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E73 vs Z91.011

E73 (Lactose intolerance) compared with Z91.011 (Allergy to milk products), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.

Can these codes be reported together?

No — do not report together. Z91.011 carries an Excludes1 note covering E73: “lactose intolerance (E73.-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Side by side

E73Lactose intoleranceZ91.011Allergy to milk products
Billing statusNon-billable header

Report instead: E73.0, E73.1, E73.8, E73.9

Non-billable header

Report instead: Z91.0110, Z91.0111, Z91.0112

ClassificationE00-E89 — Endocrine, Nutritional and Metabolic Diseases (E00-E89)Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99)
DefinitionLactose intolerance is a non-billable ICD-10-CM category code (E73).Allergy to milk products is a non-billable ICD-10-CM category code (Z91.011).
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources