Evening primrose oil is the oil expressed from the seeds of the evening primrose plant, which grows wild in various parts of North America. This oil is very high in the essential fatty acid gamma-linolenic acid, which the body converts into prostaglandins.
Evening primrose oil is used in the manufacture of soaps and cosmetics to be used topically and is also available in capsule form to treat conditions, such as premenstrual syndrome and eczema. Studies have indicated that this supplement may also help reduce the pain of rheumatoid arthritis and benefit children diagnosed with attention deficit hyperactivity disorder. This oil is sometimes used to combat inflammation.