The results of trials have been good, with upwards of 60% of women with PMS (premenstrual syndrome) improving on evening primrose oil.
The most recent scientific trial (1985-1987) on evening primrose oil and PMS was at the Royal Free Hospital and St Thomas’s Hospital in London. There has also been a recent study on PMS at the Universities of Helsinki and Oulu in Finland.
The Royal Free and St Thomas’s trial involved 60 women with PMS in a double-blind, placebo-controlled trial, which assessed the effects of evening primrose oil compared with a placebo on the six common symptoms of PMS – depression, irritability, breast pain, clumsiness, bloating, and headache.
The results showed that all the six symptoms improved considerably. Overall, 60% improved on evening primrose oil (Efamol), compared with only 30% who took the placebo.
The Royal Free trial did not include any vitamins, minerals, dietary or lifestyle recommendations. The response rate is likely to increase if these are included.
In Sweden, evening primrose oil has had very good results on a wide range of PMS symptoms.
During 1981, a study was done at one of the major PMS clinics in the UK, at St Thomas’s Hospital in London.  In this study, 65 women with bad PMS were treated with evening primrose oil (Efamol). All of them had tried one or more other standard treatment, and all of them had failed.
The results were good, with 61% of the women experiencing complete relief of their symptoms, and 23% partial relief. The other 15% said there had been no change as a result of taking evening primrose oil.
One particular symptom – breast discomfort – was helped considerably, with 72% saying this had improved. Other common symptoms that showed improvement after taking evening primrose oil were mood swings, anxiety, irritability, headaches, and fluid retention.
In the Finnish study it was found that Efamol particularly helped in relieving depression in the pre-menstrual syndrome.
Dr Michael Brush, the biochemist who did the St Thomas’s study, liked the idea of using a natural product with a nutritional approach as many of the drugs for PMS can have undesirable side effects.
In almost all cases, the starting dose was two capsules twice a day after food. Although a few patients were given treatment all through their menstrual cycle, most of them started treatment three days before the symptoms were expected to arrive and carried on until the start of their period. In a few very severe cases, the dose was increased to three capsules twice a day. Some of the patients were given Vitamin B6 (pyridoxine) at the same time.

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WOMEN’S HEALTH