Stephnie 803 Views July 14, 2017, 09:42:11 AM Question Solved Share Tweet Fever of unknown origin (FUO) is characterized by a fever of ____° F or greater. What will be an ideal response? Lydia July 14, 2017, 09:56:04 AM #1 Answer ANS: 101 FUO is a fever of greater than 38.3° C (101° F) that remains undiagnosed after 3 days of hospital investigation or three or more outpatient visits. Adrian July 14, 2017, 10:06:17 AM #2 This site is amazing.