Research shows that evening primrose oil improves nerve damage symptoms caused by diabetes, according to WebMD. It may also decrease bone loss and increase bone density in elderly individuals with osteoporosis when taken with fish oil and calcium. The oil is also a dietary source of essential fatty acids.
Evening primrose oil is often used to treat other health conditions for which research has not shown it to be effective, explains WebMD. Some of these conditions include heart disease, skin disorders, cancer, schizophrenia and multiple sclerosis. Some people also use evening primrose oil for gastrointestinal disorders, asthma, weight loss, chronic fatigue syndrome and whooping cough. Evening primrose oil is used by some women throughout pregnancy and for hormone-related conditions.