St. John’s Wort

St. John’s Wort
St. John’s Wort


There has been extensive research on St. John’s wort, especially on its use for depression and on its interactions with medications. It has been clearly shown that St. John’s wort can interact in dangerous, sometimes life-threatening ways with a variety of medicines.

Side Effects Of St. John’s Wort

St. John’s wort can weaken the effects of many medicines, including crucially important medicines such as:

  • Antidepressants
  • Birth control pills
  • Cyclosporine, which prevents the body from rejecting transplanted organs
  • Digoxin, a heart medication
  • Some HIV drugs including indinavir
  • Some cancer medications including irinotecan
  • Warfarin, an anticoagulant (blood thinner).
  • Taking St. John’s wort with certain antidepressants or other drugs that affect serotonin, a substance produced by nerve cells, may lead to increased serotonin-related side effects, which may be potentially serious.
  • It may cause increased sensitivity to sunlight. Other side effects can include anxiety, dry mouth, dizziness, gastrointestinal symptoms, fatigue, headache, or sexual dysfunction.


Depression can be a serious illness. If you or someone in your family may have depression, consult a health care provider.

Although it is important to tell all your health care providers about any complementary health approaches you use, this is especially crucial because this herb interacts with so many medicines. Interactions can weaken the effects of life-saving medicines or cause dangerous side effects.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.