ICD-10-CM 2027
ICD-10 code for persistent pyrexia
From the official ICD-10-CM alphabetic index entry “Pyrexia (of unknown origin) › persistent”. Page updated September 29, 2026.
About coding persistent pyrexia
The ICD-10-CM code for persistent pyrexia is R50.9 (Fever, unspecified).
Within R50, choose R50.9 (Fever, unspecified) only when documentation doesn't support a more specific option: drug induced fever (R50.2) and other specified fever (R50.8).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 864 (Fever and Inflammatory Conditions, relative weight 0.8551), in MDC 18 (Infectious and Parasitic Diseases, Systemic or Unspecified Sites), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about persistent pyrexia ICD-10 codes
What is the ICD-10 code for persistent pyrexia?
- R50.9 — Fever, unspecified.
Is R50.9 billable?
- Yes. R50.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can R50.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict R50.9 as a principal diagnosis.
Is R50.9 a CC or MCC?
- No. R50.9 is neither a CC nor an MCC under MS-DRG v44.0.