2026 ICD-10-CM Diagnosis Code R50.83Postvaccination fever

ICD-10-CM Codes›R00–R99›R50-R69›R50

ICD-10-CM R50.83
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R50.83 is a billable ICD-10-CM diagnosis code for postvaccination fever. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. Coders also document this condition as adverse reaction to pertussis vaccine. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Fever.

Code Identity

ICD-10-CM Code
R50.83
Billable Status
Yes — Valid for Submission
Code Describes
Postvaccination fever
Short Description
Postvaccination fever
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 CodeR50.83Postvaccination fever

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adverse reaction to pertussis vaccine
  • Fever caused by diphtheria vaccine
  • Fever caused by pertussis vaccine
  • Fever caused by tetanus vaccine
  • Fever caused by vaccine
  • Fever caused by vaccine product containing only Bordetella pertussis and Clostridium tetani and Corynebacterium diphtheriae antigens

Tabular List NotesGuidance

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

Inclusion Terms

  • Postimmunization fever

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)
      • postimmunization
    • Fever(inanition) (of unknown origin) (persistent) (with chills) (with rigor)
      • postvaccination

Clinical ClassificationClinical

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

CCSR SYM002
Fever
Default principal diagnosis: inpatient Yes · outpatient Yes

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 R50.83 to ICD-9-CMHistory

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

ICD-9-CM
780.63 Postvaccination fever
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 R50.83Overview

Is R50.83 (Other specified fever) a billable code?

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

Can R50.83 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the postvaccination fever is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R50.83?

Under the General Equivalence Mappings, postvaccination fever converts to ICD-9-CM 780.63 (postvaccination fever). 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.