St. John's Wort Fact Sheet
Not regulated by the FDA, considered a dietary supplement.
Mechanism of psychiatric effect is unclear. Active antidepressant ingredients likely
- are hypericin and/or hyperforin. Both may inhibit the reuptake of serotonin, norepinephrine, and
- dopamine, but other neurochemical effects have been suggested as well.
Usual dose is 300 mg TID.
- • The standard preparation used to be 0.3% hypericin, but now manufacturers are offering
- products standardized to 2% to 6% hyperforin, since many believe hyperforin is the most
- important antidepressant component.
Assuming 900 mg QD, the cost is usually in the range of 50 cents to $1 per day.
Major Depression: About 30 randomized, double blind controlled trials have shown
- antidepressant efficacy, but most of these were published in European journals. U.S. trials
- have been mixed.
St. John’s Wort is a flowering herb (Hypericum perforatum) that blooms around
June 24 (St. John’s Day).
Rate of side effects similar to placebo and lower than standard antidepressants in
- controlled trials. Mild GI side effects and sedation are possible. Photosensitivity in fairskinned
- people. Switch to mania has been reported. No sexual side effects.
Probably induces the 3A4 isoenzyme of the P450 family of hepatic enzymes.
- • May decrease levels of the following drugs: cyclosporin (an immunosuppressive),
- indinavir (a protease inhibitor), warfarin, theophylline, digoxin, and oral contraceptives.
- • May cause serotonin syndrome in combination with SSRIs, but this is rare.
- • Little information is available on interaction with MAOIs, but most authorities
- recommend avoiding this combination.
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