In a double-blind trial patients with atopic eczema received either oral evening primrose oil (EPO) (n= 14) or placebo (n= 11) for 12 weeks. In the EPO group a statistically significant improvement was observed in the overall severity and grade of inflammation and in the percentage of the body surface involved by eczema as well as in dryness and itch. Patients in the placebo group showed a significant reduction in inflammation. The patients receiving EPO showed a significantly greater reduction in inflammation than those receiving placebo.

Evening primrose oil caused a significant rise in the amount of dihomogammatinolenic acid in the plasma phospholipid fatty acids. Plasma levels of TXB2, 6-keto-PGF1, and PGE1, and the amount of TXB2 released into serum during clotting were not altered by evening primrose oil.