St. John’s wort has had a mixed success rate in clinical trials, and the latest news does not help the yellow flower.

According to a June 10, 2008 study published in JAMA, St. John’s wort does not appear to improve the symptoms of attention-deficit/hyperactivity disorder (ADHD) in children and teens in comparison with a placebo.
Hypericum perforatum, also called St. John’s wort, is one of the CAM therapies used for depression. To investigate St. John’s wort as a remedy for the symptoms of ADHD, Wendy Weber, N.D., Ph.D., M.P.H., of Bastyr University, Kenmore, Wash., and colleagues performed a trial of 54 children and adolescents with ADHD between the ages of 6 and 17 years. Of these, 27 subjects were randomly assigned to receive 300mg of H. perforatum standardized to 0.3% hypercin, while the other 27 received a matched placebo. Treatment was administered three times daily for eight weeks while all other ADHD medications were forbidden.
No significant discrepancy was found between the two groups in terms of ADHD rating scale scores related to inattentiveness and hyperactivity in any of the 8 weeks of trials. There was also no difference found in the proportion of participants rated either much or very much improved in relation to ADHD symptoms on a second, different measurement scale called the Clinical Global Impression Improvement Scale. Finally, no statistically significant difference was found between the two groups for adverse events, including rash, nausea/vomiting, headache, or sunburn.
ing the trial.
“To our knowledge, this is the first placebo-controlled trial of H. perforatum in children and adolescents. The results of this study suggest that administration of H. perforatum has no additional benefit beyond that of placebo for treating symptoms of child and adolescent ADHD.”
The study by Weber et al. is: “Hypericum perforatum (St John’s Wort) for Attention-Deficit/Hyperactivity Disorder in Children and Adolescents: A Randomized Controlled Trial.”
Previously there had been some studies showing success of St. John’s wort for mild to moderate (but not severe) depression, although the studies on use for moderate depression were later challenged.
I once worked with a law partner who kept a bottle in his desk (St. John’s wort, not whiskey), and that seemed like a good enough claim of efficacy for some of the other folks in the firm who preferred personal recommendation to placebo-controlled studies.