but I do know that fevers left untreated in children (well anyone really) is extremely dangerous.
Yes, I know. I should have clarified that their fevers spiked every few hours when the Motrin wore off. More Motrin and the fevers went down again until it wore off again. For the one who didn't get antibiotics - his fever went away the evening he was refused the second time. He and his sister are still coughing, though (she had strep throat and got antibiotics for that immediately).
But what I was trying to figure out was whether antibiotics would do any good for a fever caused by a virus. I didn't think they would, but not my area of expertise.