What works

The definitive guide to treating common ailments

No 32: St John's Wort

St John's Wort has become highly popular for treating depression and is widely available. There is now compelling evidence that the herbal remedy works. Numerous trials show it is more effective than placebos. Several studies also suggest it is just as effective as some antidepressants, with fewer short-term side-effects.

Conventional treatment for depression:
About one in four people will suffer depression at some time in their lives. If you visit a GP you may be offered antidepressants - either tricyclics or selective serotonin reuptake inhibitors (SSRIs) - or counselling.

Using St John's Wort:
St John's Wort has been used since classical times for various ailments. It is thought to work in a similar way to SSRIs. Several reviews examining numerous trials have shown that St John's Wort is about twice as effective as a placebo in treating mild to moderate depression.

Trials also suggest it works equally well as some older tricyclic antidepressants for mild to moderate depression, with fewer side-effects. While data is limited, two recent trials show it is also as effective as SSRIs. Side-effects most commonly reported with St John's Wort include allergic reactions, restlessness and stomach upsets.

Risks:
since St John's Wort is unregulated in the UK, doses can vary. New evidence shows the remedy may have harmful interactions with some prescribed medicines. The Committee on the Safety of Medicines (CSM) has warned that St John's Wort may stop certain medicines working. It should not be taken if you are also taking oral contraceptives, warfarin (to prevent blood clots), cyclosporin (taken after transplants), digoxin (for heart conditions), theophylline (for asthma), indinavir (HIV treatment) or anti-convulsants (for epilepsy). The herb should not be taken with triptans (for migraine) as this may cause serious reactions. The CSM also warns that St John's Wort should not be taken if you are also taking SSRIs, because of a small risk that it may cause the potentially life-threatening serotonin syndrome. The CSM recommends talking to your doctor or pharmacist before using St John's Wort.

• What works? is based on reviews of the most up-to-date and reliable evidence available. It is written in collaboration with the NHS Centre for Reviews and Dissemination at York university (01904 433 634) and verified by experts. Details can be seen on the CRD website www.york.ac.uk/inst/crd

Thanks to guardian.co.uk who have provided this article. View the original here.