"it&#039;s the only add med that actually works for me. the higher the dose the clearer i think (male 5&#039;11 185). however, if my dose is over 40mg (i&#039;ve taken as much as a 100mg) then i get erectile dysfunction, penis shrinkage and dry mouth. once i lowered my dose to 40mg i stopped concentrating as good but the side effects went away too."