It may not exactly be a household name, but evening primrose, a bright yellow plant native to North America, has a large following in the alternative medicine world.
The seeds of the plant contain essential fatty acids, which are used to make an oil that has a variety of uses as a dietary supplement and folk remedy. Its most popular use may be for eczema, the skin condition that affects as many as one in five people. Widely marketed and easy to find, primrose oil contains gamma linolenic acid, which is thought to help reduce skin inflammation without the side effects of other treatments.
But a large new study suggests that people using evening primrose oil for eczema may want to save their money.
In the study, a review of evidence published in The Cochrane Library, researchers looked at data from 27 studies involving either evening primrose oil or a similar supplement, borage oil, which is also rich in gamma linolenic acid. The studies, which included about 1,600 adults and children, compared the supplements with a placebo.
The researchers did not find that taking either evening primrose or borage allayed eczema any more than taking dummy pills. But they did find a potential risk.
Evening primrose oil can have anti-coagulant effects that increase the risk of bleeding, something that is especially dangerous for people already taking blood-thinning drugs like warfarin.