2026 ICD-10-CM Diagnosis Code Z91.0121Allergy to eggs with tolerance to baked egg

ICD-10-CM Codes›Z00–Z99›Z77-Z99›Z91

ICD-10-CM Z91.0121
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z91.0121 is a billable ICD-10-CM diagnosis code for allergy to eggs with tolerance to baked egg. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting.

Code Identity

ICD-10-CM Code
Z91.0121
Billable Status
Yes — Valid for Submission
Code Describes
Allergy to eggs with tolerance to baked egg
Short Description
Allergy to eggs with tolerance to baked egg
Same as the full description in the CMS dataset.
Parent Code
Z91.012
Allergy to eggs

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ77-Z99Persons with potential health hazards related to family and personal history and certain conditions influencing health status
CategoryZ91Personal risk factors, not elsewhere classified
This CodeZ91.0121Allergy to eggs with tolerance to baked egg

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z91.0121.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z91.0121 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Type 1 Excludes

  • Allergy to eggs with reactivity to baked egg Z91.0122

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Allergy, allergic(reaction) (to)
      • food (any) (ingested) NEC
        • status (without reaction)
          • eggs
            • with
              • tolerance to baked egg
    • History
      • personal (of)
        • allergy (to)
          • food
            • eggs
              • with
                • tolerance to baked egg

Code History & ChangesHistory

New Code Z91.0121 was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement Z91.0121 replaces the following previously assigned code(s):

  • Z91.012 - Allergy to eggs
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 Z91.0121Overview

Is Z91.0121 (Allergy to eggs) a billable code?

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

Can Z91.0121 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because allergy to eggs with tolerance to baked egg describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z91.0121 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for allergy to eggs with tolerance to baked egg on inpatient claims.