2026 ICD-10-CM Diagnosis Code Z91.0110Allergy to milk products, unspecified

ICD-10-CM Codes›Z00–Z99›Z77-Z99›Z91

ICD-10-CM Z91.0110
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z91.0110 is a billable ICD-10-CM diagnosis code for allergy to milk products, unspecified. 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. Coders also document this condition as allergy to casein.

Code Identity

ICD-10-CM Code
Z91.0110
Billable Status
Yes — Valid for Submission
Code Describes
Allergy to milk products, unspecified
Short Description
Allergy to milk products, unspecified
Same as the full description in the CMS dataset.
Parent Code
Z91.011
Allergy to milk products

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 CodeZ91.0110Allergy to milk products, unspecified

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z91.0110.

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

Z91.0110 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Allergy to casein
  • Allergy to cattle protein
  • Allergy to cheese
  • Allergy to cow's milk protein
  • Hemosiderosis
  • Milk-induced pulmonary disease in infant
  • Secondary hemosiderosis
  • Secondary pulmonary hemosiderosis

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)
          • milk products
    • Allergy, allergic(reaction) (to)
      • milk protein
    • History
      • personal (of)
        • allergy (to)
          • food
            • milk products

Clinical InformationClinical

  • Hemosiderosis

    conditions in which there is a generalized increase in the iron stores of body tissues, particularly of liver and the mononuclear phagocyte system, without demonstrable tissue damage. the name refers to the presence of stainable iron in the tissue in the form of hemosiderin.

  • Hemosiderosis, Pulmonary

    iron deposition within the lung. primary pulmonary hemosiderosis is characterized by hemoptysis; iron-deficiency anemia, and diffuse pulmonary hemorrhage as seen as transient pulmonary infiltrates on radiography. even though large amounts of iron are laid down in the lung, with normal or increased total body iron, anemia occurs because of inability of the erythron to use iron sequestered in pulmonary macrophages.

  • Mononuclear Phagocyte System

    mononuclear cells with pronounced phagocytic ability that are distributed extensively in lymphoid and other organs. it includes macrophages and their precursors; phagocytes; kupffer cells; histiocytes; dendritic cells; langerhans cells; and microglia. the term mononuclear phagocyte system has replaced the former reticuloendothelial system, which also included less active phagocytic cells such as fibroblasts and endothelial cells. (from illustrated dictionary of immunology, 2d ed.)

Code History & ChangesHistory

New Code Z91.0110 was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement Z91.0110 replaces the following previously assigned code(s):

  • Z91.011 - Allergy to milk products
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 Z91.0110Overview

Is Z91.0110 (Allergy to milk products) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report allergy to milk products, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z91.0110 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because allergy to milk products, unspecified describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z91.0110 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 milk products, unspecified on inpatient claims.