St. John's Wort

How does St. John's Wort work?

For a long time, investigators thought a chemical in St. John's wort called hypericin was responsible for its effects against depression. More recent information suggests another chemical, hyperforin, may play a larger role in depression. Hypericin and hyperforin act on chemical messengers in the nervous system that regulate mood.

Are there safety concerns?

St. John's wort is safe for most people when taken by mouth short-term. It can cause some side effects such as insomnia, vivid dreams, restlessness, anxiety, irritability, stomach upset, fatigue, dry mouth, dizziness, headache, skin rash, diarrhea, and tingling.

St. John's wort can cause skin to become extra sensitive to the sun. Wear sunblock outside, especially if you are light-skinned.

Do not use St. John's wort if:
  • You are pregnant or breast-feeding.
  • You are trying to get pregnant or father a child.
  • You have attention deficit-hyperactivity disorder (ADHD).
  • You have bipolar disorder.
  • You have schizophrenia.
  • You have Alzheimer's disease.
  • You have major depression.
  • You are scheduled for surgery in the next two weeks.

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Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.