. . . evening primrose oil (also known as EPO) is a nutritional supplement that is frequently mentioned. In his book, "Solved: The Riddle of Illness," Stephen Langer, M.D. points to the fact that symptoms of essential fatty acid insufficiency are very similar to hypothyroidism, and recommends evening primrose oil -- an excellent source of essential fatty acids -- as helpful for people with hypothyroidism. The usefulness of evening primrose oil, particularly in dealing with the issues of excess hair loss with hypothyroidism, was also reinforced by endocrinologist Kenneth Blanchard. According to Dr. Blanchard:
"For hair loss, I routinely recommend multiple vitamins, and especially evening primrose oil. If there's any sex pattern to it -- if a woman is losing hair in partly a male pattern - -then, the problem is there is excessive conversion of testosterone to dihydrotestosterone at the level of the hair follicle. Evening primrose oil is an inhibitor of that conversion. So almost anybody with hair loss probably will benefit from evening primrose oil."
As someone who has had a few periods of extensive hair loss since I became hypothyroid, I can vouch for the fact that taking EPO was the only thing that calmed it down. It not only slowed, then stopped my hair loss over about two months, but new hair grew back, and my hair was no longer straw-like, dry and easily knotted.