T78.079A ICD-10-CM Code: Anaphylactic reaction due to milk and dairy products, unspecified, initial encounter

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T78.079A in the official ICD-10-CM tabular list, quoted as published.

Notes without a marker are published on T78.079A itself; “inherited from” names the category or block whose note applies here.

7th Character Guide

"The appropriate 7th character is to be added to each code from category T78"

• A — initial encounter (this page’s code)
• D — subsequent encounter
• S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

T78.079A, T78.079D, T78.079S

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for T78.079A

MedCoder structured workflow — derived from this code’s own official record

Before you code T78.079A

1. Unspecified does not mean incorrect. When the record gives no greater specificity, T78.079A may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by the presence or absence of the associated condition. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   ReviewT78.070A, T78.071A

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. This page’s code carries “A”. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

   See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

3. T78.079A’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

   Guide: Combination codes →

Choose the right path

1. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — T78.079A is appropriate when the documentation goes no further.

   ReviewT78.070A, T78.071A

2. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
   Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
   No → The code is invalid without its 7th character — query for the missing element.

Consider T78.079A. Then review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Encounter type

Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).

The associated condition or complication

Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes2 — not part of T78.079A(1 note)

  Coding workflow: The conditions named in this note are not included in T78.079A. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

  See the official tabular notes · Guidelines I.A.12.b

• Code Also — related condition(6 notes)

  Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

  ReviewY92.523, Y92.21, Y92.52, Y92.01, Y92.81

  See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (4)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Allergy, allergic (reaction) (to), dairy products, anaphylactic reaction
• Allergy, allergic (reaction) (to), milk protein, anaphylactic reaction
• Shock, anaphylactic, due to food (nonpoisonous), dairy products
• Shock, anaphylactic, due to food (nonpoisonous), milk

Don’t confuse T78.079A with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of T78.079A — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• T78.079D— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a subsequent encounter moves the case to T78.079D.

  Full comparison: T78.079A vs T78.079D →

• T78.079S— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a sequela moves the case to T78.079S.

  Full comparison: T78.079A vs T78.079S →

• T80— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of complications of surgical and medical care NEC adds T80; it is not part of this code and both may be reported when both are documented.

  Full comparison: T78.079A vs T80 →

• T88— Excludes2 relationship (Informational)

  Distinct conditions — both may be reported.

  A distinct condition — both may be reported when both are documented.

  What moves you there: Documentation of complications of surgical and medical care NEC adds T88; it is not part of this code and both may be reported when both are documented.

  Full comparison: T78.079A vs T88 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
2. 6 Code Also notes — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
3. 1 Excludes2 entry — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name T78.079A or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 8 Excludes1 notes across 2 chapters: R57 — Shock, not elsewhere classified (via T78.0.-), T61 — Toxic effect of noxious substances eaten as seafood (via T78.0.-), T62 — Toxic effect of other noxious substances eaten as food (via T78.0.-), T75 — Other and unspecified effects of other external causes (via T78.-), T78.1 — Other adverse food reactions, not elsewhere classified (via T78.0.-), T78.2 — Anaphylactic shock, unspecified (via T78.0.-), T79.4 — Traumatic shock (via T78.0.-), T88.6 — Anaphylactic reaction due to adverse effect of correct drug or medicament properly administered (via T78.0.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: L27 — Dermatitis due to substances taken internally (via T78.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 14 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 915 (MDC 21), DRG 916 (MDC 21).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INJ031 — Allergic reactions (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

T78.00XA — Anaphylactic reaction due to unspecified food, initial encounter, T78.01XA — Anaphylactic reaction due to peanuts, initial encounter, T78.02XA — Anaphylactic reaction due to shellfish (crustaceans), initial encounter, T78.03XA — Anaphylactic reaction due to other fish, initial encounter, T78.04XA — Anaphylactic reaction due to fruits and vegetables, initial encounter, T78.05XA — Anaphylactic reaction due to tree nuts and seeds, initial encounter, T78.06XA — Anaphylactic reaction due to food additives, initial encounter, T78.070A — Anaphylactic reaction due to milk and dairy products with tolerance to baked milk, initial encounter, T78.071A — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk, initial encounter, T78.080A — Anaphylactic reaction due to egg with tolerance to baked egg, initial encounter, T78.081A — Anaphylactic reaction due to egg with reactivity to baked egg, initial encounter, T78.089A — Anaphylactic reaction due to eggs, unspecified, initial encounter, T78.09XA — Anaphylactic reaction due to other food products, initial encounter

Same injury, other encounter phase

Same injury, coded at a different phase of treatment via the 7th character.

T78.079D — Anaphylactic reaction due to milk and dairy products, unspecified, subsequent encounterCompare T78.079A vs T78.079D →, T78.079S — Anaphylactic reaction due to milk and dairy products, unspecified, sequelaCompare T78.079A vs T78.079S →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Allergic reactions).

