Researchers at the Institute of Psychological Sciences, University of Leeds, Leeds, UK gave 36 women with PMS aged 18-45 years St. John's wort tablets 900 mg/day for two menstrual cycles and compared the results to those taking placebo pills. The herb was statistically superior to placebo in improving physical and behavioral symptoms of PMS but there were no significant effects with the herb compared with placebo treatment for mood- and pain-related PMS symptoms.
Comments: I wonder if using one 300 mg St. John's wort pill in the morning and 50 mg of 5-HTP in late afternoon or evening would offer better results. See http://www.raysahelian.com/pms.html