In the United States, St John's wort is considered a dietary supplement by the FDA, and is not regulated by the same standards as a prescription drug. According to the United States National Center for Complementary and Integrative Health, "St. John’s wort isn’t consistently effective for depression"; they also note that it appears to be more effective than placebo and as effective as prescription SSRIs. Supplement strength varies by manufacturer and possibly by batch. With antidepressants, one "may have to try a few before finding what works best," notes the United States National Library of Medicine On average, lead levels in women taking St. John's wort are elevated about 20%.