St. John's wort is an herbal supplement used by some people mainly to relieve mild to moderate depression. Some individuals also use it for conditions such as anxiety, sleep problems, premenstrual syndrome (PMS) and menopausal symptoms. The active ingredients in St. John's wort come from a plant with yellow flowers that has been used for centuries to treat a variety of medical conditions.

The effectiveness of St. John's wort in treating various disorders remains unproven, although some studies appear to show a benefit in relieving symptoms of minor depression.

St. John's wort is available in tea, capsule and extract form. Because it is a dietary supplement, the U.S. Food and Drug Administration does not regulate this over-the-counter product. Formulations sold under the name St. John's wort may contain very different active ingredients in varying amounts.

St. John's wort may cause the body to break down other medications more quickly or slowly. For this reason, the supplement has the potential to create significant and negative interactions when used with other medications, particularly antidepressants. Individuals taking any medication should talk with their physician before taking any herbal supplements. People taking birth control pills or certain heart, cancer or other drugs also may be advised to avoid St. John's wort.

People who experience depression or any other mental illnesses are at serious risk of major health consequences, including suicide. Therefore, patients should contact a physician for an appropriate diagnosis and intervention rather than trying to treat themselves with St. John's wort.

St. John's wort is an herbal supplement used to treat several medical conditions. It is most often used to treat mild to moderate depression, although many claim that it is also effective in treating several other mental and physical health conditions.

St. John's wort (Hypericum perforatum) is a plant with yellow flowers that contains certain chemical compounds. For centuries, the flowering tops of St. John's wort have been used to make teas, pills and powders to treat various mental disorders and nerve pain. Herbalists from ancient times wrote about the power of this herb when used as a sedative, malaria treatment and balm for wounds, burns and insect bites.

It is believed that the compounds hypericin and hyperforin are the active ingredients that produce the herb's effects, but scientists remain unsure of the exact composition of St. John's wort and how it might work. Some studies suggest that St. John's wort might prevent nerve cells in the brain from reabsorbing the neurotransmitter serotonin, or might reduce levels of a protein involved in the function of the body's immune system.

Today, St. John's wort is used primarily by patients who do not find relief from antidepressants, or who experience unpleasant side effects from using antidepressants, such as a dry mouth, nausea, headache, or effects on sexual function or sleep.

Some people may believe that an "all-natural" supplement is healthier or more effective than prescription medication. This is an assertion that many physicians and the U.S. Food and Drug Administration (FDA) say is incorrect and potentially dangerous.

St. John's wort is available in the following forms:

• Capsules.
• Teas. Dried herb is added to boiling water and steeped.
• Extracts. Specific chemicals are removed from the herb, and the active ingredients are gathered in a concentrated form.

In recent years, the potential effectiveness of St. John's wort in treating depression has been a source of controversy. Some researchers believe that it is at least as effective as antidepressant medications in relieving depression. Others maintain that the alleged benefits of St. John's wort have not been scientifically proven and are largely unfounded.

Several smaller European studies have suggested that St. John's wort is useful in treating mild to moderate depression. However, a larger trial of 340 subjects funded by the National Institute of Mental Health (NIMH), the Office of Dietary Supplements (ODS) and the National Center for Complementary and Alternative Medicine (NCCAM) resulted in a different response. It found that an extract of the herb St. John's wort was no more effective in relieving moderately severe depression than a placebo (an inactive substance used as a control in an experiment).

It is important to note that the FDA does not regulate herbal supplements. As a result, different products sold as St. John's wort may have varying levels of the active ingredient. The difference from one product to another in the amount of active ingredient makes it difficult to determine how effective a product will be. In addition, ingredients in herbal supplements may vary quite a bit from one batch to another, meaning that side effects can be widely variable as well.

Depression is a major mental health illness that can impair a person's quality of life and even lead to suicidal thoughts and acts if left untreated. Patients who experience depression or any other disorder are encouraged to contact a physician for treatment options rather than trying to treat themselves with St. John's wort.

Other names for St. John's wort include goat weed, hypericum, Klamath weed, balm of warrior's wound, balsana, bassant, bossant, corancillo dendlu, devil's scourge, flor de Sao Joa, fuga daemonum, heofarigo on, herba de millepertius, herba hyperici, herrgottsblut, hexenkraut, hierba de San Juan, hipericao, HP, isorhamnetin, liebeskraut, LI 160, lord God's wonder plant, millepertius pelicao, perforate, pinillo de oro, PM235, pseudohypericin, rosin rose, SJW extract LI 160, STW 3-VI, tenturotou, touch and heal, witcher's herb and WS 5572.

