"i am 17 years old, i&#039;ve always had a problem focusing in school. eventually i was taken to get tested and i did in fact have a.d.d . my doctor started me on 50mg of vyvanse. my first day taking the pill was amazing and so was that whole 2 weeks. its now my third week on vyvanse and i&#039;ve been having rapid heart rates, blurred vision, and feeling very jittery/shaky. i&#039;m curious if my dosage is too high for me. i&#039;m also afraid that if i get my dosage lower that it will no longer work for me. "