There are many studies on St. John's wort, but they were all different. The National Center for Complementary and Integrative Health (NCCAM) under the National Institutes of Health (NIH), the most authoritative institution at present, has comprehensively analyzed many current studies on St. John's wort and summarized the results. Regarding the efficacy of St. John's wort, the following two conclusions are briefly presented:
St. John's wort
1. St. John's wort is not necessarily effective for depression. Note, not necessarily. So, don't use it as a substitute for evidence-based medicine, or put off seeking professional help.
2. The combination of St. John's wort and certain antidepressants may lead to a potentially fatal drug reaction, the main mechanism of which is the effect of serotonin (a neurotransmitter thought to be associated with depression or anxiety, etc.) increase rapidly.