R50: Fever of other and unknown origin

Fever of other and unknown origin categorizes fevers that aren't immediately attributable to known causes, typically following initial medical examination or assessment. These fevers can result from a wide variety of conditions, notably including infections, cancers, autoimmune diseases, and various inflammatory conditions. Transmission methods vary depending on the specific underlying cause, and as such, these fevers don't follow a uniform pattern of spread or disease progression. Common symptoms for these fevers generally include a body temperature above 100.4 degrees Fahrenheit or 38 degrees Celsius, sweating, chills, headaches, muscle aches, and weakness. It's important to note that these fevers can affect multiple body systems simultaneously or sequentially, especially when they're associated with systemic illnesses. While these fevers can sometimes resolve spontaneously, a persistent fever of unknown origin can signal a potentially serious condition and may warrant further medical investigation.