Origin: The yellow flower, leaves and stem of the St. John’s wort plant, is native to Europe and grows wild in the U.S.
Dosage: Extract in the form of powder (dried), liquid (10 to 60 drops one to four times per day) or tablet, capsules and tea; extract, typically 900 mg daily.
Claims: Acts as an antidepressant drug and reduces inflammation and pain.
What we know: St. John’s wort’s mood-elevating properties were believed to be from active ingredients hypericin and hyperforin, chemicals that raise levels of serotonin, a chemical found in the brain. Serotonin levels may be low in people who are depressed and possibly in those who have fibromyalgia. New research, however, suggests the whole preparation (not just the two active ingredients) is more effective.
Studies: No scientific evidence shows that St. John’s wort is effective for reducing inflammation. A Cochrane Review of studies on St. John’s wort for depression showed that current evidence is inconsistent. A study also found that the herb is not effective for social anxiety disorder.
Although St. John’s wort taken alone is considered safe, it is potentially dangerous if taken with prescription anti-depressants. St. John’s wort can cause insomnia, restlessness, anxiety, irritability, stomach upset, fatigue, dry mouth, dizziness or increased sensitivity to sunlight. Consult your physician before taking St. John’s wort if you are already taking any kind of prescription medications. Do not take it if you have Alzheimer’s disease, HIV, depression, schizophrenia, infertility or bipolar disorder. It may also reduce effectiveness of oral contraceptives.