vyvanse gave me more negative effects than dexedrine as well. insanely dry mouth, nausea, paranoid anxiety, and didnt even help me focus. the crash started two hours after ingestion, and gradually came down for about 12 more hours, and it wasnt recreational or even therapeutic in any way for me. dexedrine is a smooth ride for me, and the comedown is barely noticeable, i get no nausea or dry mouth, it works great for ADD, and its very recreational. desoxyn worked the way i expected vyvanse to work: long lasting, more euphoric, stronger, and a less "dirty" version of dexedrine. i dont know why, but i reacted the same way as you did. it might be the longer duration that lets the side effects keep getting stronger throughout the 14 hours, unlike dexedrine, which starts to wear off after 90 minutes of feeling effects, and the side effects stops increasing after that time, and quickly wear off until they are merely residual effects, and are usually not significantly uncomfortable. thus being unable to develop side effects as noticable as the ones while on vyvanse. having said that, desoxyn lasts a solid 8-10 hours, and has less side effects than any other med. also there might be something thats going on with the way its absorbed and released into your liver, like maybe your digestive system doesnt react well to the process of converting the l-d-amp into d-amp to get released into the liver. or maybe the lisdexamp gets kinda dirty when it turns into d-amp, and doesnt convert well, thus giving a less pure feeling, and having more side effects. this isnt based on any fact, im just theorizing, cause im curious to know this as well. desoxyn is what vyvanse was supposed to be, and is the most effective ADD med, as well as the most recreational, and within prescribed doses, the safest. id stick with dex for now, maybe try an ER formulation of dexedrine to extend the duration while still getting the clean dexedrine feeling and none of the vyvanse side effects.