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St. John’s Wort

Compilation by Armando Gonzalez Stuart, PhD

Scientific Name:

Hypericum perforatum

Other Common Name:

Klamath Weed, Hypericum, Hierba de San Juan, Corazoncillo, Hipérico.

Parts of the plant used:

Mainly the leaves and flowers.

How is it used?

SJW may be used as a crude herb to prepare a tea and is also available in capsules, tablets, tinctures and extracts.

What is it used for?

Limited data suggests that SJW may be efficient as an antidepressant in mild to moderate depression. Its effectiveness in severe depression, however, has not been documented. Therefore, persons with severe depression should promptly seek treatment by a professional therapist and should avoid self-diagnosis, as well as self-medication. This herb has been used in Europe to treat skin infections and small wounds externally, as well as internally to treat nocturnal bed-wetting in children. SJW also exhibits antibacterial and antiviral activity. It has been used externally for many years in Europe to treat minor cuts and bruises.

Safety / Precautions

  • Preparations containing this herb may interfere with the actions of certain medications such as protease inhibitors, used to combat the virus (HIV) that causes AIDS. If a conventional antiviral drug, such as Indinavir, for example, is taken along with SJW, the efficacy of the medication may be diminished.
  • Do not mix SJW with other antidepressant drugs, since a potentially dangerous reaction may occur. The same is applied to anxiolytics (drugs to diminish anxiety), as well as sedatives or sleep inducers.
  • The efficacy of oral contraceptives may be diminished if taken with SJW, so be sure to check with your gynecologist before taking any herbal product or supplement that contains this plant. The risk for an unplanned pregnancy exists if a woman who takes oral contraceptives during treatment with SJW.
  • Avoid taking SJW during pregnancy and lactation, since its effects on the development of the human fetus have not been adequately studied. The herb could cause uterine contractions.
  • People taking more than 1800 mg. of SJW a day, should exercise caution if exposed to direct sunlight or ultra violet light for prolonged periods of time, since a skin reaction may occur, causing blistering and dermatitis, especially in light-skinned individuals.

Before you decide to take any medicinal herb or herbal supplement, be sure to consult with your health care professional first. Avoid self-medication: Always be on the safe side!