i will suggest you avoid any medicine. they all have side effects which can cause problems in later life. so i would definitely suggest against medicines.. i would suggest that you know that no habit can be stopped overnight. be it smoking, alcohol, or in your case masturbation probably. so dont try to stop all at once. it will not work. what you need to do is slow down gradually. make it alternate days, then twice a week, and then once , and then stop. use a calender. a gradual stop will help last longer. besides maintain a diary of things you have to do, or alternative options like sports or gym etc. the idea is that whenever the urge is too strong, and you have to avoid it, just get busy in these activities. i am sure this will help u best of luck