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St. John's wort (also sometimes called Saint John's wort) is the common name for any member of a group of annual or long-living perennial herbs and shrubs with attractive five-petaled golden-yellow flowers. It is used by some people as a way to decrease the symptoms

of anxiety, depression, and various sleep disorders. St. John's wort is classified in the kingdom Plantae, division Magnoliophyta, class Magnoliopsida, and order Malpighiales. It is usually classified within the family Hypericaceae but is also sometimes found within the family Clusiaceae. Its genus is Hypericum.

When St. John's wort is used to refer to the herb used to treat illnesses such as depression, it is the species informally called Common St. John's wort. Sometimes also called Goat weed, hypericum, and Klamath weed, it is the most plentiful species of St. John's wort in the world. It is classified as genus/species Hypericum perforatum. As a perennial herb, St. John's wort has the ability to produce complicated underground creeping stems, called rhizomes. Its above-ground stems are straight and upright, branched within its upper half, and able to grow up to one meter (three feet) in height.

Besides H. perforatum, St. John's wort can also refer to the other species of St. John's wort including scrubby St. John's wort (Hypericum prolificum), great St. John's wort (Hypericum ascyron), and Jerusalem star, or rose of Sharon (Hypericum calycimum). In all, about 370 species of the genus Hypericum are found around the world.

Supposedly, the plant genus (Hypericum) was given its name—from the Greek words hyper (above) and eikon (picture)—in reference to John the Baptist, the first century A.D. Jewish religious leader. The exact reason for the naming is in question. Some of the possible reasons for its name include: the blooming of


Anticoagulants—Blood thinners.

Antiseptic—Medicine used to control infection.

Astringent—Substance that brings tissues together.

Extract—A compound in which something has been taken out so that it is now in a more purified state.

Placebo—An inactive substance (such as a sugar pill) used as a control in experiments.

Perennial—Reoccurring, as a plant that comes back for more than one growing season.

Rhizome—An underground creeping stem.

its yellow flowers in June around the time of John the Baptist's birth; the presence of the flower at a feast of John the Baptist; and the hanging of the flower over pictures in houses to supposedly protect against evil on St. John's day.


St. John's wort has been used for centuries to medically treat mental disorders such as depression and anxiety. The ancient Greek civilization is known to have used it for this purpose. Early Native Americans used it as anti-inflammatory (to control inflammation), antiseptic (to control infection), and astringent (to bring tissues together) medicines. The flowers of the plant have been used to treat depression, anxiety, and insomnia; sedate people; as a treatment for malaria; and a balm for burns, insect bites, and wounds. In recent history, parts of the plant have been used within herbal tea.

However, it is also considered a poisonous weed in over twenty countries. St. John's wort is considered a toxic weed that invades more productive plants and flowers. When eaten by domesticated animals, such as cows and horses, it can cause problems in the central nervous system, abortion in pregnant females, and even death.

The part of the St. John's wort used within such products are the flowers. They are reduced down to concentrated extracts; that is, specific non-essential substances that are removed to leave behind desired chemicals in a concentrated form. St. John's wort is sold in most countries as over-the-counter medicines in capsules and tablets, and as prepared herbal tea bags (in which boiling water is added to the dried herb and steeped). In other countries, such as Germany, it is used for mild depression more frequently than artificially made medically approved antidepressants.

The composition of St. John's wort and how it works is not well known nor understood. Some scientific evidence suggests it is useful for treating mild to moderate depression. Other recent reports state that it has no effect for treating major depression of moderate severity.


The St. John's wort plant is easily identified by its leaves and flowers. The toothless, stalkless, narrow, oblong leaves are yellowish-green in color, opposite to each other, and have tiny translucent spots scattered throughout the tissues and obvious black dots on the lower surface. When held up to light, the leaves appear to be perforated, which gives them their Latin species name perforatum. The leaves also contain glands that contain oil. The flowers are clustered with five petals. Each flower is about 12 to 20 millimeters (0.47 to 0.79 inch) long. The flowers are bright yellow in color with black dots. The five-petaled clusters grow up to 2.5 centimeters (about one inch) in diameter. The flowers bloom between April and July (late spring and early summer in the northern hemisphere). When the flowers or seed pods are crushed, a reddish purple liquid is produced.

As a genus, St. John's wort is native to the subtropical and temperate regions of Asia Minor, China, Europe, India, North America, and Russia and the other countries of the former Soviet Union. H. perforatum is actively cultivated in parts of southeastern Europe. It is indigenous to Europe but has been introduced into areas of the Americas.


