Saint John's wort

Last reviewed 01/2018

Extracts of the plant Hypericum perforatum (St John's wort) are widely used as herbal remedies for depression

• the pharmacologically active constituents have not been precisely identified (1)
• Hypericum is unlicensed as a medicine in the UK, but can be bought from pharmacies, supermarkets and health food shops.

The use of St John's wort (Hypericum perforatum) extract in the treatment of depression has been reviewed by Linde and Mulrow (2).

• a meta-analysis of 27 trials comparing St John's wort with either placebo or active treatments was undertaken
• this analysis suggests that St. John's wort is more effective than placebo and is as effective as low-dose tricyclic antidepressants (TCAs) as an antidepressant therapy
• the mechanism of action appears to be the inhibition of the reuptake of noramines
• no long-term efficacy and safety data are available on use of hypericum

Subsequent randomised placebo-controlled studies have yielded conflicting results

• Hypericum gave benefit (matching that of imipramine) in an 8-week study in general practice patients with mild or moderate depression, present, on average, for less than 6 month (3)
• by contrast, it was no more effective than placebo in two large studies conducted in the USA in outpatients with similarly severe, but more longstanding, major depression (4,5)

Therefore there is evidence supporting the use of St John's wort as a therapeutic option for treating depression although, when used in the treatment of longstanding, major depression, St John's wort was no more effective than placebo.

NICE guidance concerning the use of St John's wort in depression states (6):

• although there is evidence that St John's wort may be of benefit in mild or moderate depression, healthcare professionals should not prescribe or advise its use by patients because of uncertainty about appropriate doses, variation in the nature of preparations and potential serious interactions with other drugs (including oral contraceptives, anticoagulants and anticonvulsants)
• patients who are taking St John's wort should be informed of the different potencies of the preparations available and the uncertainty that arises from this. They should also be informed of the potential serious interactions of St John's wort with other drugs (including oral contraceptives, anticoagulants and anticonvulsants

Reference:

1. Drug and Therapeutics Bulletin (2003); 41 (8): 63.
2. Evidence Based Medicine (1999); 4(3): 82.
3. Phillipp M et al. Hypericum extract versus imipramine or placebo in patients with moderate depression: randomised multicentre study of treatment for eight weeks. BMJ 1999; 319: 1534-9.
4. Shelton RC et al. Effectiveness of St John's wort in major depression. A randomized controlled trial. JAMA 2001; 285: 1978-86.
5. Hypericum Depression Trial Study Group. Effect of Hypericum perforatum (St John's wort) in major depressive disorder. JAMA 2002; 287: 1807-14.
6. NICE (December 2004). Management of depression in primary and secondary care