Medical Today

General use

Internal uses

Castor oil is a strong and effective cathartic or purgative (laxative), with components in the oil that affect both the small and large intestines. It has been used to clear the bowels after food poisoning and to relieve constipation.

It is sometimes used in hospitals to prepare the patient’s abdomen for x rays of the colon or kidneys. Castor oil is classified as a stimulant laxative, also known as a contact laxative. This type of laxative encourages bowel movements by acting on the intestinal wall, increasing the muscle contractions that move along the stool mass.

Stimulants are a popular type of laxative for self-treatment, but unfortunately are more likely to cause side effects.

There are milder types of laxatives that may be more useful for inducing regularity and treating constipation.

Generally laxatives should be used to provide short term relief only, unless otherwise directed by a doctor.

Castor oil is frequently used in animal experiments to test the effects of new medications on the gastrointestinal tract.

If castor oil has been prescribed by a doctor, his or her instructions for the timing and quantity of doses should be followed. For self-treatment, users should follow the manufacturer’s instructions. At least 6–8 glasses (8 oz each) of liquids should be taken each day to soften the stools. Castor oil is usually taken on an empty stomach for rapid effect. Because results usually occur within two to six hours, castor oil is not usually taken late in the day. The unpleasant taste of castor oil may be improved by chilling it in the refrigerator for at least an hour. It may then be stirred into a glass of cold orange juice. Flavored preparations of castor oil are also available.

External uses

Castor oil is also used topically to treat corns. The oil is applied once or twice daily directly to the corns, which are surrounded with adhesive-backed corn aperture pads made of felt to hold the oil. The corns are then covered with hypoallergenic silk tape. After soaking with the castor oil, the corns will be softened for removal with a pumice stone. Castor oil can be used in a similar manner to remove warts. Castor oil is also used to treat ringworm, abscesses, bruises, dry skin, dermatitis, sunburn, open sores, and other skin conditions. Additional less well-known uses of castor oil include hair tonics, cosmetics, and contraceptive creams and jellies.

For menstrual cramping, especially when fibroids may be present or when flows are heavy, castor oil packs may be placed on the abdomen for up to an hour. The packs are made by soaking square or rectangular pieces of cotton, cotton flannel, or undyed wool 2–4 in (5–10 cm) thick with 4–6 oz 118–177 ml) of castor oil. The pack is folded over once or twice, placed directly on the abdomen, and covered with plastic wrap. Over the pack, a water bottle or a heating pad on a low setting may be used to keep the pack warm. After use, the skin may be cleansed with a warm solution of baking soda and water (2 tsp of baking soda to 1 qt water). Some herbal therapists maintain that castor oil packs may aid in shrinking small fibroids. Castor oil packs have also been used in the treatment of many other diseases and disorders, including breast pain, digestive tract problems, abscesses, hemorrhoids, wounds, and gallstones.

Nonmedical uses

Castor oil and its derivatives also are used in many industrial products, including paint and varnish, fabric coatings and protective coverings, insulation, food containers, soap, ink, plastics, brake fluids, insecticidal oils, and guns. It is a primary raw material for the production of nylon and other synthetic resins and fibers, and a basic ingredient in racing motor oil for high-performance automobile and motorcycle engines. Castor oil is also used as a fuel additive for two-cycle engines, imparting a distinctive aroma to their exhaust. Even though it is malodorous and distasteful, it is the source of several synthetic flower scents and fruit flavors.