St. John’s wort was traditionally used as a calming tonic, a favourite in the menopause, for psychological and neurological conditions, and externally for wound healing and burns. However the vast quantity of modern research into St. John’s wort has addressed only its use in depression. Clinical studies, although of variable quality, have shown that St. John’s wort is an effective treatment, comparable with and better tolerated than conventional antidepressants, in cases of mild to moderate depression. It may interact with other medicines, reducing the effect of immuno-suppressant drugs, anti-HIV drugs chemotherapy, blood thinning drugs and digoxin.