ICD-10 Code for Pyrexia
Also indexed as (of unknown origin)
The ICD-10-CM code for pyrexia is R50.9 — Fever, unspecified. This is the code the Alphabetic Index gives for pyrexia with no further qualifier, valid for FY2027 (October 1, 2026 – September 30, 2027).
R50.9 is billable but unspecified. If the documentation names a type, site or cause, one of the more specific codes below is likely expected.
Which pyrexia code should you use?
The Alphabetic Index lists 6 codes under Pyrexia. Which one applies depends on the qualifier documented in the record — the type, site, cause, or associated condition. Find the qualifier below, then verify the code in the Tabular List before using it.
By type
| atmospheric | T67.01 | Heatstroke and sunstroke | not billable |
| during labor NEC | O75.2 | Pyrexia during labor, not elsewhere classified | |
| heat | T67.01 | Heatstroke and sunstroke | not billable |
| newborn | P81.9 | Disturbance of temperature regulation of newborn, unspecified | |
| persistent | R50.9 | Fever, unspecified | |
| puerperal | O86.4 | Pyrexia of unknown origin following delivery |
Pyrexia newborn
| environmentally-induced | P81.0 | Environmental hyperthermia of newborn |
Index terms and codes are reproduced from the official ICD-10-CM FY2027 release. The Alphabetic Index is a finding aid — a code must always be verified in the Tabular List before it is reported. Data sources