2026 ICD-10-CM Diagnosis Code T78.080AAnaphylactic reaction due to egg with tolerance to baked egg, initial encounter

ICD-10-CM Codes›S00–T88›T66-T78›T78

ICD-10-CM T78.080A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T78.080A is a billable ICD-10-CM diagnosis code for anaphylactic reaction due to egg with tolerance to baked egg, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 915 through 916.

Code Identity

ICD-10-CM Code
T78.080A
Billable Status
Yes — Valid for Submission
Code Describes
Anaphylactic reaction due to egg with tolerance to baked egg, initial encounter
Short Description
Anaphyl react due to egg with tolerance to baked egg, init
Parent Code
T78.080
Anaphylactic reaction due to egg with tolerance to baked egg

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT66-T78Other and unspecified effects of external causes
CategoryT78Adverse effects, not elsewhere classified
This CodeT78.080AAnaphylactic reaction due to egg with tolerance to baked egg, initial encounter

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Adverse effects, not elsewhere classified (T78). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Code History & ChangesHistory

New Code T78.080A was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement T78.080A replaces the following previously assigned code(s):

  • T78.08XA - Anaphylactic reaction due to eggs, initial encounter
FY 2026AddedAdded to the ICD-10-CM code setEffective October 1, 2025.
FY 2026CurrentRevised in the current code setEffective October 1, 2025 through September 30, 2026.

Questions About T78.080AOverview

Is T78.080A (Anaphylactic reaction due to egg with tolerance to baked egg) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report anaphylactic reaction due to egg with tolerance to baked egg, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T78.080A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for anaphylactic reaction due to egg with tolerance to baked egg, such as an emergency visit or first evaluation.

What MS-DRG does T78.080A group to?

When anaphylactic reaction due to egg with tolerance to baked egg, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 915, 916, with relative weights from 0.6663 to 1.6816 depending on complications. Higher weights mean higher Medicare reimbursement.