St. John's Wort

March 21, 2017

St. John's Wort

Botanical name(s):

Hypericum Perforatum. Family: Hypericaceae

Other name(s):

amber, goatweed, hardhay, hyperici herba, klamath weed, tipton weed

General description

St. John's wort is an herb. It has a five-petaled yellow flower. It grows in much of the world. It’s named after St. John the Baptist. This is because it blooms around his celebration day (June 24). The medicinal part of the plant is made up of the dried above-ground parts. These include the stem, petals, and flowers.

Two constituents that play a major role are hypericin and hyperforin. These and other related compounds are the main active parts. They may affect serotonin, dopamine, and norepinephrine. These are neurotransmitters in your body. 

Medically valid uses

St. John's wort is used to treat mild to moderate depression. Studies show that it works just as well as prescription antidepressant medicines for these conditions. But St. John's wort doesn’t work to treat major or severe depression. 

You can apply oily hypericum forms directly to your skin. It can help treat injuries, muscle pain, and first-degree burns.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through studies.

St. John's wort has been said to work as the following:

  • Muscle relaxant. It’s used to ease menstrual cramps.

  • Mild tranquilizer

  • Nerve tonic. It may have a positive effect on the nervous system.

  • Anti-inflammatory. It may reduce swelling.

  • Astringent. This action contracts tissues or canals of the body.

  • Vulnerary. This may heal wounds and swelling.

  • Antineoplastic. This means it may fight cancer.

  • Antiviral. It may help fight viral infections. These can include herpes and human immunodeficiency virus (HIV).

St. John's wort has also been claimed to be good for nerve pain (neuralgia), anxiety, and tension. It may also aid in weakness, stress, irritability, and sleeping issues (insomnia). It’s also claimed to ease the pain due to some conditions. These include sciatica, rheumatoid arthritis, and menstruation. It may also ease the itching and burning of hemorrhoids and vaginitis.

When you apply it topically, St. John's wort is said to speed healing in certain conditions. These include bruises, wounds, varicose veins, mild burns, and sunburns.

Dosing format

St. John's wort comes in many forms. These include oil, dried herb, tea, and salve.

It may take four to six weeks for St. John’s wort to work. If it doesn’t work after this amount of time, you should consider other treatments.

Side effects, toxicity, and interactions

St. John's wort can interfere with other medicines. These include the following:

  • Medicines that prevent organ rejection after an organ transplant. You shouldn’t use St. John’s wort if you’ve had or plan to have an organ transplant.

  • Birth control pills

  • Digoxin

  • Seizure medicines

  • Blood thinners

  • HIV medicines

  • Antidepressants

  • Cancer chemotherapy medicines

St. John’s wort can keep your body from absorbing iron and other minerals.

In large amounts, St. John's wort can make you more sensitive to the sun. This is especially true for people with fair skin. Stay out of the sun as much as you can. When you must be in the sun, wear sunscreen.

Don’t take large amounts of St. John's wort. Follow the directions on the package.

You shouldn’t take St. John's wort if you have major depression. You also shouldn’t take it if you’re taking a medicine to treat depression.  

Women who are pregnant or breastfeeding should talk to their healthcare providers before taking any supplements.


March 21, 2017

Reviewed By:  

Poulson, Brittany, RD, CDE,Wilkins, Joanna, R.D., C.D.