Is evening primrose oil of value in the treatment of premenstrual syndrome?

A systematic literature search of clinical trials of evening primrose oil (EPO) for the treatment of the premenstrual syndrome (PMS) was carried out with a view to performing a meta-analysis. Only seven placebo-controlled trials were found but only in five trials was randomization clearly indicated. Inconsistent scoring and response criteria made statistical pooling and hence a rigorous meta-analysis inappropriate. The two most well-controlled studies failed to show any beneficial effects for EPO, although because the trials were relatively small modest effects cannot be excluded. Nonetheless, on current evidence EPO is of little value in the management of premenstrual syndrome.