St. John's wort may be used for a variety of conditions, but is chiefly used by individuals to treat depression. Some studies have indicated that the supplement may be effective in treating some cases of mild depression. Some individuals believe that St. John's wort is at least as effective as tricyclic antidepressants in treating mild depression. Studies with other antidepressants are more limited. Studies of St. John's wort in treating major depression have not shown clear evidence of effectiveness.

Some individuals also believe that St. John's wort may be effective in treating other problems, such as:

• Anxiety
• Sleep problems
• Seasonal affective disorder (SAD)
• Menopausal symptoms
• Premenstrual syndrome (PMS)

To date, there is no conclusive evidence that these conditions respond to St. John's wort, although some initial studies have yielded positive results for some patients.

The Natural Standard Research Collaboration, an international organization that reviews complementary and alternative therapies, says there is strong scientific evidence for the use of St. John's wort in treating mild to moderate depression. It says there is unclear scientific evidence on using it to treat severe depression, anxiety disorder, atrophic dermatitis, menopausal symptoms, nerve pain, obsessive-compulsive disorder, premenstrual syndrome, seasonal affective disorder and somatoform disorders (physical symptoms that seem to have psychological causes) -- and says there is scientific evidence against using it to treat HIV or social phobia.

St. John's wort is an herbal supplement. Therefore, it is not regulated by the U.S. Food and Drug Administration, and different batches may contain different active ingredients in varying amounts. Because there can be significant interactions with other drugs and other herbal supplements, it is recommended that patients experiencing symptoms of depression or another illness consult their physician before using St. John's wort.

In most cases, St. John's wort does not produce adverse effects when used between one and three months. However, side effects can occur and often are not listed on product labels. These include minor nausea, insomnia, unusual skin sensitivity to the sun (photosensitivity) and allergic reactions, such as rash or itchiness.

Other side effects include gastrointestinal upset, fatigue, sedation, restlessness and anxiety. Individuals have also reported sexual dysfunction (including impotence), dizziness, headache and dry mouth. Some foods such as cheeses and red wines may cause an interaction with St. John's wort that increases blood pressure. Use of St. John's wort also has the potential to interfere with the results of certain laboratory tests.

The supplement may trigger mania or hypomania in patients with bipolar disorder, in which patients experience extreme swings in mood. Patients often do not recognize the "highs" of bipolar disorder as an issue, and bipolar disorder is often misdiagnosed as depression. A person who takes St. John's wort for a depressive episode may inadvertently cause a manic or hypomanic episode, which can impact many different areas of life negatively.

Because St. John's wort is an herbal supplement, it is not regulated by the U.S. Food and Drug Administration. Therefore, different batches may contain different active ingredients in varying amounts. It is recommended that patients experiencing symptoms of depression or another mental illness notify their physician before using St. John's wort.

Patients should consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

St. John's wort has been shown to affect liver enzymes and liver metabolism. As a result, it causes the body to break down many medications more quickly. This means that the supplement has the potential to create significant and negative interactions when used with other medications resulting in a decrease in concentration or effect of the medicine.

Patients who take St. John's wort with antidepressants are particularly at risk for significant interactions. Symptoms associated with simultaneous use of antidepressants and St. John's wort include nausea, anxiety, headaches and confusion. No patient should use antidepressants and St. John's wort at the same time, or switch from using an antidepressant to using St. John's wort, without first consulting a physician.

Though there has been little study of the effect of St. John's wort on bipolar disorder, it is possible that, as with antidepressants, St. John's wort may cause patients with this condition to become manic, especially if they are not taking a mood stabilizer.

The U.S. Food and Drug Administration (FDA) issued a warning in 2000 that St. John's wort may affect a metabolic pathway used by many medications to treat conditions such as AIDS, heart disease, depression, seizures, certain cancers and rejection of transplants.

Examples of drugs affected by St. John's wort include:

• Certain immunosuppressants (drugs used to prevent the body from rejecting transplanted organs)
• Certain heart and blood pressure drugs
• Certain drugs used to control HIV infection
• Certain drugs used to treat cancer
• Some anticoagulants
• Birth control pills

To date, there has not been enough research to recommend St. John's wort for use in pregnant or nursing women.

There are reports of unintended pregnancies in women taking birth control pills and St. John's wort at the same time.