One hundred seventy-three patients with somatization disorder, undifferentiated somatoform disorder, or somatoform autonomic dysfunction, but not major depression, were randomly assigned to receive, in double-blind fashion, 300 mg of St. John's wort extract LI 160 twice a day or placebo for six weeks. Six outcome measures were evaluated as a combined measure by means of the Wei Lachin test: Somatoform Disorders Screening Instrument - 7 days, somatic subscore of the Hamilton Anxiety Scale, somatic subscore of the Symptom Check List 90 Revised, subscores "improvement" and "efficacy" of the Clinical Global Impression, and the global judgment of efficacy by the patient. In intent-to-treat analysis, for each of the six primary efficacy measures as well as for the combined test, St. John's wort was significantly more effective than placebo (p < 0.0001). Some 45.4% of the patients receiving St. John's wort were classified as responders, compared with 20.9% of those receiving placebo (p = 0.0006). Overall tolerability of St. John's wort was equivalent to that of placebo.

Comment: Somatoform disorders are characterized by chronic multiple physical symptoms that cannot be explained by any underlying disease condition. Patients with somatoform disorders remain convinced they are physically ill despite numerous negative medical evaluations. Patients with somatoform disorders spend an average of seven days per month in bed. The results of the present study demonstrate that administration of 300 mg of St. John's wort extract LI 160 twice a day is safe and effective in the treatment of somatoform disorders.

Muller T, et al. Treatment of somatoform disorders with St. John's wort: a randomized, double-blind and placebo-controlled trial. Psychosom Med 2004;66:538-547.