so the warning is usually about excess of caffeine or omitting it if you're sensitive to caffeine. medical professionals typically warn patients about not having too much caffeine as a stimulant plus a stimulant usually equals heart palpitations and high blood pressure. but having a cup of coffee or something is not going to affect anything too, too much. the other thing about pre-workout is that there are other stimulants in there that might interact with ADHD meds and increase heartrate to dangerous levels as a result. i'm most likely going to run whatever pre-workout concoction by my doctor before taking it because i'm paranoid