Oenothera biennis (evening primrose) is a flowering plant that is native to North America. Indigenous tribes have been using this plant as a medicinal crop for hundreds of years, treating ailments such as bruises, hemorrhoids, digestive problems, and sore throats. Evening primrose seed extract is currently used in skin care products due to its high content of gamma-linoleic acid (GLA).
The GLA in evening primrose seed extract is thought to help skin conditions such as acne and eczema by reducing inflammation. In 2005, a randomized, double‐blind, placebo‐controlled study evaluated the effects of this extract on skin moisture, transepidermal water loss (TEWL), redness, firmness, elasticity, fatigue resistance, and roughness. The study found that the GLA in evening primrose seed extract is an essential fatty acid for the skin that is necessary for optimal structure and function.