St John’s Wort: A Success Story

Photo and Article by Ann Walker

St John’s wort is a traditional remedy used for low mood and depression and there is little doubt that it works well, as this use is well backed up by modern research. Indeed, over thirty well-designed clinical trials have proved that an extract of the herb can be as effective for mild-to-moderate depression as modern antidepressants (see reviews PMID: 28064110 and PMID: 27589952).

In fact, St John’s wort offers the best research-supported use of any herb on the planet for a single health condition! Nevertheless, herbalists in the UK were late in realising its potential for treating depression, although it had a long history of such use in the rest of Europe. UK herbalists from mid 1800s mainly used St John’s wort for treating anxiety, shingles and nerve pain, including sciatica, exploiting the herb’s anti-inflammatory and pain-killing properties. It also found particular use for a range of female conditions, including pre-menstrual syndrome and adverse menopausal symptoms. St John’s wort continues to be used by herbalists for nerve damage whether caused by physical, mental, or viral agents, but these days its use as an anti-depressant takes centre stage.

But a word of warning: St John’s wort is not suitable for everyone. Taken alongside certain modern drugs the herb substantially lowers their blood levels, rendering them less effective. While this only applies to a limited number of drugs, they include some whose levels in the blood are likely to be critical to their efficacy, including warfarin, cyclosporine, digoxin, some anti-cancer drugs and the contraceptive pill. The mechanism of action is though enhanced detoxication of these drugs by up-regulation of a specific enzyme pathway in the liver.

There are many pathways of detoxication in the liver, but only those drugs which are detoxified via the St John’s wort-activated pathway are affected. Hence, most modern drugs are not involved, but if you are taking any prescribed medication, it is important to read the accompanying leaflet to see it St John’s wort is contraindicated, or, failing that, to seek advice from a herbal practitioner such as a member of the College of Practitioners of Phytotherapy or of the National Institute of Medical Herbalists.

PMID = PubMed identifier

Ann Walker PhD, FCPP, MNIMH, RNutr
Course Director DHM
Herbal Practitioner