Recommended doses of St. John’s wort range from 900–1800 mg/day, though different preparations may vary substantially due to standardization to different active ingredients, such as hypericin or hyperforin; head-to-head comparisons are, unfortunately, lacking. Tolerability is quite good, although adverse reactions have been documented, including potentially toxic adverse interactions with different medications. In particular, the combination of St. John’s wort with SSRIs has been shown to result in serotonin syndrome, a potentially fatal reaction. For this reason, patients should be cautioned not to combine St. John’s wort with SSRIs. The risk of interactions with other antidepressants is not clear, but overall St. John’s wort is best limited to monotherapy for depression.