My son is 5.5 yrs old, and we just started vyvanse. However he can't swallow pills yet, so I was told I could open it up and mix the med in with water, well one day last week while at school the teachers said his heart was beating like out of his chest, now I'm worried my sons going to die of a heart attack or something. But without the med his ADHD & behavior is wayyy over the top, with the vyvanse he was very well behaved & his ADHD was 100% controlled, but this rapid heartbeat scares me. I looked up side effects and cardiovascular effects and it said sudden death as a side effect. So yeah I'm freaked out, HELPPPP,