St John's wort is saviour for mild depression


DOES IT WORK: DÓNAL O'MATHÚNAon St John’s wort and depression

ST JOHN’S wort is a controversial herbal remedy. A number of studies have shown that it has some effectiveness as a treatment for mild to moderate depression and, as a result, oral formulations are available only on prescription in Ireland and many other countries.

Although this regulation remains controversial, it is based on the belief that people who are depressed should consult their doctor before using medication and concerns about the potential interactions of St John’s wort with other medications.

Those who disagree believe that people should be able to decide for themselves whether to use herbal remedies and that the regulations have more to do with controlling the market than protecting patients. The focus here will not be on the regulations, but to give an update on recent research into the herb.

The botanical name for St John’s wort is Hypericum perforatum. The name comes from John the Baptist because the flower blooms towards the end of June, close to his Feast Day.

Also, when the buds and flowers are squeezed, a red pigment exudes that is said to represent the blood of John the Baptist. Wort is an old English word for plant.

Recent interest in the herbal remedy stems from it being officially licensed in Germany as an antidepressant in 1988. German physicians write more prescriptions for St John’s wort than any other pharmaceutical antidepressant.

Evidence from studies

Much research has been conducted to find its most active ingredient. The most recent studies indicate that at least seven types of compound play a role in its antidepressant activity.

Although some purified compounds have been tested, the total extract seems to be the most effective.

In 2005, a review of all the research concluded that St John’s wort was more effective than placebos in treating mild to moderate depression. Studies that compared St John’s wort to pharmaceutical antidepressants found them similarly effective, but with St John’s wort having fewer side effects.

But it remained unclear whether St John’s wort was effective in patients with more serious depression, called major depression. The World Health Organisation estimates that by 2020 major depression will be the second leading cause of disability in the world.

The 2005 review concluded that the available evidence on major depression was contradictory and inconclusive. Another review was published at the end of 2008 and found 18 good-quality studies of St John’s wort for major depression.

Overall, the results indicated that St John’s wort is more effective than placebo and similarly effective to pharmaceutical antidepressants. But the results of these studies varied considerably, something which is difficult to interpret. It may reflect differences in the quality of the products used.

This is a problem with St John’s wort and many herbal remedies. Also, the reviewers found that studies conducted in Germany had more positive results than those conducted elsewhere.

This might reflect the greater familiarity German physicians have with St John’s wort and herbal medicine in general, or it could reflect a bias in favour of the remedy. Nevertheless, the review showed that overall St John’s wort can be expected to have a “modest” effect on symptoms of major depression.

Problematic aspects

St John’s wort has few adverse effects when used to treat mild to moderate depression, and the same has been found with major depression. However, numerous drug interactions have been reported with St John’s wort.

Several compounds in the herbal remedy impact the way in which the body eliminates pharmaceuticals.

This leads to higher blood levels of some drugs and lower levels of others, some of which have led to serious complications.

The list of drugs affected continues to grow, some estimating that almost half of all prescription drugs might be affected. So it is vital that people taking St John’s wort discuss this with their doctor and pharmacist.


St John’s wort should serve as a reminder that herbal remedies can be effective treatments for particular conditions. High-quality clinical trials can be conducted on herbs and can reveal if they are effective.

This is reflected in the growing worldwide sales of St John’s wort, now estimated to be almost half a billion euro each year.

St John’s wort should also remind us that herbal remedies that work are drugs. As such, they need to be used carefully and appropriately.

Dónal OMathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University