ICD-10-CM 2027
ICD-10 code for Hyperpyrexia
From the official ICD-10-CM alphabetic index entry “Hyperpyrexia”. Page updated September 29, 2026.
About coding Hyperpyrexia
The ICD-10-CM code for Hyperpyrexia is R50.9 (Fever, unspecified). The official index lists 3 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on R50.9.
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.
More specific Hyperpyrexia codes (official index)
Common questions about Hyperpyrexia ICD-10 codes
What is the ICD-10 code for Hyperpyrexia?
- R50.9 — Fever, unspecified. More specific codes apply when the documentation supports them: T67.01, T88.3, R50.9.
What is the ICD-10 code for heat hyperpyrexia?
- T67.01 — Heatstroke and sunstroke (header code; choose a more specific subcode).
What is the ICD-10 code for unknown origin hyperpyrexia?
- 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.