St. John's Wort, a popular over-the-counter herbal remedy for depression, may cause temporary nerve damage in people who use it and are then exposed to sunlight. Increased sensitivity to sunlight is associated with use of the herb.

An investigator reports that following sunbathing, a female began feeling pain on the sunexposed parts of her arms and legs. She then sought medical attention. On physical examination, no skin burns were found. Even so, light touching, gusts of air, and cold caused "acute" pain in areas that had been exposed to sunlight. The pain lasted for a few seconds after the brushing, gusts of air, and cold exposure were terminated.

The woman's symptoms suggested nerve damage, or "subacute toxic neuropathy." She stopped using the herb and her symptoms began to improve. Over the following 2 months, her symptoms gradually disappeared. Compounds known as "photoactive hypericins" are among the active ingredients in St. John's Wort.

When exposed to light, these compounds produce substances that can damage cells. Myelin, the fatty insulation that wrap around nerves, is particularly vulnerable to this damage. If the myelin is damaged, symptoms appear similar to this patient's. Photosensitivity manifesting as toxic neuropathy has not previously been reported, but clinicians should be aware of such symptoms after St. John's Wort ingestion and exposure to the sun.

The Lancet October 3, 1998;352:1121-1122

Dr. Mercola's Comment:

Even the natural herbs have their side effects which is why I prefer food based supplements like tryptophan to St. John’s wort for the treatment of depression.