Dangerous Interactions with St. John's Wort
St. John’s Wort is the most common herbal treatment used for depression. Unfortunately, because of the way in which herbs are regulated an marketed, many people do not understand that herbal treatments are drugs. A study recently published in the Journal of Complementary and Alternative Medicine found that 28% of subjects prescribed St. John’s Wort for depression were also taking drugs with a potentially dangerous interaction.
Drugs that can interact with St. John’s Wort include oral contraceptives, blood thinners, benzodiazepines, cancer chemotherapy medicines, digoxin, human immunodeficiency virus medicines, statins, immunosuppressants, selective serotonin reuptake inhibitors (SSRIs), and verapamil.
Clinical studies show that St. John’s Wort may be more effective than placebo in mild to moderate depression, but no better than placebo in major depression. There are several potential active ingredients, but it is still not clear what the clinical relevance of each ingredient is. These include naphthodianthrones, xanthones, flavonoids, phloroglucinols (e.g. hyperforin), and hypericin.
Doses of active ingredients can vary by as much as 17 fold from pill to pill, and herbal products in general are poorly regulated. A recent study found that most herbal products contained ingredients other than those listed on the label.
This latest study is a reminder that herbal treatments are drugs, but poorly understood and regulated drugs.