The scientific, quasi-scientific and popular literature on the use of St. John's Wort in the treatment of depression.

St. John's Wort, also known as Hypericum, is an herbal product that is available in health food stores as an allegedly 'safe' alternative to antidepressants developed by the pharmaceutical industry. Recently it has received extensive coverage through the media, especially in the United States. To the best of our knowledge, Germany is the only country where it has been formally approved for clinical use. We reviewed both the vulgar and the scientific literature on this product. Although the few controlled studies that have been conducted pertain to adjustment disorder with depressed mood, several books and the media advocate its use for clinical and/or chronic depression. The high placebo rate in these studies, often in the 50% range, does indeed suggest that the controlled trials have been conducted on mild transient depressions; extrapolation to more serious or chronic depressions would therefore be unwarranted. We could not find any published literature comparing the efficacy of Hypericum to a standard antidepressant versus placebo. Furthermore, the studies claiming safety and freedom from potentially serious side effects appear flawed methodologically. Actually, little is known about the putative mechanism of action of Hypericum in depression; if indeed it does involve serotonergic mechanisms or monoamine-oxidase inhibition, it invites caution with concurrent use with an SSRI and, of course, with a MAOI. A skeptic might conclude that St. John's Wort should not be used until more definitive data are available. A less conservative view would be that, while its current widespread use is not warranted, the product may still have some merit for mild nonchronic depressive states below the clinical threshold. If this were conclusively proven, it would indeed constitute an important development in the field of antidepressants.