Evening primrose oil comes from the seeds of the plant Oenothera biennis and is sometimes used for treating symptoms of premenstrual syndrome, or PMS, including menstrual cramps. Consult your doctor before taking evening primrose oil, however, to discuss potential health risks, drug interactions and proper dosage.
Besides relieving menstrual cramps and other PMS symptoms, evening primrose may help treat menopausal symptoms and fibrocystic breast disease, or mastalgia, according to the Memorial Sloan-Kettering Cancer Center. Additionally, you might take evening primrose oil for a wide variety of other health problems, including diabetes, eczema, rheumatoid arthritis, osteoporosis, alcoholism, cardiovascular diseases, multiple sclerosis, Raynaud’s disease, scleroderma, Sjogren’s syndrome or tardive dyskinesia, reports the University of Michigan Health System. Other uses for evening primrose oil include treating diabetic neuropathy, cancer and high cholesterol. No widely accepted clinical evidence supports any of these uses in humans, however.
Evening primrose oil contains the gamma-linolenic acid, or GLA, which your body converts into hormone-like substances called prostaglandins. Certain people have a tendency to be deficient in GLA, such as individuals with PMS, diabetes and certain skin conditions like eczema. You might want to take a GLA supplement like evening primrose oil if you have one of these conditions, but you should talk with your physician to determine whether GLA supplementation is right for you.
Suggested dosage is 3 to 6 g of evening primrose oil daily, standardized to contain 270 to 540 mg of GLA, according to the University of Michigan Health System. Unfortunately, medical researchers haven’t defined the exact dosage of evening primrose that’s suitable for treating PMS symptoms. Ask your doctor about the dosage that’s right for you before you begin taking evening primrose supplements.
A 1991 study published in the Journal of Nutrition Medicine found that women with breast diseases or PMS appear to be deficient in GLA and might benefit from taking evening primrose oil, notes the University of Michigan Health System. Several studies published in the journal Controlled Clinical Trials in 1996 found that taking evening primrose oil supplements helped to relieve PMS symptoms, according to the University of Pittsburgh Medical Center. Some of these medical studies were flawed, however, making the evidence weak.
The most commonly reported side effects of taking evening primrose oil are gastrointestinal upset and headaches. Evening primrose oil can increase your risk of pregnancy complications, so you shouldn’t use it if you’re pregnant or trying to become pregnant. UMHS reports that two cases published in 1981 and 1983 involved people who experienced worsened symptoms of temporal lobe epilepsy after taking evening primrose oil. Although no other cases of this complication have been reported, you should use evening primrose oil only under the close supervision of a doctor if you have a seizure disorder. Finally, evening primrose oil might interact with certain medications. If you take phenothiazines for seizures, anticoagulants or antiplatelets, you shouldn’t take evening primrose oil.