DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

R50 Fever of other and unknown origin

  • Header · not billable

R50 is not billable. The category heads 6 billable codes in FY2027, grouped under 3 subdivisions.

Index → code

  • Hyperpyrexia → R50.9
  • Pyrexia (of unknown origin) → R50.9
  • FUO (fever of unknown origin) → R50.9

Where it sits

  1. Chapter 18 Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99)
  2. R50-R69 General symptoms and signs (R50-R69)
  3. R50 Fever of other and unknown origin
Billable codes
6
Subdivisions
3
CC / MCC codes
0 / 0
HCC V28 codes
0
New FY2027
0
Index entries
31

Codes in R50

  1. R50.2
    Drug induced fever
    Billable
    Excludes1 1, Use additional code 1

    Excludes1

    • postvaccination (postimmunization) fever (R50.83) R50.83

    Use additional code

    • code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5) T36 T50
  2. R50.8
    Other specified fever
    Header
  3. R50.81
    Fever presenting with conditions classified elsewhere
    Billable
    Code first 4

    Code first

    • underlying condition when associated fever is present, such as with:
    • leukemia (C91-C95) C91 C95
    • neutropenia (D70.-) D70
    • sickle-cell disease (D57.-) D57
  4. R50.82
    Postprocedural fever
    Billable
    Excludes1 3

    Excludes1

    • postprocedural infection (T81.4-) T81.4
    • posttransfusion fever (R50.84) R50.84
    • postvaccination (postimmunization) fever (R50.83) R50.83
  5. R50.83
    Postvaccination fever
    Billable
    Inclusion terms 1

    Inclusion terms

    • Postimmunization fever
  6. R50.84
    Febrile nonhemolytic transfusion reaction
    Billable
    Inclusion terms 2

    Inclusion terms

    • FNHTR
    • Posttransfusion fever
  7. R50.9
    Fever, unspecified
    Billable
    Inclusion terms 7

    Inclusion terms

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

Sources of each column.

Instructions

At R50

Excludes1

  • chills without fever (R68.83) R68.83
  • febrile convulsions (R56.0-) R56.0
  • fever of unknown origin during labor (O75.2) O75.2
  • fever of unknown origin in newborn (P81.9) P81.9
  • hypothermia due to illness (R68.0) R68.0
  • malignant hyperthermia due to anesthesia (T88.3) T88.3
  • puerperal pyrexia NOS (O86.4) O86.4

Notes that also apply

Chapter 18 instructions (Notes 9, Excludes2 4): printed on the chapter 18 page.

Index entries

  • FNHTR (febrile nonhemolytic transfusion reaction) → R50.84
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) → R50.9
  • FUO (fever of unknown origin) → R50.9
  • Hyperpyrexia → R50.9
  • PUO (pyrexia of unknown origin) → R50.9
  • Pyrexia (of unknown origin) → R50.9
  • Druginduced fever → R50.2
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)drug induced → R50.2
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)iodide → R50.2
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)steroid → R50.2
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)presenting with conditions classified elsewhere → R50.81
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)postoperative → R50.82
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)postimmunization → R50.83
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)postvaccination → R50.83
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)posttransfusion → R50.84
  • Reactionfebrile nonhemolytic transfusion (FNHTR) → R50.84
  • Chill(s)with fever → R50.9
  • Elevated, elevationbody temperature (of unknown origin) → R50.9
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)ephemeral (of unknown origin) → R50.9
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)persistent (of unknown origin) → R50.9
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)unknown origin → R50.9
  • Hightemperature (of unknown origin) → R50.9
  • Hyperpyrexiaunknown origin → R50.9
  • Inanitionfever → R50.9
  • Pyrexia (of unknown origin)persistent → R50.9
  • Rigorswith fever → R50.9
  • Temperaturebody, high (of unknown origin) → R50.9
  • Steroideffects (adverse) (adrenocortical) (iatrogenic)fever → R50.2
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)due toconditions classified elsewhere → R50.81
  • Complication(s) (from) (of)transfusion (blood) (lymphocytes) (plasma)febrile nonhemolytic transfusion reaction → R50.84
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor)intermittent (bilious)of unknown origin → R50.9

NCHS Alphabetic Index. Index first, then the Tabular List.

Hierarchy