There is not enough evidence to support the use of evening primrose oil for any health condition.
According to a comprehensive 2013 evaluation of the evidence, evening primrose oil, taken orallyorallyto be taken by mouth (swallowed) (by mouth), is not helpful for relieving symptoms of eczema.
Evening primrose oil has been studied for rheumatoid arthritis and breast pain. However, study results are mixed, and most studies have been small and not well designed.
Evening primrose oil does not appear to affect menopausal symptoms.
The best-designed clinical trials of evening primrose oil for PMS found no effect.
Evening primrose oil is well tolerated by most people, when taken for short periods of time. Mild side effects include gastrointestinal upset and headache.
The safety of long-term use of evening primrose oil has not been established.
Evening primrose oil may increase bleeding in people who are taking the anticoagulant (blood thinning) medication warfarin.
Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.