Allegedly fever reducers help the symptoms without stopping the good that fevers do. Not sure how to be honest but that's what I've read. I try to only give them when the fever is high and she is uncomfortable. Since this is the first one she's had you might want to call your ped. Although since she's happy and playing I'd probably give it 24 hours and see where she is. If you have to keep giving her fever reducer during that time to keep her happy and playing, I would definitely call.