Ds1 (5.9) has had a fever of over 40 (mostly aroind 40.6 - 40.8) for 36 hours now. It comes down with calpol and nurofen but he's SO sick. Doctor said it's just a virus and to ride it out but bless him. He is prone to fevers this high but never for this long.
My younger boy has never ever had a fever this high so I'd panic if it were him!