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St. John's Wort

What Should I Know About It?

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Updated April 17, 2014

What is St. John’s Wort?

St. John’s wort (Hypericum perforatum) is one of the most commonly used herbs in the United States. It is a shrubby perennial plant with bright yellow flowers. St. John's wort was named because the flowers were said to bloom for the first time around June 24, the birthday of St. John the Baptist. The word "wort" means "plant" in Old English.

St. John’s wort has long been used as a folk remedy for emotional disorders. It was once thought to rid the body of evil spirits. St. John’s wort has also been used for wound healing and for a variety of other conditions.

There is debate about the active ingredient in St. John's wort. St. John's wort extracts are often standardized to hypericin, which led to the widespread belief that hypericin is the sole active compound. Another constituent called hyperforin has also been found to have antidepressant effects. A growing number of experts consider hyperforin to be the primary antidepressant compound. Recent research suggests other plant components called flavonoids and tannins may also have a medicinal effect. More research is needed.

Health Benefits of St. John’s Wort

St. John's wort is best known as a natural remedy for mild to moderate depression, but it is also being studied for other conditions.

1) Depression

Numerous studies in Europe, and more recently in the United States, have found that St. John’s wort is more effective than a placebo and as effective as tricyclic antidepressants for the short-term treatment (1 to 3 months) of mild to moderate depression. It appears to cause fewer side effects than many antidepressants, which is one of the main reasons it has become so popular.

At least two recent studies, however, didn’t find St. John’s wort to be more effective than a placebo for major depression. Some experts consider the studies to be flawed, due to inadequate dosages and an insufficient number of participants, which led to unusual results. For example, in one of the studies, the prescription antidepressant sertraline (Zoloft) had no effect on major depression. Another study found that St. John's wort was more effective than fluoxetine (Prozac) but not a placebo. The evidence for St. John's wort for major depression remains unclear. Until we have evidence that it works for severe depression, it should not be used as a substitute for proven treatments.

A study involving 150 people with minor depression or dysthymia found that St. John's wort was effective for minor depression (Hamilton Depression Scale score of up to 17), but that it wasn’t effective for people with dysthymia.

Learn about 8 depression remedies.

2) Anxiety

St. John's wort is also being studied as an anxiety remedy because, in some studies on depression, people taking St. John's wort also reported an improvement in anxiety. More research is needed.

Find out about other natural remedies for anxiety.

3) Obsessive Compulsive Disorder (OCD)

St. John’s wort has also been suggested as a possible treatment for OCD because the same medications (antidepressants) are often used for OCD, and because of promising results from a preliminary study. A later study on St. John's wort, however, didn’t find it more effective than a placebo for OCD.

4) Skin Conditions

Oil of St. John's wort, applied to the skin, was a folk remedy for skin injuries, nerve pain, burns and hemorrhoids. Although the oil is sold in some herbal stores, creams are also available. Some are standardized to hypericin or hyperforin, which are thought to have anti-inflammatory and antibacterial effects. St. John's wort also contains tannins, naturally occurring compounds thought to relieve skin irritations, such as those resulting from minor cuts.

5) Ear Pain

Some alternative practitioners recommend St. John's wort for ear pain due to an ear infection (otitis media). In one study of more than 100 children, a combination herbal ear drop that contained St. John's wort, garlic, calendula and mullein was found to be as effective as conventional ear drops.

6) Smoking Cessation

St. John's wort is being explored for smoking cessation. Although it is promising, well-designed studies are needed.

For other remedies for smoking cessation, read my Natural Remedies to Quit Smoking.

Other Conditions

St. John's wort has also been explored for conditions that can have psychological symptoms, such as insomnia, menopausal symptoms, premenstrual syndrome, seasonal affective disorder and attention deficit disorder. Further studies are needed before recommendations can be made.

Side Effects and Safety Concerns

In published studies, the most common side effects associated with short-term use of St. John’s wort supplements have included mild stomach upset; allergic skin reactions; tiredness; restlessness; anxiety; sexual/erectile dysfunction; dizziness; dry mouth and headache. If applied to the skin, St. John’s wort may cause a skin rash. St. John’s wort (both oral or topical) increases the sensitivity of skin and eyes to sunlight.

Rarely, St. John’s wort has been associated with serotonin syndrome, a potentially dangerous condition resulting from an excess of serotonin in the central nervous system. Symptoms include confusion, fever, hallucinations, nausea, loss of muscle coordination, sweating, and shakiness. Use with antidepressants, particularly SSRIs, has been associated with this. If you experience any of these symptoms, stop taking St. John’s wort and seek immediate medical attention.

Other Notes About St. John's Wort

  • St. John’s wort can be found in a variety of forms, including capsule, tablet, liquid extract, dry herb and tea. Oil and oil-based ointments and lotions can also available. Products are typically standardized to contain 0.3% hypericin or 2 to 5% hyperforin.

  • St. John’s wort may worsen symptoms in people with Alzheimer’s disease, bipolar disorder, schizophrenia or other mental conditions; it may also lead to psychosis or mania.

  • People with diagnosed or suspected depression should consult a doctor to ensure that their condition is properly assessed and treated.

  • Pregnant or breastfeeding women, and those trying to conceive, should avoid St. John's wort.

  • St. John’s wort should not be taken by organ transplant recipients, as it may cause organ rejection.

  • In one small study, St. John’s wort was associated with elevated thyroid stimulating hormone (TSH) levels.

  • Do not stop taking prescription drugs without consulting your doctor.

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