However, animals grazing on large amounts of St. John's wort may develop photosensitization, an allergic reaction that occurs with exposure to sunlight. Therefore, it is recommended that people taking St. John's wort try to minimize sun exposure, especially those with fair skin. Although there have been no reports of drug interactions, taking St. John's wort in combination with antidepressant drugs is not recommended. Recent research has suggested that St. John's wort may interact with certain drugs metabolized by the same liver enzyme system as the herb. Using St. John's Wort St. John's wort extracts and oil infusions are both made from the fresh flowering tops of the herb.
Extracts are available in the form of tinctures, tablets and capsules.
Unstandardized St. John's wort extracts have been used traditionally, but there has been little or no clinical research to assess their effectiveness. Two to three weeks of regular use may be needed before antidepressant effects are seen. The use of St. John's wort or other herbs is not a substitute for other medical treatment in cases of serious illness. Be sure to tell your doctor about any herbs you are taking. Educate yourself and use caution when practicing self-care.