R50.9 Fever, unspecified
Billable ICD-10-CM code, FY2026.
Applicable to
- Fever NOS
- Fever of unknown origin [FUO]
- Fever with chills
- Fever with rigors
- Hyperpyrexia NOS
- Persistent fever
- Pyrexia NOS
Applies from R50 Fever of other and unknown origin
Excludes1 (never code together)
- chills without fever (R68.83)
- febrile convulsions (R56.0-)
- fever of unknown origin during labor (O75.2)
- fever of unknown origin in newborn (P81.9)
- hypothermia due to illness (R68.0)
- malignant hyperthermia due to anesthesia (T88.3)
- puerperal pyrexia NOS (O86.4)
MS-DRG index
Defines the logic of DRG(s) 864 in MDC 18.
Approximate ICD-9-CM (GEMs)
780.60 Fever, unspecified (approximate)
Code annotations containing back-references to R50.9
Back-references to R50.9
- Type 1 Excludes:
R68.83 Chills (without fever) ("chills with fever (R50.9)")
Diagnosis Index entries for R50.9
- Chill (s) › with fever
- Elevated, elevation › body temperature (of unknown origin)
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › ephemeral (of unknown origin)
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › intermittent (bilious) › of unknown origin
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › persistent (of unknown origin)
- Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › unknown origin
- FUO (fever of unknown origin)
- High › temperature (of unknown origin)
- Hyperpyrexia
- Hyperpyrexia › unknown origin
- Inanition › fever
- PUO (pyrexia of unknown origin)
- Pyrexia (of unknown origin)
- Pyrexia (of unknown origin) › persistent
- Rigors › with fever
- Temperature › body, high (of unknown origin)
Nearby codes
R50.8 Other specified feverR50.81 Fever presenting with conditions classified elsewhereR50.82 Postprocedural feverR50.83 Postvaccination feverR50.84 Febrile nonhemolytic transfusion reactionR50.9 Fever, unspecified (this code)