Fever ICD-10-CM codes

R50.9 (fever, unspecified) covers fever NOS, fever of unknown origin, persistent fever, and hyperpyrexia. R50.2 is drug-induced fever, reported with the T36 to T50 adverse effect code. R50.81 is fever presenting with conditions classified elsewhere, used when the provider documents the fever as significant alongside a condition that does not itself imply fever, such as sickle-cell disease or leukemia; the underlying condition is coded first. R50.82 is postprocedural fever, R50.83 postvaccination fever, and R50.84 febrile nonhemolytic transfusion reaction.

Fever is integral to infection. When pneumonia, urinary tract infection, sepsis (A41.9), or another infection is confirmed, the fever is not coded separately. Chills without fever are R68.83, and a febrile seizure is R56.00. Heat-related hyperthermia is coded to T67, not R50.

In the outpatient setting a workup that ends with only a suspected source is coded R50.9 plus any other documented symptoms. Fever in a newborn is coded from chapter 16 or the appropriate perinatal category rather than R50.9 when the provider documents a perinatal cause.