Suggest Medication To Reduce Premature Greying Of Hair

Hi, I am 23 years old and have a lot of grey hair which is increasing rapidly. What can I do to reverse it and also arrest further greying? I've heard that PABA vitamins help in reversing but I don;t want to take it without consulting the specialists. What would you suggest? I really need help. Are these any medicines available or should I consult a specilaist doctor?