.
Castor oil is considered one of the world's oldest drugs and is perhaps best known for its laxative effects and ability to induce labor in pregnant women.11 — However, we do not recommend using it for the latter purpose.
When applied topically, castor oil can help reduce inflammation and fight infections. It is also used to treat conditions such as arthritis and minor skin infections, and the oil can promote healing of minor cuts and abrasions due to its antibacterial properties.
“Our previous pilot study using castor oil applied to the eyelids in this way was unique, as it is not known to have been used anywhere in the world to treat blepharitis,” Jennings said.12 However, anecdotal reports suggest that applying a small amount of castor oil to the eyelids may help you fall asleep, and topical castor oil is widely used for a variety of hair and skin care purposes.
Castor oil has a variety of cosmetic uses and is a popular ingredient in skin care products due to its ability to deeply moisturize and hydrate the skin. It is often used to treat dry skin and conditions such as eczema and psoriasis, and is also used in hair care products to support hair growth, reduce dandruff, and moisturize the scalp.13
Massaging your scalp (and eyebrows) with warm castor oil can stimulate hair follicles and help hair grow more. Do this every night and you should see improvements in just two weeks. Castor oil can also be beneficial for areas affected by hair loss.
In addition to providing moisture to the hair, the fatty acids in castor oil can also provide nutrition to the hair follicles. Ricinoleic acid also helps protect the scalp and hair shaft from fungal and microbial infections. It can also inhibit prostaglandin D2 synthase, which penetrates the skin and inhibits hair growth.14
Castor Oil for Skin Care and Fungal Infections
Some people also use castor oil to reduce the appearance of wrinkles and fine lines due to its moisturizing and anti-inflammatory properties. The fatty acids in castor oil help nourish and moisturize dry skin. It has a viscous consistency that stays put and easily penetrates into skin tissue. Castor oil is considered an occlusive moisturizer, which forms a barrier on the skin to prevent moisture evaporation.15
The antibacterial and anti-inflammatory properties of castor oil may also have beneficial effects on skin tags, acne, and warts. A study published in the Journal of International Toxicology found that castor oil may also have a positive effect on occupational dermatitis.16
Castor oil may also be useful in relieving common infections such as tinea versicolor, groin itch (ringworm), and athlete's foot. Studies have shown that phytochemicals in castor essential oil can relieve infections caused by the fungus Cunninghamella bertholletiae and standard antifungal medications.17
To use, simply rub a teaspoon of castor oil between your palms and apply it to your skin. You can also mix castor oil 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 considered “generally safe and effective” for use as a stimulant laxative.18 According to the U.S. Food and Drug Administration, taking castor oil orally can “cleanse” your digestive tract within two to five hours.
However, you should take the appropriate dosage. Adults can take 1-2 tablespoons, while children between 2 and 12 years old should take only 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 with freshly squeezed juice to make it more delicious.
Topical application of ricinoleic acid, found in castor oil, may also have “remarkable analgesic and anti-inflammatory effects.”19 It is effective in relieving muscle pain, joint pain, and “may serve as an effective treatment” for patients with knee osteoarthritis.20
Castor oil can be rubbed into muscles after exercise to promote 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 collects waste from tissues and carries it to the bloodstream for removal. Castor oil applied topically to the skin can help activate the lymphatic system.
Is castor oil toxic?
Castor beans have notable anti-inflammatory, anti-parasitic, anti-bacterial, wound healing and laxative properties, but they also contain ricin, a poison that can inhibit protein synthesis in cells and lead to cell death. This is why chewing and swallowing castor beans is toxic. Ricin is also present in the pulp of the beans left after the oil is extracted, but castor oil does not contain ricin.
According to the International Journal of Toxicology, “Castor oil does not contain ricin because ricin is not distributed in castor oil.”21 The longest-used one may be castor bean. According to Toxins reviews:22
“Castor beans have been known since ancient times, and their use in prehistoric times is evidenced by archaeological finds, such as the Border Cave in South Africa. Wax traces containing ricinoleic and ricinoleic acids have been found on thin wooden sticks, believed to have been poison application tools dating back about 24,000 years.”
Ricin interferes with protein synthesis and kills cells when taken orally, nasally, or intravenously. It is so potent that ingesting or inhaling just one milligram can be fatal.23 It's like eating 4 to 8 castor beans can lead to death.24 Since ricin has no antidote, it is also used in chemical warfare.25
How to Use Castor Oil Safely
Castor oil is safe at recommended doses, although castor beans are highly toxic. However, large doses can lead to serious gastrointestinal upset, including severe diarrhea and dehydration. Overdosing can also upset electrolyte balance, so it is important to follow the recommended dose for internal use and test your skin for sensitivity before applying topically.
Also, pregnant women should not use castor oil because of its ability to induce contractions. It is not recommended to use castor oil to stimulate labor even in late pregnancy. One study reported that all pregnant women who took castor oil experienced nausea afterwards.26
Another study warned that castor oil-induced contractions may cause the fetus to pass meconium (the baby's first stool) while still in the womb, putting the newborn at risk for meconium aspiration, which can lead to respiratory distress.27
If you have digestive problems such as irritable bowel syndrome, ulcers, cramps, diverticulitis, colitis, or hemorrhoids, you should avoid using this oil. People who have recently undergone surgery should also avoid using castor oil. And when choosing a product to use, look for organic castor oil from a trusted source.
Many commercial castor oils contain pesticide residues and are treated with solvents and other chemicals. If you want the highest quality oil with no contaminants and all the beneficial properties, look for organic castor oil.
