St. John’s Wort Drug Interactions and Health Benefits

St. John’s Wort


  1. St. John’s Wort has a long history of use for the treatment of insomnia and anxiety-related conditions.
  2. St. John’s Wort has been proven in clinical trials to be significantly more effective than a placebo in the treatment of mild depression; however, it is less effective than prescription antidepressants.
  3. Most people don’t know that many ‘natural’ supplements can negatively interact with prescription drugs. St. John’s Wort is a big example of this. Please consult your doctor before starting any St. John’s Wort treatments.

The Basics (For those who never took CHEM 101):

  1. St. John’s Wort is shown to be likely effective for therapy of mild depression.
  2. Side effects include: nausea, rash, fatigue, restlessness, and photosensitivity, though these may be rare.
  3. Consult a doctor before adding St. John’s Wort to your diet, since it has been shown to interact with the effectiveness of drugs such as combined oral contraceptives, cyclosporine, and indinavir.”

Note: Beware any supplement that makes bold safety and efficacy claims on the front of the bottle and hides a “This statement has not been evaluated by the FDA…” on the back. Many ‘all-natural’ products have been found in our testing to include contaminants and false claims.

Intermediate Information (For our favorite amateur researchers):

  1. According to the NIH, taking St. John’s Wort during pregnancy does not cause fetal defect nor does it affect cognitive development, but it may produce a lower birth rate.
  2. NIH states that, “Caution is warranted with the use of St John’s Wort during pregnancy until further high quality human research is conducted to determine its safety. St John’s Wort use during lactation appears to be of minimal risk, but may cause side effects.”
  3. St. John’s Wort can negatively affect the efficacy of antidepressants, HIV treatments, cancer drugs, and anticoagulants.” (National Library of Medicine)

Advanced Science (For those MD/Ph.D. geniuses):

  1. The use of St. John’s Wort is 23-55% more effective than placebo in the treatment of mild depression, but 6-18% lower compared to tricyclic antidepressants, according to the JAMA Network.
  2. Studies show that St. John’s Wort results in a CYP3A4 expression and because CYP3A4 is “involved in the oxidative metabolism” of more than half of all drugs, St. John’s Wort may show interaction with more drugs than previously thought. (National Academy of Sciences)
  3. “St John’s wort (Hypericum perforatum) lowers blood concentrations of cyclosporin, amitriptyline, digoxin, indinavir, warfarin, phenprocoumon and theophylline; furthermore it causes intermenstrual bleeding, delirium or mild serotonin syndrome, respectively, when used concomitantly with oral contraceptives (ethinylestradiol/desogestrel), loperamide or selective serotonin-reuptake inhibitors (sertaline, paroxetine, nefazodone).” (Clinical Pharmacology)