Saint-John's Wort

Nature’s Prozac

Depression is a common psychiatric disorder. It is estimated that about 15 percent of the population experiences symptoms of mild to moderate depression, while up to 5 percent experience severe depression at some time. Recently Saint-John’s-wort (Hypericum perforatum) has received a lot of attention as an herbal product that provides natural relief from depression.

Herbalists today recommend Saint-John’s-wort to treat wounds and to speed the healing of bruises and minor burns. Hypericum is highly valued for its sedative properties and treatment of mood disorders. Saint-John’s-wort is also highly prized as an antidepressant, without the side effects of conventional antidepressant drugs.

Saint-John’s-wort is a perennial herb that grows up to three feet tall in fields and along roadsides throughout North America and Europe. The plant is topped with a cluster of bright-yellow star-shaped flowers (with five slightly asymmetrical petals) that bloom from June to August.

The dried herb usually consists of the flowering tops, unopened buds, and uppermost leaves of the plant. It has a slightly sweet and aromatic odor and a mildly bitter, somewhat astringent taste. When ground into a powder it is usually greenish to yellowish-brown in color. When a high percentage of flowers and buds are used, the powder reflects more of a yellow color.

Clinical Information

The analysis of two dozen clinical trials involving more than 1,700 outpatients has revealed that Saint-John’s-wort, given for four to eight weeks’ duration, can be considered a safe and effective herb for the treatment of mild to moderate depression and anxiety. The advantage of Saint-John’s-wort is the very low risk of side effects. On the other hand, about 20 to 50 percent of patients using tricyclic antidepressants experience adverse side effects. The common side effects experienced include nausea, dizziness, fatigue, sedation, reduced sexual drive, headaches, dry mouth, and loss of appetite.

The people who took Saint-John’s-wort in the various clinical trials experienced significant improvement in depressive mood indicators such as feelings of sadness, hopelessness, helplessness, and fearfulness. Sleep difficulties and disruptive sleep patterns were also greatly improved after taking Saint-John’s-wort.

How Saint-John’s-wort Works

Saint-John’s-wort contains several active constituents, including various flavonoids and the naphthodianthrones, hypericin and pseudohypericin. Minor constituents in Saint-John’s-wort may also be partly responsible for the herb’s antidepressive activity. Clearly, the best procedure is to consume the total herbal product and not just a hypericin-rich extract. The flowering tops, including the flowers, buds, and uppermost leaves, contain the highest levels of flavonoids and hypericin. The antimicrobial activity of Hypericum is attributed to its essential oil, the phloroglucinols, and flavonoids.

Saint-John’s-wort is believed to act by altering the uptake and metabolism of brain chemicals, such as serotonin and norepinephrine. Serotonin is known to be a mood-altering substance, normally producing a calming effect. Another proposal suggests that Saint-John’s-wort reduces the level of the cytokine, interleukin-6, which may also alter mood.

Herbal Preparations

Analysis of clinical studies suggests that a daily dose of 900 milligrams of an extract of Saint-John’s-wort, containing 0.3 percent hypericin, is expected to provide therapeutic efficacy similar to that obtained with a synthetic antidepressant. High doses or prolonged use may sensitize the skin to sunlight exposure. Large amounts of hypericin may cause a phototoxic skin reaction.

Recommendations for use of the herb usually include drinking one to two cups per day of herbal tea made from one to two teaspoons of dried Saint-John’s-wort flowers steeped in a cup of boiling water for 10 minutes. Alternatively, a 300-milligram capsule standardized to contain 0.3 percent hypericin may be used up to three times a day. Normally, it takes about three to six weeks of regularly using Saint-John’s-wort before its therapeutic effects are observed.

Other Activities

A 1996 report revealed that Saint-John’s-wort may be useful in the treatment of chronic tension-type headaches. In another study researchers observed that extracts of Saint-John’s-wort given over a three-week period caused a significant increase in the production of nocturnal melatonin, a substance produced by the pineal gland that regulates circadian rhythms and helps prevent jet lag. Recently interest has focused on the antiviral activity of Saint-John’s- wort. A substantial activity against several retroviruses has been reported. Saint-John’s-wort is presently being researched for its usefulness in treatment of patients infected with HIV.


The herbal Physician’s Desk Reference states that no health hazards or side effects are known in conjunction with proper administration of designated therapeutic dosages of Saint-John’s-wort. Other opinions are that Saint-John’s-wort should not be taken along with Prozac or other anti-depressants. For example, excessive doses of Saint-John’s-wort may potentiate the effects of MAO inhibitors (an anti-depressant) therapy.


Saint-John’s-wort is an important plant medicinal for the treatment of mild to moderate depression. Its effectiveness and safety in long-term usage are, however, unknown at this time. It has also been suggested for the treatment of more severe forms of depression, but further clinical trials are needed to verify its usefulness.

In addition to its antidepressant effects, Saint-John’s-wort has been used historically for a wide variety of neurological conditions such as anxiety, insomnia, irritability, migraine headaches, and chronic neuralgia stemming from trauma and injuries. Furthermore, Saint-John’s-wort finds usefulness as a wound-healing agent, an anti-inflammatory and antiviral agent. While many have used it for the self-treatment of HIV/AIDS, objective data to verify its usefulness in this regard is lacking.

Remember: Herbal products and dietary supplements can have pharmacological effects, may produce adverse reactions in some people, and could interact with over-the-counter and prescription medications you may take. Discuss with your physician your decision to use any herbal product. Anything mentioned in this article is not intended to diagnose, prescribe, or treat any ailment.

Winston J. Craig, Ph.D., R.D., is professor of nutrition, Andrews University, Berrien Springs, Michigan.

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