St John Wort

Question 1

Depression

Answer 1

The only herbal remedy that has robust evidence to support its use in mild to moderate depression and dysthymia is Hypericum perforatum (St John’s Wort).

A Cochrane review of St John’s Wort found it to be more effective than placebo in the treatment of mild to moderate depression and as effective and better tolerated than standard antidepressants. It has also been shown to be as effective as tricyclic antidepressants in the treatment of mild-moderate depression. Its mechanism is thought to be similar to SSRIs (although noradrenaline uptake inhibition has also been demonstrated). NICE advise ‘may be of benefit in mild or moderate depression, but its use should not be prescribed or advised because of uncertainty about appropriate doses, variation in the nature of preparations, and potential serious interactions with other drugs’

It appears to have a similar profile of adverse effects in trials as placebo, but can cause serotonin syndrome. It is an inducer of P450 system, therefore decreased levels of drugs such as warfarin, ciclosporin. The effectiveness of the combined oral contraceptive pill may also be reduced.

Question 2

Anxiety

Answer 2

The only herbal remedy that is demonstrably effective in reducing anxiety is Piper methysticum (kava).

Despite this, kava cannot currently be recommended for clinical use because it has been associated with hepatotoxicity.