Even though a body temperature of 109 degrees Fahrenheit is theoretically attainable for humans, there are specific situations where this could be fatal. According to U.S. Pharmacist, drug-induced fevers can occasionally reach 109 F, however 102–104 F temps are more frequent.
In an August 2008 event, a high school football player passed away from heat stroke, according to a Fox News article. The player most likely had a fever of 109 F when he collapsed, according to a heat stroke expert featured in the report. A prolonged fever of more than 105 degrees Fahrenheit can have negative effects. According to a U.S. Pharmacist, infections are frequently warded off by fevers between 100 and 104 degrees Fahrenheit.