Jul 27, · But, when an adult's temperature begins to spike at degrees F and above, Banner Health reports, that there may be a cause for concern. Duration of Fever Danger A spiking fever can . Mar 30, · Usually, a body temperature above F is considered elevated. However, a fever isn’t considered significant until it reaches about F. How high of a fever is dangerous for adults? Another below F .
When to Seek Help for a Fever | UPMC HealthBeat. Sep 17, · Adults typically have a fever if their body temperature increases to °F (38°C). This is called a low grade fever. A high grade fever happens when your body temperature is °F (°C) or.