from my experience, i am of the opinion that teething doesn't actually cause the fever, but it seems to lower their immune systems and i think they're more suceptible to whatever bug might be going around. i am a huge fan of infant tylenol, my son was born in the fall and his first winter we probably went through five or six doctors' visits, due to colds, ear infections, even pneumonia. the tylenol lowers the fever and for what it's worth, my son was always able to sleep at least a few hours after taking it. not to say just drug him up, but your dr. can probably tell you, if he's in obvious discomfort and has a fever it can't hurt.