i take adderal XR 20 mg. it will shrink your dick while you are on the pill. If i am not horny I will not be able to get an erection while on the pill. Try to do your exercises before taking it or after it wears off and you should be fine but having a bad flaccid while you are on the drugs will most definitely hurt your gains. Its a thin line you have to walk but Aderrall/concerta is an amazing drug so figure it out. Try horny goat weed.