Evening primrose oil is a supplement that has been used for hundreds of years. The oil comes from the seeds of evening primrose. Evening primrose is a plant native to North and South America that now also grows in Europe and parts of Asia. The plant blooms from June to September, producing large, yellow flowers that only open in the evening. The oil that comes from evening primrose’s seeds has omega-6 fatty acids. Evening primrose oil is used for a variety of reasons, including in the management of eczema and menopause. Evening primrose oil is also referred to as king’s cure-all and EPO.