Over 38.5 is a significant fever, although fever in itself is not dangerous. It's a sign that his body is fighting an infection of some sort. Most of the time it's a viral thing. Unless your bubs is under 3 months I wouldn't worry about that temp in itself. I'd be more looking at how your bubs is. Most importantly is his feeding, in particular his fluid intake. Make sure he is still having good numbers of wet nappies, His mouth and tongue are nice and moist and if he cries he's still producing tears. Very important to make sure he doesn't get dehydrated. He won't be his usual self with that fever and he won't want to play etc but make sure he isn't too drowsy, hard to rouse. If you have any doubts at all get him checked out. Remember most Paeds Emerg departments can give you a bit of over the phone advice if you're worried. It sounds like he's just picked up a viral thing. We usually advise giving panadol only if he seems bothered or upset by the fever or if he also seems to be in pain.