page contents

Home / All About Herbs / About St. John’s Wort Monograph

st john's wort flowers

© 2018 Steven Foster

A St. John’s Wort monograph for the home

Latin Name: Hypericum perforatum

Common Names: St. John’s wort, hypericum, Klamath weed, goatweed

This St. John’s Wort monograph provides basic information about St. John’s wort—common names, usefulness and safety, and resources for more information.


St. John’s Wort Basics

  • St. John’s wort is a plant with yellow flowers that has been used in traditional European medicine as far back as the ancient Greeks. The name St. John’s wort apparently refers to John the Baptist, as the plant blooms around the time of the feast of St. John the Baptist in late June.
  • Historically, St. John’s wort has been used for a variety of conditions, including kidney and lung ailments, insomnia, and depression, and to aid wound healing.
  • Currently, St. John’s wort is most often used as a dietary supplement for depression. People also use it as a dietary supplement for other conditions, including menopausal symptoms, attention-deficit hyperactivity disorder (ADHD), and obsessive-compulsive disorder. It is used topically for wound healing.
  • The flowering tops of St. John’s wort are used to prepare teas, tablets, capsules, and liquid extracts. Topical preparations are also available.

St. John’s Wort in Health Research

  • 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.

St. John’s Wort Research Summary

  • The results of studies on the effectiveness of St. John’s wort for depression are mixed. For more information, see the NCCIH fact sheet St. John’s Wort and Depression.
  • St. John’s wort has also been studied for conditions other than depression. For some, such as ADHD, irritable bowel syndrome, and quitting smoking, current evidence indicates that St. John’s wort is not helpful. For others, such as menopausal symptoms, premenstrual syndrome, and obsessive-compulsive disorder, the evidence is inconclusive.

St. John’s Wort Safety

  • 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.
  • St. John’s wort may cause increased sensitivity to sunlight. Other side effects can include anxiety, dry mouth, dizziness, gastrointestinal symptoms, fatigue, headache, or sexual dysfunction.

St. John’s Wort References


PubMed Articles About Hypericum perforatum

Source: National Center for Biotechnology Information (NCBI)[Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; [1988] – [cited 2018 Apr 5]. Available from:

Eatemadnia, A., Ansari, S., Abedi, P., Najar, S., (2020) The effect of Hypericum perforatum on postmenopausal symptoms and depression: A randomized controlled trial.

Hypericum perforatum (St John's wort) is an herbal plant that has antidepressant activity and contains ingredients such as flavonols derivatives, bioflavonoids, proanthocyanidins, xanthones, phloroglucinol, and naphthodianthrones. This study was aimed to test the effect of Hypericum perforatum on hot flashes, menopausal symptoms, and depression in postmenopausal women.

Hajhashemi, M., Ghanbari, Z., Movahedi, M., Rafieian, M., Keivani, A., Haghollahi, F., (2018) The effect of Achillea millefolium and Hypericum perforatum ointments on episiotomy wound healing in primiparous women.

The purpose of this study was to assess the efficacy of Achillea millefolium and Hypericum perforatum ointments on episiotomy wound healing in primiparous women.

Yechiam, E., Ben-Eliezer, D., Ashby, NJS., Bar-Shaked, M., (2020) The acute effect of Hypericum perforatum on short-term memory in healthy adults.

Over-the-counter drugs containing Hypericum perforatum (H. perforatum) have been argued to improve memory and sustained attention. So far, these claims have not been supported in human studies. However, previous studies used rather high dosages, and little is known about the acute effect of small dosages.

Di Pierro, F., Risso, P., Settembre, R., (2019) Role in depression of a multi-fractionated versus a conventional Hypericum perforatum extract.

Hypericum perforatum is used as medicinal plant for mild to moderately severe depression. Several trials have found hypericum to be more effective than placebo or some antidepressant drugs, but the exact mechanism and most relevant compounds are still unclear. A possible hypothesis is that the antidepressant activity might be due to its multiplicity of bioactive compounds. Aim is to test if greater chemical complexity could result in a greater hypericum antidepressant action.

Concerto, C., Boo, H., Hu, C., Sandilya, P., Krish, A., Chusid, E., Coira, D., Aguglia, E., Battaglia, F., (2018) Hypericum perforatum extract modulates cortical plasticity in humans.

Hypericum perforatum (HYP) extract is one of the most commonly used complementary alternative medicines (CAMs) for the treatment of mild-to-moderate depression. Non-invasive brain stimulation protocols can be used to investigate the effect of psychoactive substances on the human brain. In this study, we explored the effect of a single dose of HYP extract (WS 5570) intake on corticospinal excitability and plasticity in humans.