Herbs & Supplements

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Uses

Used from time to time since ancient days to treat a number of various conditions, St. John's wort has become popular again as an antidepressant. It contains several chemicals, including hypericin, hyperforin, and pseudohypericin, which are thought to be the major sources of its antidepressant activity. In several studies of laboratory animals and humans, one or more of the chemicals in St. John's wort appeared to delay or decrease re-absorption of the neurotransmitters dopamine, norepinephrine, and serotonin by nerve cells. Neurotransmitters are chemicals that carry messages from nerve cells to other cells. Ordinarily, once the message has been delivered, neurotransmitters are re-absorbed and inactivated by the cells that released them. Chemicals in St. John's wort may keep more of these antidepressant neurotransmitters available for the body to use. Multiple studies have shown that St. John's wort may be effective in relieving mild to moderate depression, although maximum antidepressant effects may take several weeks to develop.

However, other studies have challenged the antidepressant effects of St. John's wort. At least two recent large, well-controlled clinical studies found no difference in relief of major depression among individuals who received St. John's wort and those taking placebo (inactive sugar pills). In one of the studies, a prescription antidepressant medication also showed no significant effect on major depression. Whether the studies lasted long enough and whether the doses of antidepressants and St. John's wort were high enough to produce significant effects may be questionable. In 2003, the U.S. National Institute of Mental Health began a 4-year clinical study to compare the effectiveness of St. Johns wort with both a prescription antidepressant and placebo for treating mild depression. Results of that study have not yet been published

In addition to its potential for depression, St. John's wort has also been studied for the treatment of other emotional disorders such as anxiety, obsessive-compulsive disorder (OCD), menopausal mood swings, and premenstrual syndrome. It is believed that chemicals in St. John's wort may act like other chemicals that are associated with relieving emotional conditions. These effects are poorly understood; however, and results of the studies are mixed, with a few finding possible effectiveness and others finding no difference between placebo and St. John's wort. Currently, studies sponsored by the National Center for Complementary and Alternative Medicine, a part of the U.S. National Institutes of Health, are underway to test the effectiveness of St. John's wort for OCD and social phobia as compared to placebo. More studies are planned for determining the usefulness of St. John's wort in treating these mental conditions.

In laboratory studies, St. John's wort has shown some effectiveness for lessening the symptoms of nicotine or alcohol withdrawal and for reducing the craving for alcohol in addicted animals. In one small human study, about 35% of smokers who took St. John's wort while they were trying to quit maintained smoking cessation for at least 12 weeks.

Possible antiviral effects of St. John's wort are being investigated for the treatment of HIV/AIDS, hepatitis C, and other viral illnesses. Hypericin, pseudohypericin, and other chemicals in St. John's wort are thought to stick to the surfaces of viruses and keep them from binding to host cells. Another theory is that St. John's wort may contain chemicals that interfere with the production or release of viral particles. This antiviral activity is enhanced greatly by exposure to light. However, the doses needed for active antiviral effect from St. John's wort may be so high that unbearable side effects may limit its usefulness as an oral antiviral. More research is needed to prove or disprove the effectiveness and to determine effective dose levels of St. John's wort for viral illnesses.

Although taking it orally is more common, St. John's wort may also be applied to the skin. In some parts of Europe, it is used widely as a treatment for topical infections. It has mild antibiotic effects, which are thought to be attributed mainly to its hypericin content, although a cream containing 1.5% hyperforin has also been found useful in studies for treating dermatitis. Hypericin also seems to have an additional anti-inflammatory effect caused by interrupting the body's production of natural chemicals that promote inflammation. Additionally, St. John's wort contains between 3% and 15% of a chemical group known as tannins, which act as astringents. An astringent shrinks and tightens the top layers of skin or mucous membranes, thereby reducing secretions, relieving irritation, and improving tissue firmness. St. John's wort may also promote the healing of broken skin by speeding up the skin's production of protein fibers. All these properties may make topical St. John's wort moderately useful for minor skin irritations such as cuts, razor burn, and scrapes. Studies comparing long-term use of topical St. John's wort against prescription treatments that are applied for skin conditions are needed to determine its true effectivenes, however.

In very early studies, the ability of St. John's wort to sensitize the skin to ultraviolet (UV) light has been tested as a treatment for skin cancers and other skin conditions. In small studies of humans, individuals took St. John's wort orally and thenthe affected areas of skin were exposed to UV light two hours later. In general, the results have been mixed with some individuals experiencing complete elimination of the conditions, but most achieving only partial response or no improvement. All study participants found the treatment painful, however, and much more study is needed to prove or disprove its effectiveness.