EVENING PRIMROSE OIL Evening Primrose Oil (EPO) is an extract of the Evening Primrose flower. Evening Primrose Oil (EPO) contains Gamma Linolenic acid (GLA), an essential fatty acid that gets converted into a hormone-like substance called prostaglandin E1. Evening Primrose Oil is a tiny, short-lived, bright yellow wildflower native to North America. After discovering this New World plant, the Europeans took it back to the Old World where its healing properties for skin diseases and flesh wounds quickly earned it the name "King's Cure-All." Evening Primrose Oil is now grown in 30 or more countries, and the oil pressed from it's seed is marketed as a valuable natural healing supplement. It is especially well documented for supporting skin health in cases of eczema and dermatitis. But other benefits include relief of premenstrual syndrome and arthritis related joint pain.