Focalin
"My 7.5 year old son has been taking 10mg Focalin for nearly a year.  Immediately it was a "miracle" for us.  He had good behavior marks in school, could finish his work and we were getting along better at home too.  About a month ago it seemed like maybe he had outgrown his dose, we upped it to 15mg.  Immediately again, great results.  But, we spent 4 hours in the ER tonight getting 2 EKGs & xrays because of his chest pains and irregular heartbeat.  Final diagnosis: stop taking Focalin.  As much as I loved the behavior and focus improvements he had from the drug, I love him more and can't risk damaging his heart."