ICD-10-CM
ICD-10 code for Fever of unknown origin: R50.9
The CDC title for "Fever of unknown origin" is R50 (Fever of other and unknown origin), a header that is not billable. When nothing more specific is documented, the billable code is R50.9, Fever, unspecified.
Source: CDC ICD-10-CM FY2027 order file dated June 16, 2026. Publisher page
Run it in Rivvi
Check every code on your export
Upload a claims or problem-list export. Rivvi flags codes that are not billable, replaced, or unspecified when a specific code exists.
Check my exportFree to start. Opens Rivvi, the AI workspace for healthcare teams.
Codes under R50, then other CDC titles that name fever
A header groups codes and is not billed. A billable code is one you can report.
- R50Fever of other and unknown originHeader
- R50.2Drug induced feverBillable
- R50.8Other specified feverHeader
- R50.81Fever presenting with conditions classified elsewhereBillable
- R50.82Postprocedural feverBillable
- R50.83Postvaccination feverBillable
- R50.84Febrile nonhemolytic transfusion reactionBillable
- R50.9Fever, unspecifiedBillable
- A01Typhoid and paratyphoid feversHeader
- A01.0Typhoid feverHeader
- A01.00Typhoid fever, unspecifiedBillable
- A01.02Typhoid fever with heart involvementBillable
- A01.09Typhoid fever with other complicationsBillable
- A01.1Paratyphoid fever ABillable
- A01.2Paratyphoid fever BBillable
- A01.3Paratyphoid fever CBillable
- A01.4Paratyphoid fever, unspecifiedBillable
- A25Rat-bite feversHeader
- A25.9Rat-bite fever, unspecifiedBillable
- A38Scarlet feverHeader
- A38.0Scarlet fever with otitis mediaBillable
- A38.1Scarlet fever with myocarditisBillable
- A38.8Scarlet fever with other complicationsBillable
- A38.9Scarlet fever, uncomplicatedBillable
- A48.2Nonpneumonic Legionnaires' disease [Pontiac fever]Billable
- A48.4Brazilian purpuric feverBillable
- A68Relapsing feversHeader
- A68.0Louse-borne relapsing feverBillable
- A68.1Tick-borne relapsing feverBillable
- A68.9Relapsing fever, unspecifiedBillable
- A75Typhus feverHeader
- A75.0Epidemic louse-borne typhus fever due to Rickettsia prowazekiiBillable
- A75.2Typhus fever due to Rickettsia typhiBillable
- A75.3Typhus fever due to Rickettsia tsutsugamushiBillable
- A75.9Typhus fever, unspecifiedBillable
- A77Spotted fever [tick-borne rickettsioses]Header
- A77.0Spotted fever due to Rickettsia rickettsiiBillable
- A77.1Spotted fever due to Rickettsia conoriiBillable
- A77.2Spotted fever due to Rickettsia sibericaBillable
- A77.3Spotted fever due to Rickettsia australisBillable
- A77.8Other spotted feversBillable
- A77.9Spotted fever, unspecifiedBillable
- A78Q feverBillable
- A79.0Trench feverBillable
- A88.0Enteroviral exanthematous fever [Boston exanthem]Billable
- A90Dengue fever [classical dengue]Billable
- A91Dengue hemorrhagic feverBillable
- A92Other mosquito-borne viral feversHeader
- A92.1O'nyong-nyong feverBillable
- A92.2Venezuelan equine feverBillable
- A92.4Rift Valley feverBillable
- A92.8Other specified mosquito-borne viral feversBillable
- A92.9Mosquito-borne viral fever, unspecifiedBillable
- A93Other arthropod-borne viral fevers, not elsewhere classifiedHeader
- A93.1Sandfly feverBillable
- A93.2Colorado tick feverBillable
- A93.8Other specified arthropod-borne viral feversBillable
- A94Unspecified arthropod-borne viral feverBillable
- A95Yellow feverHeader
- A95.0Sylvatic yellow feverBillable
- A95.1Urban yellow feverBillable
- A95.9Yellow fever, unspecifiedBillable
- A96Arenaviral hemorrhagic feverHeader
- A96.0Junin hemorrhagic feverBillable
- A96.1Machupo hemorrhagic feverBillable
- A96.2Lassa feverBillable
- A96.8Other arenaviral hemorrhagic feversBillable
- A96.9Arenaviral hemorrhagic fever, unspecifiedBillable
- A98Other viral hemorrhagic fevers, not elsewhere classifiedHeader
- A98.0Crimean-Congo hemorrhagic feverBillable
- A98.1Omsk hemorrhagic feverBillable
- A98.5Hemorrhagic fever with renal syndromeBillable
- A98.8Other specified viral hemorrhagic feversBillable
- A99Unspecified viral hemorrhagic feverBillable
- I00Rheumatic fever without heart involvementBillable
- I01Rheumatic fever with heart involvementHeader
- M04.1Periodic fever syndromesBillable
Excludes1
Excludes1 means these codes are not reported together.
From R50. A note on a category applies to every code under it.
Related conditions
Related pages
- R50.9 code detailsNotes, nearby codes, CMS-HCC group
- Category R50Every code under it
- Chapter 18Symptoms, signs and abnormal clinical findings
- ICD-10 codes by conditionA to Z
- Check a list of ICD-10 codes
- Denial code CO-11Diagnosis does not support the procedure
- Denial code CO-146Diagnosis invalid for the date of service
- HCPCS Level II code lookup
Questions
What is the ICD-10 code for Fever of unknown origin?
The CDC title for "Fever of unknown origin" is R50 (Fever of other and unknown origin), a header that is not billable. When nothing more specific is documented, the billable code is R50.9, Fever, unspecified.
Is R50.9 billable?
Yes. R50.9 is a billable code in the FY2027 ICD-10-CM file. Use a more specific code when the record documents one.
What documentation notes apply to R50.9?
The CDC tabular list gives 7 Excludes1 notes (not coded together) for R50.9 and the categories above it. They are listed on this page.
What chapter is R50.9 in?
Chapter 18. Symptoms, signs and abnormal clinical findings.
When do ICD-10-CM codes change?
Every October 1, with the new fiscal year file. Some years add April 1 updates. This page uses the FY2027 file, effective October 1, 2026.