Evening Primrose Oil

Evidence from controlled clinical trials support the use of evening primrose oil (EPO) for the symptomatic treatment of atopic eczema, diabetic neuopathy and cycli- cal mastalgia. However, its therapeutic effects on rheumatoid arthritis, and premen- strual and menopausal symptoms have not been adequately demonstrated in clinical trials. Treatment with EPO should last at least 12 weeks before evaluating the thera- peutic response. The recommended daily dose is 320–480 mg (expressed as γ- linolenic acid) in divided doses for atopic eczema, and 240–320 mg (expressed as γ-linolenic acid) in divided doses for the treatment of mastalgia. Adverse reactions associated with the ingestion of evening primrose oil include headaches, nausea, soft stools and diarrhea. Oral administration of the seed oil may precipitate symptoms of undiagnosed temporal lobe epilepsy in schizophrenic patients taking epileptogenic drugs, such as the phenothiazines. Evening primrose oil has been shown to inhibit platelet aggregation in animal studies, and inhibits platelet-activating factor in human studies. While no drug interactions have been reported, patients taking other antico- agulant or antiplatelet drugs in conjunction with the seed oil should be closely mon- itored for bleeding times. In traditional medicine, evening primrose oil has been used as an emmenogogue and a method of inducing labor. While one clinical trial has indi- cated that EPO ingestion does not shorten gestation or decrease the overall length of labor, its administration was associated with an increase in the incidence of pro- longed rupture of membranes, oxytocin augmentation, arrest of decent and vacuum extraction. Therefore, evening primrose oil should be administered during pregnancy only on the advice of a physician.