2026 ICD-10-CM Diagnosis Code R50.81Fever presenting with conditions classified elsewhere

ICD-10-CM Codes›R00–R99›R50-R69›R50

ICD-10-CM R50.81
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R50.81 is a billable ICD-10-CM diagnosis code for fever presenting with conditions classified elsewhere. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is a manifestation code that cannot be reported as the principal diagnosis. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fever.

Code Identity

ICD-10-CM Code
R50.81
Billable Status
Yes — Valid for Submission
Code Describes
Fever presenting with conditions classified elsewhere
Short Description
Fever presenting with conditions classified elsewhere
Same as the full description in the CMS dataset.
Parent Code
R50.8
Other specified fever

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR50-R69General symptoms and signs
CategoryR50Fever of other and unknown origin
This CodeR50.81Fever presenting with conditions classified elsewhere

Code EditsBilling

Medicare Code Editor checks that affect claim validity for R50.81.

Manifestation diagnoses
Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and therefore should not be used as a principal diagnosis.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute hepatic failure
  • Anasarca
  • Brass-founders' fever
  • Copper fever
  • COVID-19
  • Double quotidien fever
  • Febrile granulocytopenia
  • Febrile leukopenia
  • Febrile neutropenia
  • Fever caused by SARS-CoV-2
  • Fever-associated acute infantile liver failure syndrome
  • Granulocytopenic disorder
  • Intermittent fever
  • Intermittent hepatic fever
  • Malarial fever
  • Malignant tertian fever
  • Metal fever
  • Paraneoplastic fever
  • Polymer fume fever
  • Quartan fever
  • Quotidien fever
  • TAFRO syndrome
  • Tertian fever
  • Toxic inhalation-induced febrile illness

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Code First

  • underlying condition when associated fever is present, such as with:
  • leukemia C91 C95
  • neutropenia D70
  • sickle-cell disease D57

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • due to
        • conditions classified elsewhere
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • presenting with conditions classified elsewhere

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM002
Fever
Default principal diagnosis: inpatient No · outpatient No

Clinical InformationClinical

  • Chemotherapy-Induced Febrile Neutropenia

    fever accompanied by a significant reduction in neutrophil count associated with chemotherapy.

  • Febrile Neutropenia

    fever accompanied by a significant reduction in the number of neutrophils.

  • Neutrophils

    granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.

  • Anasarca

    a condition that is characterized by the presence of generalized edema. causes include congestive heart failure, liver failure, renal failure, and severe malnutrition.

Patient EducationClinical

Fever

A fever is a body temperature that is higher than normal. A normal temperature can vary from person to person, but it is usually around 98.6 °F (37 °C). A fever is not a disease. It is usually a sign that your body is trying to fight an illness or infection.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert R50.81 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
780.61 Fever in other diseases
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R50.81Overview

Is R50.81 (Other specified fever) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report fever presenting with conditions classified elsewhere on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can R50.81 be a principal diagnosis?

No. This is a manifestation code: fever presenting with conditions classified elsewhere describes the manifestation of an underlying disease rather than the disease itself, so the underlying condition is sequenced first.

What is the ICD-9 equivalent of R50.81?

Under the General Equivalence Mappings, fever presenting with conditions classified elsewhere converts to ICD-9-CM 780.61 (fever in other diseases). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.