The use of H. perforatum for the treatment of various medical problems has not been adequately documented. Previous clinical studies have largely concentrated on its effectiveness in clinically recognized depression,

Some studies show it is effective in mild to moderate depression while other studies show no benefit over placebos. Recent studies include a 2004 study called the Cochrane Review, which included 27 later studies. The results show that St. John's wort was significantly superior to placebos and similarly effective as general antidepressant medicines.

Between 1998 and 2005, numerous medical studies showed St. John's wort to be generally more effective than placebos and generally of equal effectiveness when compared to standard antidepressants, but with fewer negative side affects.

In 2002, the National Institutes of Health (NIH) funded a large and well designed research study called the Hypericum Depression Trial Study Group. Three organizations within the NIH coordinated the study: the National Center for Complementary and Alternative Medicine (NCCAM), the Office of Dietary Supplements (ODS), and the National Institute of Mental Health (NIMH). Three hundred, forty patients diagnosed with major depression of moderate severity were subjected to a double-blind placebo-controlled trial comparing St. John's wort to placebo. St John's wort was found to be no more effective than placebo.

St. John's wort has also been studied as a treatment for anxiety, obsessive-compulsive disorder, HIV (human immunodeficiency virus), atopic dermatitis (sometimes called eczema, a skin condition), and social phobia. In treatment of these illnesses, the results did not show anything conclusive about a positive affect that St. John's wort has on reducing symptoms. In all cases, there is insufficient evidence to make any recommendations.

In addition, the use of St. John's wort for such problems as premenstrual syndrome, depressed mood, seasonal depressive disorder, and somatoform (psychologically induced) disorders is controversial within the medical community.


Both the German Commission E, which is responsible for review of herbal and other alternative therapies, and the european scientific cooperative on phytotherapy have reviewed St. John's wort and found no interactions with other drugs.

St. John's wort may cause increased sensitivity to artificial light and light from the Sun. It may make some people sunburn more easily than normal. Some research shows that it may cause infertility in both men and women.

Other common side effects can be anxiety, dizziness, dry mouth, fatigue and weakness, gastrointestinal symptoms, headache, sleeping disorders, muscle cramping, nausea, and restlessness. More infrequently occurring side effects include: anorexia, constipation or diarrhea, increased periods of blood pressure and pulse, heartburn, increased sweating, loss of hair on scalp and eyebrows, numbness, tingling and nerve pain or damage, tremors, increased sweating and flushing (marked redness in face and other body areas), and tremors.

According to the National Institutes of Heath, when St. John's wort is ingested, it can alter the way that the body uses other drugs. In some circumstances, interactions can be dangerous. Some of these drugs include: drugs that treat HIV such as indinavir (Crixivan®); drugs that fight cancer such as irinotecan (Campto®); drugs that lower cholesterol such as lovastatin (Mevacor®), nifedipine (Procardia®), and midazolam (Versed®); drugs that reduce the rejection of transplanted organs such as cyclosporine (Sandimmune®); drugs that strengthen contractions of the heart muscle such as digoxin (Lanoxin®); drugs that act as anticoagulants (blood thinners) such as warfarin (Coumadin®); drugs that treat depressants such as amitriptyline (Elavil®); and drugs that control thyroid conditions such as levothyr-oxine (Synthroid®).


St. John's wort is generally well tolerated by the human body. Scientific studies show that the body readily accepts it at recommended doses for up to one to three months. Sometimes, if St John's wort is discontinued suddenly, there may be unfavorable withdrawal symptoms.

As with any ingested medicinal or herbal substance, there is always risk with taking too large an amount or having it react negatively with something else. Because St. John's wort is a dietary supplement the U.S. Food and Drug Administration (FDA) does not regulate it. Consequently, the strength and quality of it is not predictable within products sold by manufacturers. Products can differ from company to company, and more surprisingly, can change from batch to batch within a company. Information on labels can also be misleading because such data is not regulated by the FDA.

Parental concerns

If children have depression, St. John's wort is not a proven therapy for its treatment—in fact, it is not a proven therapy for the treatment of any depressed person. Parents of children suspected of being depressed should contact a medical professional for assistance. Effective treatments are available. Patients should be aware that if St. John's wort is used with standard anti-depressant therapies, it can cause side affects such as anxiety, confusion, headache, and nausea.

Medical professions also commonly warn pregnant or lactating women about taking St. John's wort. No adverse effects have been documented with the use of St. John's wort. However, because there are no published safety and health data, these women are advised to avoid the use of St. John's wort. Likewise, parents are advised not to give St. John's wort to their young children because of a lack of scientific evidence as to its safety.


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William Arthur Atkin