My 10-year-old son has started on Vyvanse 20 mg last Sunday. He has been on it for 5 days now. His teacher has had nothing but good things to say about him in school this week. It is a welcome change after a year of trial and error in finding the right med. He has tried Adderall, Concerta, and Strattera. The first two did well the first week, and than dropped off, so we are hoping that this one will last. My question is how long does it usually last in your experience? I read that it typically lasts for 12-14 hours, but I noticed with him it is about 7. It gets him through school so far, but I have a hard time getting him through his homework at home. I know this is the lowest dose, and was thinking of asking his psychiatrist if he would benefit from an afternoon dose. Any suggestions on this? He has not shown any side affects so far. His appetite is fine and he is sleeping fine. Just wish it lasted a little longer.