One of the oils found in evening primrose seeds is Gamma-Linolenic Acid (GLA) which is frequently recommended by practitioners for those: at the time of their period, going through the menopause or concerned with the condition of their skin.
Deficiency of essential fatty acids has been reported in women with PMS. Gamma-Linoleic Acid is converted into prostaglandins - hormone like substances - that control a variety of physiological functions including hormone production and nerve transmission, both particularly relevant with PMS. GLA from evening primrose oil has been shown to improve many substances including pre-menstrual headaches, anxiety and bloating.
One to three capsules daily.