M36.4 — Arthropathy in hypersensitivity reactions classified elsewhere, T78.00XA — Anaphylactic reaction due to unspecified food, initial encounter, T78.01XA — Anaphylactic reaction due to peanuts, initial encounter, T78.02XA — Anaphylactic reaction due to shellfish (crustaceans), initial encounter, T78.03XA — Anaphylactic reaction due to other fish, initial encounter, T78.04XA — Anaphylactic reaction due to fruits and vegetables, initial encounter, T78.05XA — Anaphylactic reaction due to tree nuts and seeds, initial encounter, T78.06XA — Anaphylactic reaction due to food additives, initial encounter, T78.070A — Anaphylactic reaction due to milk and dairy products with tolerance to baked milk, initial encounter, T78.071A — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk, initial encounter, T78.080A — Anaphylactic reaction due to egg with tolerance to baked egg, initial encounter, T78.081A — Anaphylactic reaction due to egg with reactivity to baked egg, initial encounter, T78.089A — Anaphylactic reaction due to eggs, unspecified, initial encounter, T78.09XA — Anaphylactic reaction due to other food products, initial encounter, T78.110A — Other adverse food reactions due to milk and dairy products with tolerance to baked milk, initial encounter, T78.111A — Other adverse food reaction due to milk and dairy products with reactivity to baked milk, initial encounter, T78.119A — Other adverse food reaction due to milk and dairy products with baked milk tolerance/reactivity, unspecified, initial encounter, T78.120A — Other adverse food reaction due to egg with tolerance to baked egg, initial encounter, T78.121A — Other adverse food reaction due to egg with reactivity to baked egg, initial encounter, T78.129A — Other adverse food reaction due to egg with baked egg tolerance/reactivity, unspecified, initial encounter, +93 more

Contextual Map

Every relationship of T78.079A in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run T78.079A with these 9 related codes in Claim Check

Hierarchy

• S00-T88 — Chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) (S00-T88)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T66-T78 — Other and unspecified effects of external causes[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Excludes1 notes

• R57 — Shock, not elsewhere classified[Excludes1](via T78.0.-): “anaphylactic reaction or shock due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T61 — Toxic effect of noxious substances eaten as seafood[Excludes1](via T78.0.-): “anaphylactic reaction or shock due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T62 — Toxic effect of other noxious substances eaten as food[Excludes1](via T78.0.-): “anaphylactic shock (reaction) due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T75 — Other and unspecified effects of other external causes[Excludes1](via T78.-): “adverse effects NEC (T78.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T78.1 — Other adverse food reactions, not elsewhere classified[Excludes1](via T78.0.-): “anaphylactic reaction or shock due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T78.2 — Anaphylactic shock, unspecified[Excludes1](via T78.0.-): “anaphylactic reaction or shock due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T79.4 — Traumatic shock[Excludes1](via T78.0.-): “anaphylactic shock due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T88.6 — Anaphylactic reaction due to adverse effect of correct drug or medicament properly administered[Excludes1](via T78.0.-): “anaphylactic shock or reaction due to adverse food reaction (T78.0-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

• L27 — Dermatitis due to substances taken internally[Excludes2](via T78.-): “adverse food reaction, except dermatitis (T78.0-T78.1)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• INJ031 — Allergic reactions[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 915 — ALLERGIC REACTIONS WITH MCC[MS-DRG]: “ALLERGIC REACTIONS WITH MCC (MDC 21)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 916 — ALLERGIC REACTIONS WITHOUT MCC[MS-DRG]: “ALLERGIC REACTIONS WITHOUT MCC (MDC 21)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 21 — Injuries, Poisonings and Toxic Effects of Drugs[MDC crossing]: “Injuries, Poisonings and Toxic Effects of Drugs — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 32,029 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Allergy, allergic (reaction) (to), dairy products, anaphylactic reaction[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Allergy, allergic (reaction) (to), milk protein, anaphylactic reaction[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Shock, anaphylactic, due to food (nonpoisonous), dairy products[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Shock, anaphylactic, due to food (nonpoisonous), milk[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (40)

• T78 — Adverse effects, not elsewhere classified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.04XD — Anaphylactic reaction due to fruits and vegetables, subsequent encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.04XS — Anaphylactic reaction due to fruits and vegetables, sequela[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.05 — Anaphylactic reaction due to tree nuts and seeds[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.05XA — Anaphylactic reaction due to tree nuts and seeds, initial encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.05XD — Anaphylactic reaction due to tree nuts and seeds, subsequent encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.05XS — Anaphylactic reaction due to tree nuts and seeds, sequela[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• T78.06 — Anaphylactic reaction due to food additives[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

Change history

• FY2026 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2026

Common coding questions

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T78.079A in its code family, with their registry titles.

• T78.071 — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk
• T78.071A — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk, initial encounter
• T78.071D — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk, subsequent encounter
• T78.071S — Anaphylactic reaction due to milk and dairy products with reactivity to baked milk, sequela
• T78.079 — Anaphylactic reaction due to milk and dairy products, unspecified
• T78.079D — Anaphylactic reaction due to milk and dairy products, unspecified, subsequent encounter
• T78.079S — Anaphylactic reaction due to milk and dairy products, unspecified, sequela
• T78.08 — Anaphylactic reaction due to eggs
• T78.080 — Anaphylactic reaction due to egg with tolerance to baked egg
• T78.080A — Anaphylactic reaction due to egg with tolerance to baked egg, initial encounter

View all codes in the T78 family