Version 2024
No Valid Principal Dx

2024 ICD-10-CM Diagnosis Code R50.81

Fever presenting with conditions classified elsewhere

ICD-10-CM Code:
ICD-10 Code for:
Fever presenting with conditions classified elsewhere
Is Billable?
Yes - Valid for Submission
Chronic Condition Indicator: [1]
Not chronic
Code Navigator:

Code Classification

  • Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
    • General symptoms and signs
      • Fever of other and unknown origin

R50.81 is a billable diagnosis code used to specify a medical diagnosis of fever presenting with conditions classified elsewhere. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2023 through September 30, 2024.

According to ICD-10-CM guidelines this code should not to be used as a principal diagnosis code when a related definitive diagnosis has been established.

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

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

Clinical Classification

Clinical Information

  • 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.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.

Code First

Code First
Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.
  • underlying condition when associated fever is present, such as with:
  • leukemia C91 C95
  • neutropenia D70
  • sickle-cell disease D57

Index to Diseases and Injuries References

The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).

Code Edits

The Medicare Code Editor (MCE) detects and reports errors in the coding of claims data. The following ICD-10-CM Code Edits are applicable to this code:

  • 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.

Convert R50.81 to ICD-9-CM

  • ICD-9-CM Code: 780.61 - Fever in other diseases

Patient Education


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.

Infections cause most fevers. You get a fever because your body is trying to kill the virus or bacteria that caused the infection. Most of those bacteria and viruses do well when your body is at your normal temperature. But if you have a fever, it is harder for them to survive. Fever also activates your body's immune system.

Other causes of fevers include:

  • Medicines, including some antibiotics, blood pressure medicines, and anti-seizure medicines
  • Heat illness
  • Cancers
  • Autoimmune diseases
  • Some childhood vaccines

Treatment depends on the cause of your fever. If the fever is very high, your health care provider may recommend taking an over-the-counter medicine such as acetaminophen or ibuprofen. Adults can also take aspirin, but children with fevers should not take aspirin. It is also important to drink enough liquids, to prevent dehydration.

[Learn More in MedlinePlus]

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.


[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.