Background Extracts of Hypericum perforatum (St John's wort) are widely used to treat depression. Evidence for its efficacy has been criticised on methodological grounds.

Aims To update evidence from randomised trials regarding the effectiveness of Hypericum extracts.

Methods We performed a systematic review and meta-analysis of 37 double-blind randomised controlled trials that compared clinical effects of Hypericum monopreparation with either placebo or a standard antidepressant in adults with depressive disorders.

Results Larger placebo-controlled trials restricted to patients with major depression showed only minor effects over placebo, while older and smaller trials not restricted to patients with major depression showed marked effects. Compared with standard antidepressants Hypericum extracts had similar effects.

Conclusions Current evidence regarding Hypericum extracts is inconsistent and confusing. In patients who meet criteria for major depression, several recent placebo-controlled trials suggest that Hypericum has minimal beneficial effects while other trials suggest that Hypericum and standard antidepressants have similar beneficial effects.

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