Therapies that lie outside the spectrum of traditional, science-based clinical medicine and surgery are often labeled as complementary or alternative. These therapies range from herbal remedies and dietary supplements to meditation and acupuncture, and they derive from Eastern and Western traditions. Use is widespread and often promoted by commercial interests and practitioners, with prevalence estimates exceeding 50%.1 Their popularity derives in part from being available without prescription and the supposition that the label of natural makes them safe and preferable to pharmacologic and surgical treatments.2 Despite widespread use, many complementary therapies still lack a rigorous evidence base.3