Is St John’s wort effective?

I recently saw Rhys, a 29-year-old graphic designer suffering from an adjustment disorder with depressed mood, following the separation from his partner

 He mentioned an interest in St John’s wort and wanted my advice. I knew that there was some supportive evidence for its use in major depressive disorder,1 but what about in the ‘minor’ depressive disorders commonly seen in general practice?

Clinical question

What is the effect of St John’s wort on depressive symptoms in depressive disorders that do not meet the DSM criteria for major depressive disorder?

What does the research evidence say?

Step 1: The Cochrane Library

The Cochrane Library contains a 2008 systematic review that examines St John’s wort for major depression only, though most study participants had “mild to moderate” symptoms. 1