Q. I have friends in France who take St. John's wort for depression. Do you think this stuff works?

St. John's wort (Hypericum perforatum or Klamathweed) is one of the most commonly purchased herbal products in the United States. However, do not take this product unless you have consulted your family physician.The St. John's wort plant has been used as a medicine for many centuries. It was popular in ancient Greece. Today in Europe, it is used widely to treat mild-to-moderate depression.St. John's wort is a shrubby plant with clusters of yellow flowers. Both the flowers and leaves of the plant are used as medicine. St. John's wort can be obtained in capsules, tablets, tinctures, teas and oil-based skin lotions. Chopped or powdered forms of the dried herb are also available.The plant grows in Europe, Asia, Africa and the western United States. The plant is often in full bloom around June 24, the day traditionally celebrated as the birthday of St. John the Baptist.St. John's wort has antibacterial and antiviral properties. It fights inflammation and has been used to treat wounds. St. John's wort may help relieve some types of depression, but the evidence is not definitive.There is some scientific data indicating that St. John's wort may be helpful in treating minor depression. However, two large studies showed that the herb was no more effective than a placebo in treating major depression of moderate severity. One of these studies was sponsored by the National Center for Complementary and Alternative Medicine (NCCAM), which is part of the National Institutes of Health.St. John's wort contains several chemicals, including hypericin, hyperforin and flavonoids. Researchers aren't sure how St. John's wort works. Some have suggested that the herb acts like antidepressants by making more of the brain chemicals serotonin, dopamine and norepinephrine available. These chemicals known as neurotransmitters are mood elevators.It should be stressed that the herb can cause serious side effects. In general, herbal therapies are not recommended for the elderly, pregnant women, children, or those taking certain medicines.It is also important to note that the U.S. Food and Drug Administration has not approved St John's wort for use as an over-the-counter or prescription medicine for depression.Combining St. John's wort with certain antidepressants can lead to a potentially life-threatening increase of serotonin. St. John's wort can also limit the effectiveness of many prescription medicines such as antidepressants, some blood-pressure drugs, birth control pills, the heart medication Digoxin, some HIV drugs, blood thinners, antihistamines, cough medicines, sedatives, some cancer medications and statins that lower cholesterol.Other less threatening side effects of St. John's wort include stomach upset, hives or other skin rashes, fatigue, restlessness, headache, dry mouth, and feelings of dizziness or mental confusion. St. John's wort can also make the skin overly sensitive to sunlight.If you would like to read more columns, you can order a copy of "How to be a Healthy Geezer" at

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