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v1.0.0
ICD-10 Guide
DiagnosesFever

Fever

ICD-10 Coding for Fever(R50.9, R50.81)

PRIMARY SPECIALTYEmergency Medicine
COMPLEXITYHigh
LAST UPDATED09/15/2025
Sam Tuffun, PT, DPT
Physical Therapist | Medical Coding & Billing Contributor

Diagnosis Overview

What is Fever?
Essential facts and insights about Fever

Key Clinical Considerations:

  • Elevated body temperature (≥100.4°F or 38°C)
  • Chills, sweating, malaise, headache
  • Tachycardia, tachypnea, altered mental status

Clinical Information

Clinical Criteria & Documentation Requirements

  • Patient's temperature readings and duration of fever
  • Associated symptoms and clinical history
  • Physical exam findings related to fever

Coding Guidelines

Usage Guidelines & Examples

  • Use R50.9 for unspecified fever; R50.81 for fever with known conditions.
  • Common errors include misclassifying fever as a symptom rather than a diagnosis.

Code Exclusions

Important Exclusions

  • Fever due to neoplasm (C80.1)
  • Fever due to infectious diseases (A00-B99)

Related ICD-10 Codes

Primary Codes
R50.9
Fever, unspecified
R50.81
Fever presenting with conditions classified elsewhere
Ancillary Codes
R50.2
Differential Codes
R50.81
R50.9
R50.9
when no cause is identified.

Related CPT Codes

CPT codes will be available in a future update.

Specialty Focus

Primary Specialty

Emergency Medicine

Specialty Applications

  • Pediatric and adult populations
  • Emergency departments, urgent care settings

Coding Complexity

High Complexity

This diagnosis requires careful attention to:

  • Comprehensive clinical documentation
  • Accurate code selection based on clinical criteria
  • Proper exclusion considerations
  • Specialty-specific coding guidelines

Documentation

Documentation Templates

Billing Information

Billing Considerations

  • Ensure proper documentation for billing
  • Verify code specificity requirements
  • Check for any additional codes needed
  • Review payer-specific guidelines

Common Issues

  • Insufficient clinical documentation
  • Incorrect code selection
  • Missing supporting diagnoses
  • Timing and frequency documentation

Frequently Asked Questions

Documentation requirements?

Document the patient's temperature, duration of fever, and associated symptoms.

Billing considerations?

Ensure accurate coding to reflect the underlying cause of fever when known.