In one study, women with moderate to severe premenstrual syndrome were treated with either a vitex agnus castus extract or a placebo for three menstrual cycles. (verywellhealth.com)
Agnus castus fruit extract was safe and effective for relieving symptoms of premenstrual syndrome (ebmh.bmj.com)
4 (1997): 183 - 189; Schellenberg R. «Treatment for the premenstrual syndrome with agnus castus fruit extract: propective, randomized, placebo - controlled study.» (saragottfriedmd.com)