How severe does a fever have to get in a teen for them to get to the hospital?

Treat the number?: Criteria for hospital admission isn't based on a fever alone. A fever without the clinical context, is like a fish out of water. Normal body temperature is 98.6f or 37 c. A low grade fever is 100.4f while a high grade fever is 101.4f and above. More important than the fever are your teen's symptoms. Regardless, an evaluation by a healthcare professional is warranted.