Dexedrine (generically known as Dextro-amphetamine) is the best stimulant medication for ADD. I have tried Concerta, Ritalin, Adderall, Adderall XR, and Dexedrine. Ritalin was not strong enough and both preparations of Adderall caused too much PNS stimulation (muscle tremors, jitteriness, etc) because I need a very high dose. Dexedrine was as effective as the Adderall was, but even at my high dose, it does not cause unwanted PNS stimulation. I believe that the difference between Adderall (mixed amphetamine salts) and Dexedrine (dextroamphetamine), is that Dexedrine is pure dextroamphetamine, whereas Adderall is 7.5 dextroamphetamine and 2.5 levoamphetamine. Levoamphetamine is mainly a Peripheral nervous system (PNS) stimulant, where as Dextroamphetamine is mostly a Central Nervous System (CNS) stimulant. At low doses, Levoamphetamine can augment the help that the dextroamphetamine gives, but at higher doses it causes side effecxts that are self defeating. Because I was taking 30mg adderall three times a day, I was consumine too much L-amphetamine in order to get enough D-amphetamine. I now take 25mg Dexedrine and am doing great.