Paxiled gave you the perfect answer.
It depends on the person, just as with meds. And don't necessarily expect taking 5-HTP by itself to work. It might or might not, but natural medicine usually combines several remedies until finding the right mix, or finding it doesn't work for you, and also generally works on diet, exercise, therapy, and relaxation exercises. It's not usually so simple as taking one thing. Natural medicine tries to get the whole body back into balance, if possible, not just work on one aspect, unlike allopathic medicine, which mainly treats symptoms, not causes.