Randomised trial, 2004
Does St. John's wort help with premenstrual symptoms?
There was a slight trend suggesting it might help, but the result was not statistically significant, so we cannot be sure it works.
What they did
169 women with recurrent premenstrual symptoms were recruited. After a baseline cycle, 125 women completed 2 treatment cycles with either 600 mg of St. John's wort or placebo. Symptoms were tracked daily in a menstrual diary, with anxiety-related symptoms as the primary measure.
What they found
St. John's wort showed a trend toward being better than placebo for anxiety-related symptoms, but this difference was not statistically significant. The authors noted this might be due to insufficient study size rather than the herb not working.
What it means for you
This study could not prove St. John's wort works, though a larger study might find an effect. The main limitation is that only 125 women completed the study, which may not be enough to detect a real benefit if one exists.
169
women recruited
125
women completed
600
mg dose per day
About the study
- Original title
- The significance of "nonsignificance" in randomized controlled studies: a discussion inspired by a double-blinded study on St. John's wort (Hypericum perforatum L.) for premenstrual symptoms
- Authors
- Hicks SM, Walker AF, Gallagher J et al.
- Journal
- Journal of alternative and complementary medicine (New York, N.Y.)
- Year
- 2004
- Study design
- Randomised trial
- What was tested
- 600 mg St. John's wort standardized to 1800 micrograms hypericin versus placebo for 2 menstrual cycles
- Read the paper
- doi.org/10.1089/acm.2004.10.925
Topics
Related studies
Guideline, 2024
How should Xiangshao Granules be prescribed for premenstrual tension syndrome?
Systematic review, 2021
Does damask rose help reduce menstrual pain, headache, fatigue, anxiety, and bloating?
Systematic review, 2008
What treatments work best for PMS and PMDD?
Randomised trial, 2025
Does Nigella sativa reduce PMS symptoms in women?
Review, 2023
Can herbs and supplements help with PMS symptoms?
Non-randomised trial, 2019
Does exercising before your period help with pain and anxiety?