St. John’s wort (SJW) is most commonly used to improve mood and treat depression. St. John’s wort affects neurotransmitters similar to conventional antidepressants. However, it also affects serotonin receptors in the gut, similar to irritable bowel syndrome (IBS) drugs such as alosetron (Lotronex).

Many IBS patients are now trying St. John’s wort. But new research is discouraging. It shows that taking a specific St. John’s wort extract (St. John’s Wort Extract Extra Strength, Enzymatic Therapy) 450 mg twice daily is no more effective than placebo for reducing symptoms after 12 weeks of treatment. In fact, some patients did worse on St. John’s wort compared to placebo.

The experts at the Natural Medicines Comprehensive Database tell physicians, “For now, explain to IBS patients that St. John’s wort doesn’t appear to be a good choice.”