I wouldn't advise taking any PH or roid at 18. A top notch diet will blow your mind the results you get at your age. You owe it to yourself to try the diet route before you risk jacking up your jackstick among other things... You have enough Test naturally right now to blow the doors off of some over hyped crappy PH! Chances are you have never fed your body what it needs, even if you think you have. When you do you will know.