Dear Doctor, My Mother Is Suffering From Fever, Temp Goes

dear doctor, my mother is suffering from fever, temp goes upto 100.4 deg F, Febrex Plus 500 mg at interval of 5 hrs is being administered (on advice of medical practitioner). Till now 20 Tablet of 500mg is given, Temperature remains 97 to 98.8 deg F. But in last 20 hrs after 1 hrs of taking febrex plus temp rises to 100.4 deg. is it normal?