St. John's Wort

Medically Reviewed by Smitha Bhandari, MD on March 22, 2023
Written by R. Morgan Griffin
2 min read

For centuries, the flowering plant St. John's wort was used as a health remedy in Europe. Today, St. John's wort is best known as a treatment for depression.

Multiple studies have found St. John's wort helpful for depression. In fact, a few showed that St. John's wort was as effective as some prescription antidepressants. But the evidence is conflicting. Two recent major studies showed that St. John's wort worked no better than a placebo for moderate depression. However, neither did the medication that was used. St. John's wort might prove more effective for milder forms of depression. For now, however, the evidence is uncertain.

St. John's wort has also been studied in the treatment of other mood disorders, such as severe depression, anxiety disorders, obsessive compulsive disorder (OCD), and seasonal affective disorder (SAD.) It's also been used for insomnia, PMS, menopausal symptoms, and eczema. However, studies on St. John's wort for these uses have not shown solid evidence of benefit.

For depression, some clinical trials in adults have used 300 milligrams of St. John's wort (of 0.3% hypericin extract) taken three times a day for up to 6 months. After the initial treatment, some people choose to go onto a lower maintenance dose of 300 milligrams to 600 milligrams of St. John's wort per day.

There are no natural food sources of St. John's wort.

  • Side effects. At recommended doses, St. John's wort generally does not cause side effects. Uncommon side effects of St. John's wort include anxiety, dry mouth, sensitivity to sunlight, dizziness, stomach upset, headache, sexual problems, and fatigue.
  • Risks. Depression is a serious and potentially life-threatening disease. Never try to treat it on your own without the help of an expert. Given the lack of evidence about its safety, St. John's wort is not recommended for children or for women who are pregnant or breastfeeding.
  • Interactions. St. John's wort contains substances that can significantly alter the effectiveness of many drugs. You should talk with your doctor or pharmacist if you are on any medication and decide to use St. John's wort. You should not take St. John's wort if you're using antidepressants, birth control pills, blood thinners, medicines for HIV, cancer drugs, cyclosporine, or digoxin. St. John's wort may interfere with how these drugs work.