Does the herbal preparation St. John's wort help with depression?

Possibly the herbal preparation St. John's wort helps with mild and moderate depression. However, it has not been proven to be effective for severe depression. St. John's wort also has to be taken in adequate doses and although it is considered to be well tolerated, it is not free of side effects and above all of interactions with other preparations (e.g. reducing the effect of the contraceptive pill).