My difficult child is on Vyvanse for ADHD. He has been taking it for a week and a half. I am already seeing an improvement in his behavior at home and at school. He has been getting all greens --which is good--on his behavior chart and I am shocked to say the least that this has happened so quickly. I am curious if this is normal for an ADHD medication to take effect so quickly? I expected to wait at least a month for it to take effect. His defiance has dramatically improved and he is now more -pardon the expression-"normal" in the way that he reacts to discipline. He used to throw himself in the floor in anger or say rude and inappropriate words and now he just still gets agitated slightly but accepts it and goes on instead of freaking out every time. I wonder why this medicine helps with the defiance also. Was his brain just mis-firing all this time? Anyone else have any concerns or info about taking a 12 hour medication for ADHD? I really just wanted to get him through the school day; but I am not the doctor or the expert on medications. Thanks in advance.