This is my 3rd month on Vyvanse. 1st wk on 40mg. I was on 30mg prior. I feel fine for the first 2-3hrs after I take it. If anything I tend to hyperfocus on things and have to make myself switch tasks. However around the 3-4hr mark my heart starts pounding, head starts feeling foggy, face tingles, vision gets super blurry, I lose all motivation and get irritable. I have taken my blood pressure multiple times during that period and it's perfect. Pulse is a little high between 80-90 but not concerning. I freak out that I'm having a stroke, HA or am going to faint or have a seizure. That of course only makes it worse. It is debilitating when I hit that mark. I have take Ritalin and Adderall.Any suggestions?