St John's wort (hypericum perforatum) is a herb that is sometimes used to treat mild to moderate depression. Research suggests that St John's wort can be as effective as standard antidepressants and has fewer side effects.
NICE guidelines do not recommend St John's wort. This is based on concerns about how much you should take, the variation in contents of products and the serious problems it can cause if you are also taking other drugs. Of the drugs sometimes used to treat multiple sclerosis, you shouldn't take St John's wort if you are also taking amitriptyline, carbamazepine, imipramine, phenytoin, nortriptyline, phenobarbital or primidone. St John's wort can also reduce the effects of the blood thinning drug warfarin and of oral contraceptives.
If you are taking St John's wort, it is important to tell the health professionals who are treating you.