If 20 mg feel better than 40 mg, don't take 40 mg. Why would you want to do more drugs and cause more harm if it doesn't feel as good? And by good do you mean it helps more with ADD or you just like how it feels? If you mean ADD, go with your doctor's dose, because he'll know how to treat your ADD better than you. If you care more about the other effects than helping with ADD tho, you should figure out your dose yourself, but keep in mind a higher dose is more dangerous and your doctor probably wouldn't give it to you. Too high of an amphetamine dose can be worse for your ADD than a smaller dose, but all other effects will be more effective at a higher dose. There are lots and lots of short-term side effects of adderall and vyvanse though, so too high of a dose will probably be unpleasant. These include anxiety, rapid thoughts, paranoia, rapid heart rate, energy, difficulty sleeping, loss of apatite, weight loss(directly, the loss of apatite is a different thing), dehydration, limbs "falling asleep", OCD-like symptoms, decreased sexual sensitivity, difficulty getting an erection, penis shrinkage and hardness while flaccid, difficulty urinating, and feeling lightheaded (I probably forgot a few too). So if your experiencing any of these and unsure why, it's probably the adderall and vyvanse, and you probably won't get them or they won't be too bad at 20 mg, which is another reason why a lower dose would be more pleasant. You really need to be careful with addiction if you don't have any other sources of adderall and vyvanse. If your doing double your prescribed dose, you'll run out before your next prescription, and if your addicted you'll go through withdrawal. The amount you're using is definitely dangerous for developing an addiction. Chances are you're already addicted. What you're doing is definitely not safe. Also, don't chew them, parachute them (the adderall, it doesn't work for vyvanse) (
http://www.bluelight.org/vb/threads/72622-Parachuting-Your-Pill-New-Method-of-Ingestion )
