Background: Extracts of the plant Hypericum perforatum L. (popularly called St. John's wort) have been used in folk medicine for a long time for a range of indications including depressive disorders.
Objectives: To investigate whether extracts of Hypericum are more effective than placebo and as effective as standard antidepressants in the treatment of depressive disorders in adults; and whether they have have less side effects than standard antidepressant drugs.
Search strategy: Trials were searched in computerized general (Medline, Embase, Psychlit, Psychindex) and specialized databases (Cochrane Complementary Medicine Field, Cochrane Depression & Neurosis CRG, Phytodok); by checking bibliographies of pertinent articles; and by contacting manufacturers and researchers.
Selection criteria: Trials were included if they: (1) were randomized; (2) included patients with depressive disorders; (3) compared preparations of St. John's wort (alone or in combination with other plant extracts) with placebo or other antidepressants; and (4) included clinical outcomes such as scales assessing depressive symptoms.
Data collection and analysis: Information on patients, interventions, outcomes and results was extracted by at least two independent reviewers using a standard form. The main outcome measure for comparing the effectiveness of Hypericum with placebo and standard antidepressants was the responder rate ratio (responder rate in treatment group/responder rate in control group). The main outcome measure for side effects was the number of patients reporting side effects.
Main results: 27 trials including a total of 2291 patients met inclusion criteria. 17 trials with 1168 patients were placebo-controlled (16 addressed single preparations, one a combination with four other plant extracts). Ten trials (eight single preparations, two combinations of hypericum and valeriana) with 1123 patients compared hypericum with other antidepressant or sedative drugs. Most trials were four to six weeks long. Participants usually had "neurotic depression" or "mild to moderate severe depressive disorders." Hypericum preparations were significantly superior to placebo (rate ratio 2.47; 95% confidence interval 1.69 to 3.61) and similarly effective as standard antidepressants (single preparations 1.01; 0.87 to 1.16, combinations 1.52; 0.78 to 2.94). The proportions of patients reporting side effects were 26.3% for hypericum single preparations vs. 44.7% for standard antidepressants (0.57; 0.47 to 0.69), and 14. 6% for combinations vs. 26.5% with amitriptyline or desipramine (0. 49; 0.23 to 1.04).
Reviewer's conclusions: There is evidence that extracts of hypericum are more effective than placebo for the short-term treatment of mild to moderately severe depressive disorders. The current evidence is inadequate to establish whether hypericum is as effective as other antidepressants. Further studies comparing hypericum with standard antidepressants in well defined groups of patients over longer observations periods, investigating long term side effects, and comparing different extracts and doses are needed.