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T78.1 ICD-10-CM Code: Other adverse food reactions, not elsewhere classified

Compare with another code for T78.1Check this code on a claim

Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
3 Excludes1 · 7 Excludes2 · 1 use-additional instruction · 6 code-also instructions

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

7th character:required: report a code with a 7th character· The appropriate 7th character is to be added to each code from category T78See the 7th character note

Use additional codeReport with this code when documented
  • Use additional code to identify the type of reaction, if applicable
Excludes1Not reported with this code unless documented as unrelated
  • anaphylactic reaction or shock due to adverse food reaction (T78.0-)
  • anaphylactic reaction due to food (T78.0-)
  • bacterial food borne intoxications (A05.-)
Code alsofrom T66-T78May be needed with this code
  • Code also, if applicable, place of occurrence, such as:
  • highway rest stop (Y92.523)
  • school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
  • service areas as the place of occurrence of the external cause (Y92.52-)

+2 more in Instructions

Excludes2Not included here; may be reported together
  • allergic and dietetic gastroenteritis and colitis (K52.29)
  • allergic rhinitis due to food (J30.5)
  • dermatitis due to food in contact with skin (L23.6, L24.6, L25.4)
  • dermatitis due to ingested food (L27.2)

+3 more in Instructions

Where it sits Source: CMS/NCHS

Under:Chapter 19: Injury, Poisoning and Certain Other Consequences of External CausesT07-T88 Injury, poisoning and certain other consequences of external causesT66-T78 Other and unspecified effects of external causesT78 Adverse effects, not elsewhere classified

Codes under T78.1 (3)

  • T78.11Other adverse food reactions due to milk and dairy productsNot billable
  • T78.12Other adverse food reaction due to eggsNot billable
  • T78.19Other adverse food reactions, not elsewhere classifiedNot billable

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for T78.1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on T78.1 itself; “inherited from” names the category or block whose note applies here.

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code Also

Additional codes that may be required to fully describe the encounter.

  • Code also, if applicable, place of occurrence, such as:
  • highway rest stop (Y92.523)
  • school (private) (public) (state) as the place of occurrence of the external cause (Y92.21-)
  • service areas as the place of occurrence of the external cause (Y92.52-)
  • single-family non-institutional (private) house as the place of occurrence of the external cause (Y92.01-)
  • transport vehicle as the place of occurrence of the external cause (Y92.81-)

Source: inherited from T66-T78

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code to identify the type of reaction, if applicable

7th Character Guide

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

  • A — initial encounter
  • 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

T78.110A, T78.110D, T78.110S, T78.111A, T78.111D, T78.111S, T78.119A, T78.119D

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 T78.1

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

Before you code T78.1

  1. T78.1 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewT78.11, T78.12

    See the relationships section · Guide: How to choose an ICD-10-CM code →

  2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. T78.1 is not valid without one. “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. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with the code beneath T78.1. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support one of the more specific codes beneath T78.1?
    Yes → Select that code and continue the checks below on its own page.
    No → T78.1 cannot be reported as written. Where the codes beneath it include an unspecified code, that code applies when the record goes no further; otherwise query for the missing detail.

    ReviewT78.11, T78.12

  2. Does the documentation support a condition named in T78.1’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewT78.0, A05

  3. 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.

Report the code beneath T78.1 that the documentation supports, not T78.1 itself. Then work the Use Additional Code note and review the Code Also note, and confirm that code is valid for the date of service on its own page.

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 conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
Any detail beyond this code’s title
What the record states that a more specific code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting T78.1(3 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with T78.1: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareT78.0, A05

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

  • Excludes2 — not part of T78.1(7 notes)

    Coding workflow: The conditions named in this note are not included in T78.1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareK52.29, J30.5, L23.6, L24.6, L25.4, L27.2

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

  • Use Additional Code — after identifying T78.1(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with T78.1 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    See the official tabular notes · Guidelines I.A.13

  • 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

Documentation: Both the condition T78.1 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewT78.0, A05

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with the code beneath T78.1?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

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.

Don’t confuse T78.1 with…

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

The codes most likely to be picked instead of T78.1 — 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.

  • T78.0— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of anaphylactic reaction or shock due to adverse food reaction moves the case to T78.0; the two are not reported together unless documented as unrelated.

    Full comparison: T78.1 vs T78.0 →

  • A05— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of bacterial food borne intoxications moves the case to A05; the two are not reported together unless documented as unrelated.

    Full comparison: T78.1 vs A05 →

  • T78.110A— 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 initial encounter moves the case to T78.110A.

    Full comparison: T78.1 vs T78.110A →

  • T78.110D— 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 T78.110D.

    Full comparison: T78.1 vs T78.110D →

  • K52.29— 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 allergic and dietetic gastroenteritis and colitis adds K52.29; it is not part of this code and both may be reported when both are documented.

    Full comparison: T78.1 vs K52.29 →

  • J30.5— 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 allergic rhinitis due to food adds J30.5; it is not part of this code and both may be reported when both are documented.

    Full comparison: T78.1 vs J30.5 →

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.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Other adverse food reactions, not elsewhere classified is a non-billable ICD-10-CM category code (T78.1). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

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. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  3. 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
  4. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  5. 7 Excludes2 entries — 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

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-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name T78.1 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 1 Excludes1 note: T75 — Other and unspecified effects of other external causes (via T78.-).

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.

Contextual Map

Every relationship of T78.1 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 T78.1 with these 12 related codes in Claim Check

Hierarchy

Excludes1

Excludes2

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Nearest codes (40)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can T78.1 be billed directly?

No. T78.1 (Other adverse food reactions, not elsewhere classified) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Does T78.1 require a 7th character?

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

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) 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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "T78.1 — Other adverse food reactions, not elsewhere classified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/t78.1-other-adverse-food-reactions-not-elsewhere-classified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Other adverse food reactions, not elsewhere classified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to T78.1 in its code family, with their registry titles.

View all codes in the T78 family