ICD-10-CM 2027 diagnosis code
T78.129SOther adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, sequela
T78.129S is a valid, billable ICD-10-CM code for other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, sequela. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Other ad food react d/t egg with bkd egg tol/rct, unsp, sqla
Code last changed in FY2026 (effective October 1, 2025). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About T78.129S
T78.129S is the ICD-10-CM diagnosis code for other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, sequela. It belongs to category T78 (adverse effects, not elsewhere classified), block T66-T78 (other and unspecified effects of external causes) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
The 7th character "S" means sequela: use it for complications or conditions that arise as a direct result of the original condition.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 922 (Other Injury, Poisoning and Toxic Effect Diagnoses with MCC, relative weight 1.6238) and DRG 923 (Other Injury, Poisoning and Toxic Effect Diagnoses without MCC, relative weight 0.9973), in MDC 21 (Injuries, Poisonings and Toxic Effects of Drugs), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.
It was added in FY2026, effective October 1, 2025.
7th character
Ssequela
Other encounter types for T78.129:
Notes that apply from higher levels
Instructions written at a parent level also apply to T78.129S.
› From T78.1 Other adverse food reactions, not elsewhere classified
- code to identify the type of reaction, if applicable
Broader instructions also apply from T66-T78 Other and unspecified effects of external causes and Chapter 19: Injury, poisoning and certain other consequences of external causes.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 21 · Injuries, Poisonings and Toxic Effects of Drugs
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2026 (effective 10/1/2025): Added
- No changes since FY2026.
Common questions about T78.129S
Is T78.129S billable?
- Yes. T78.129S is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
What does the "S" at the end of T78.129S mean?
- It is the 7th character for sequela. Per the official guidelines, use it for complications or conditions that arise as a direct result of the original condition.
Can T78.129S be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is T78.129S a CC or MCC?
- No. T78.129S is neither a CC nor an MCC under MS-DRG v44.0.
What DRG does T78.129S group to?
- T78.129S is used in the MS-DRG v44.0 logic for MS-DRG 922 (Other Injury, Poisoning and Toxic Effect Diagnoses with MCC) and MS-DRG 923 (Other Injury, Poisoning and Toxic Effect Diagnoses without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.