Neurotoxicity from Whole St. John’s Wort

January 1999; Volume 2: 12

Source: Bove GM. Acute neuropathy after exposure to sun in a patient treated with St. John’s wort. Lancet 1998; 352:1121-1122.

A 35-year-old woman took ground whole St. John’s wort (500 mg/d) for mild depression, after reading a magazine article. After 4 weeks, she developed stinging pain on her face and dorsum of both hands (areas exposed to the sun). Spontaneous pain was mild but worsened during and after being in the sun. Pain was provoked by minimal mechanical stimuli such as light touch or air movement. Cooling increased and warming decreased the pain. She sought help when the same symptoms developed on her arms and legs a few hours after sunbathing, and were limited to the exposed skin.

Examination two weeks after the pain started revealed allodynia but no skin burns, or other motor or sensory changes. Brushing lightly, blowing air, and cold temperature exacerbated the pain. Three weeks after discontinuation of the botanical, the symptoms began to improve, and gradually disappeared over the next two months.

The patient’s symptoms were consistent with demyelination of cutaneous axons. Photoactive hypericins produce cytotoxic singlet oxygen and free radicals when exposed to light. Lipid peroxidation occurs as a result, and myelin may suffer.


St. John’s wort seems ubiquitous. In 1997 U.S. sales topped $47 million. Robert’s Potato Chips now come laced with the stuff. So do new Celestial Seasonings teas (drink 36 cups, get 900 mg of something). A division of Boehringer Ingelheim Pharmaceuticals is promoting a brand. And Germany had, as of 1995, 18 single-herb hypericum products. Is it in the water, as Walker Percy feared? And how much can harm you?

This patient apparently ingested St. John’s wort’s ground yellow, star-shaped flowers and buds. Grazing animals, especially cows and sheep, have had phototoxic reactions to the same whole flower preparation. The species used to make the medication is just one of 378 known. The author, from Boston’s Beth Israel Deaconess, references a report of photosensitivity and pigment changes after St. John’s wort ingestion in humans.

St. John’s wort photosensitization is dose-related, and has occurred with plasma concentrations of 50 mcg of hypericin per ml, according to Schulz’ Rational Phytotherapy—six orders of magnitude above what patients who take an extract of 300 mg of 0.6% hypericin tid should have.

Typically, of course, patients do take extracts. In Alternative Medicine Alert (1998;1:6) Hornig reports: "Side effects are infrequent and typically mild. The overall incidence of side effects in the 23 studies included in the meta-analysis (of 23 studies) by Linde et al was 19.8% for hypericum compared with 52.8% for standard antidepressant therapy (BMJ 1996; 313:253-258.) ... The most common side effects of the herbal extract [administered at the suggested dosage] include dry mouth, dizziness, gastrointestinal complaints (most commonly constipation) and confusion."


Ask patients not to make their own teas, powders, brownies, or anything else from whole St. John’s wort. There’s no telling what they’re getting, and free radical damage and neurotoxicity are real possibilities.