I deleted the comment because I realised I didn't really want to get into a medical debate - I don't have much authority on the subject myself. But, alas I must pursue
I'm well aware the label on Jack3d recommends for 18 years and over. It's primary ingredient is 1-3 diethylamylamine, an ingredient I am well versed in - and personally I find it much cleaner and effective then caffeine. There is no crash, no jitters (for me, although it effects people differently) and I wouldn't consider it "more energy" but rather a different, consistent, calm energy. 1-3 diethylamylamine is probably the greatest thing since ephedra. It has somehow managed to stay low-key in the eyes of lawmakers and authorities. If/When Today Tonight decides to run the story, inevitably one of their key points will be "KIDS AS YOUNG AS 12 ARE GETTING HIGH OFF THIS". Jack3d needs to have that label to cover its own arse - not because of any specific medical findings. Certainly it can be said of any psychoactive substance, including coffee that the younger you are, the more susceptible you are to its effects but the distinction is not black and white - at 16, you are old enough to work it out yourself. The poster found the effects uncomfortable, strong - he needs to read up about the product and cease use or reduce dosage, not merely take advice from the packaging, positive or negative. At 18, the same decision making processes need to be in play.