Evening primrose is a plant that's native to Europe and North America. It has a long history of medicinal uses. For example, Native Americans used its leaves, roots, and seedpods in preparations for hemorrhoids, bruises, wounds, and skin problems.
Evening primrose oil contains an omega-6 essential fatty acid that is necessary for good health. While there is some evidence that evening primrose oil supplements may benefit some health conditions, the study results are mixed.