ICD-10-CM R50: Fever of other and unknown origin

ICD-10-CM Diagnosis Code (2025)

Official Description for R50

Fever of other and unknown origin

Coding Notes & Guidelines for R50

Excludes1: Not Coded Here
  • 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)
Excludes1: Not Coded Here

postvaccination (postimmunization) fever (R50.83)

Excludes1: Not Coded Here
  • postprocedural infection (T81.4-)
  • posttransfusion fever (R50.84)
  • postvaccination (postimmunization) fever (R50.83)
Code First
  • underlying condition when associated fever is present, such as with:
  • leukemia (C91-C95)
  • neutropenia (D70.-)
  • sickle-cell disease (D57.-)
Use Additional Code

code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)

Inclusion Terms

Postimmunization fever

Inclusion Terms
  • FNHTR
  • Posttransfusion fever
Inclusion Terms
  • Fever NOS
  • Fever of unknown origin [FUO]
  • Fever with chills
  • Fever with rigors
  • Hyperpyrexia NOS
  • Persistent fever
  • Pyrexia NOS

Child Codes (More Specific Codes for R50):

R50.2 - Drug induced fever R50.8 - Other specified fever R50.81 - Fever presenting with conditions classified elsewhere R50.82 - Postprocedural fever R50.83 - Postvaccination fever R50.84 - Febrile nonhemolytic transfusion reaction R50.9 - Fever, unspecified

About ICD-10-CM Code R50 (Fever of other and unknown origin)

ICD-10-CM code R50 is a billable or specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. The 2025 edition of ICD-10-CM R50 became effective on October 1, 2024.

This page provides detailed information about R50 - Fever of other and unknown origin. It includes common terminology, coding guidelines such as "Includes," "Excludes1," and "Excludes2" notes, and information on required 7th characters. Utilizing this information correctly is essential for accurate medical coding and claims submission for conditions like Fever of other and unknown origin.