Major depression is a disorder characterized by a depressed mood and/or a loss of interest in nearly all activities consistently for at least 2 weeks. People with major depression may also experience a variety of other symptoms such as loss of appetite, fatigue, sleep disturbance, irritability, difficulty concentrating, and thoughts of death or suicide. Extracts from the herb St. John's wort (Hypericum perforatum) are used in many countries, especially Germany, to treat depression. However, results from clinical trials worldwide have been contradictory, and the effectiveness of St. John's wort for depression is still questionable. Additionally, major depression is often treated with antidepressant drugs, which have only shown modest effects over placebo in clinical trials.
NCCAM-funded researchers affiliated with universities in Germany reviewed the scientific literature on St. John's wort for major depression and analyzed findings from randomized, double-blind studies comparing St. John's wort extracts with placebo and standard antidepressants. The researchers reviewed a total of 29 studies in 5,489 people. The studies came from a variety of countries, tested several different St. John's wort extracts, and mainly included people with minor to moderately severe symptoms of depression.
According to this literature review, St. John's wort extracts appeared to be superior to placebo, were as effective as standard antidepressants, and had fewer side effects than antidepressants. However, the findings from studies in German-speaking countries were disproportionately favorable, possibly because some subjects had slightly different types of depression, or because some of the small studies were flawed and overly optimistic in reporting their results. The authors noted the need to investigate the reasons for the differences between study findings from German-speaking countries and those from other countries.
Linde K, Berner MM, Kriston L. St. John's wort for depression. Cochrane Database of Systematic Reviews.; (4):CD000448.2008