Atropine is an anticholinergic agent that can activate the autonomous sympathetic nervous systems. The symptoms mnemonic would be hot as a hare(hyperthermia), blind as a bat(pupil mydriasis), dry as a bone(no sweat), red as a beet(vasodilatation), and mad as a hatter(delirium), stuffed as a pipe(urinary retention)
But the one that life-threatening and needs to be anticipated would be arrhythmia(which can cause cardiac arrest) and seizure