ST JOHN'S WORT (Hypericum perforatum)

Possible applications: Acquired Immunodeficiency Syndrome Anxiety Depression

A shrubby plant native to Europe and the USA (see MORE INFO below) which researchers have shown in preliminary studies to contain hypericin and pseudohypericin which inhibit a variety of retroviruses including the retrovirus associated with AIDS. More research is recommended, but clinical research has shown it effective for relief of depression. Hypericin has been shown effective in the treatment of the Epstein-Barr virus. It has also been shown more effective in the treatment of depression than amitriptyline and imiprimine. St John's Wort does not, unlike these drugs, produce the drowsiness, dry mouth, constipation and impaired urination associated with the amitriptyline and imiprimine. Since it has been shown to cause severe photosensitivity in animals grazing extensively on the plant, there is some evidence that St John's Wort, taken at high doses could potentially produce photosensitivity in humans. St John's Wort has been shown to improve mood as well as sleep quality.

TOXICITY RATING: Low to moderate.

ANIMALS AFFECTED: Cattle, sheep, goats, horses, and swine.

DANGEROUS PARTS OF PLANT: All parts.

CLASS OF SIGNS: Sunburn, skin slough, eye irritation.

PLANT DESCRIPTION: This perennial herb grows 1 to 11/2 feet 1/2 to 1 inch long and flat-topped clusters of golden yellow flowers 3/4 to 1 inch broad which bloom from midsummer to late fall. The five petals often have distinctive black dots around their edges and the leaves may have similar dots. St. Johnswort commonly grows in droughty, poor, or over-grazed meadows, pastures, fields, and waste areas, usually on dry, gravelly, or sandy soils in full sunshine. Other species of Hypericum occur in Indiana, some as garden plants. Although the evidence of their toxicity is not as clear, it may be prudent to avoid them, too.

SIGNS: The toxin in St. Johnswort is called hypericin. When animals ingest the plant, the hypericin is absorbed from the intestinal tract and goes into the circulation. Hypericin is photodynamic, able to convert sunlight into energy (primarily heat), causing cellular damage and sunburn (which can be severe). Cattle and sheep are the most sensitive to this toxin, but swine and horses may also be affected.

ŠJamie Longstreet 1996-2004