Last updated: Jun 15, 2008

Many well-designed studies agree that for mild to moderate depression, St. John's wort works, but does it stand up against prescription drugs like Prozac and Zoloft? Some studies say it does. A 2005 Cochrane study found that it is equally effective as some tricyclical antidepressants—and with fewer side effects. In the drug group, 23% reported agitation, upset stomach, dizziness, fatigue, anxiety, and sex problems. Among those taking St. John's wort, only 8% described side effects, most often an upset stomach. Similar results have been found in a study comparing the herb with the drug Zoloft. But recent research from the National Institute of Mental Health warns that St. John's wort isn't much help when it comes to major depression, and it is not a proven therapy for depression in general. See your doctor if you suspect you are suffering from the disease.

Dosage: In most studies showing benefits, people were given 900 milligrams of the herb a day.

Caveats: St. John's wort interacts with many medications, including birth control pills, possibly reducing their effectiveness, so talk to your physician or pharmacist before mixing meds with this or any other herb. Also, as with other life-threatening illnesses, don't self-medicate depression; talk to your doctor first.