Hypericum is an herbaceous perennial weed used since the time of ancient Greece for its many medicinal properties (NIMH 1997; Bombardelli and Morazzoni 1994; Salzman 1998). The plant contains several chemical compounds thought to elevate mood; among them, hyperforin is regarded as the most likely source of this antidepressant action. It is believed that the herb achieves its effect by increasing levels of serotonin, an up (or excitatory) neurotransmitter, in the brain. Hypericum also may inhibit secretion of cortisol, a stress hormone (Wong et al, 1998; Chatterjee et al 1998). Data from clinical trials suggest that hypericum and prescription antidepressants may be equally effective in the treatment of mild-to-moderate depression (Linde et al 1996; Wheatley 1997; Hippius 1998). Moreover, the herb appears to be well tolerated (Hippius 1998), causing fewer side effects than those observed with conventional antidepressants (NIMH 1997; Wheatley 1997).
Only 2% to 3% of people who use hypericum experience side effects. The most common side effects are gastrointestinal problems, allergic reactions, fatigue, delayed hypersensitivity, dizziness, dry mouth, constipation, restlessness, and confusion. Because of these potential side effects, use of hypericum is not advised during pregnancy or lactation. In addition, users should avoid exposure to strong sunlight. Hypericum may interact with several important classes of antidepressant medications such as monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs). It is therefore important for depression sufferers to inform their physicians of all medications, herbs, and vitamin, mineral, and other nutritional supplements used so as to avoid harmful drug interactions.