i dont see where it could hurt you, however i dont believe it will be much help either. diet pills generally only work when you are already on a strict low calorie diet which you obviously cannot be on if you want to bulk. i just started my clean bulk cycle and i just stick to complex carbs, plenty of protien, and absolutely no sugar. also if your worried about gaining unwanted fat, you can deffinently add some cardio to your routine a few days out of the week which will help alot.