Devotees claim that evening primrose oil can help with a host of ailments, from relatively minor problems such as eczema and menstrual distress to biggies like cancer and diabetes. But can it affect the progression of rheumatoid arthritis? And should you take evening primrose oil, usually sold as oral capsules, if you suffer from this condition?

The answer is "maybe." As with many facets of so-called alternative medicine, opinions differ. Evening primrose oil contains an omega-6 unsaturated fatty acid known as gamma linoleic acid, or GLA. The body uses GLA to make prostaglandins, hormones that supposedly help regulate the immune system. In theory, this would help people fight rheumatoid arthritis, an autoimmune disease. But does it?

Unfortunately, study results are mixed. One promising study of 56 arthritis patients showed that those who received GLA over a six-month period had significant reductions in joint pain, stiffness, and strength, while other studies have found no correlation between GLA and rheumatoid arthritis.

Is there any danger to trying evening primrose oil as an arthritis therapy? Probably not, although it can have side effects. It may worsen epilepsy and should be avoided by people on anti-seizure medication. It also may cause inflammation, depressed immune system, or blood clots if taken for very long periods. And pregnant or nursing women would do well to exercise caution. Be sure to check with your health-care provider before embarking on a course of treatment with evening primrose oil or any plant or herb extract touted as a miracle cure.


National Center for Complementary and Alternative Medicine,

University of Maryland Medical Center,

American Cancer Society,