My 10 yr old son just started 20mg Vyvanse a week ago. He was just finally diagnosed with ADHD about a month ago. The first couple of days, the med seemed to be helping EXCEPT ,even though his behavior had calmed, he started talking excessively! Worse than before! Well now the med seems to wear off with about 5 or 6 hours and he becomes a totally different child! He yells, screams, cries, becomes extremely defiant, goes into rages over the smallest things, and these are all extremely worse than before he started taking this medication. We go back to see his Dr next week to assess his progress but I don't think I can handle this behavior that long!! After 5 or 6 hours, my baby boy is not even a child I recognize!! The changes are so drastic that he doesn't even seem like MY son!!!