2026 ICD-10-CM Diagnosis Code T78.19XAOther adverse food reactions, not elsewhere classified, initial encounter

ICD-10-CM Codes›S00–T88›T66-T78›T78

ICD-10-CM T78.19XA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T78.19XA is a billable ICD-10-CM diagnosis code for other adverse food reactions, not elsewhere classified, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. The code is not accepted as a principal diagnosis by the Medicare Code Editor.

Code Identity

ICD-10-CM Code
T78.19XA
Billable Status
Yes — Valid for Submission
Code Describes
Other adverse food reactions, not elsewhere classified, initial encounter
Short Description
Other adverse food reactions, NEC, initial encounter
Parent Code
T78.19
Other adverse food reactions, not elsewhere classified

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT66-T78Other and unspecified effects of external causes
CategoryT78Adverse effects, not elsewhere classified
This CodeT78.19XAOther adverse food reactions, not elsewhere classified, initial encounter

Code EditsBilling

Medicare Code Editor checks that affect claim validity for T78.19XA.

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.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adverse drug interaction
  • Adverse medication interaction with food
  • Adverse reaction caused by monosodium glutamate
  • Adverse reaction to chewing gum additive
  • Adverse reaction to fig
  • Adverse reaction to food
  • Adverse reaction to food additive
  • Allergic angioedema
  • Allergic angioedema due to ingested food
  • Allergic bronchospasm caused by dietary substance
  • Allergic reaction caused by fish
  • Allergic reaction caused by food additive
  • Allergic reaction caused by fruit
  • Allergic reaction caused by mollusk
  • Allergic reaction caused by peanut
  • Allergic reaction caused by seafood
  • Allergic reaction caused by seed
  • Allergic reaction caused by shellfish
  • Allergic reaction caused by tree nut
  • Allergic reaction to food
  • Allergic urticaria caused by ingested food
  • Allergy to food
  • Bronchospasm
  • Enteral and supplement feeds adverse reaction
  • Food-induced angioedema-urticaria
  • Headache caused by monosodium glutamate
  • Hypersensitivity reaction caused by food
  • Intolerance to monosodium glutamate
  • Medication interaction with food
  • Non-allergic hypersensitivity reaction caused by sulfite

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Adverse effects, not elsewhere classified (T78). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical InformationClinical

  • Bronchospasm

    sudden contraction of the smooth muscles of the bronchial wall.

  • Bronchospasm, CTCAE|Bronchospasm|Bronchospasm

    a disorder characterized by a sudden contraction of the smooth muscles of the bronchial wall or narrowing of the airway. may be manifested as wheezing.

  • Exercise-Induced Bronchospasm|Exercise induced bronchospasm

    sudden contraction of the smooth muscles of the bronchial wall that occurs during or following exercise.

  • Grade 1 Bronchospasm, CTCAE|Grade 1 Bronchospasm

    mild symptoms; intervention not indicated

  • Grade 2 Bronchospasm, CTCAE|Grade 2 Bronchospasm

    symptomatic; medical intervention indicated; limiting instrumental adl or mild/moderate impact on age-appropriate normal daily activity (pediatric)

  • Grade 3 Bronchospasm, CTCAE|Grade 3 Bronchospasm

    supplemental oxygen indicated; limiting self-care adl or severe impact on age-appropriate normal daily activity (pediatric)

  • Grade 4 Bronchospasm, CTCAE|Grade 4 Bronchospasm

    life-threatening respiratory or hemodynamic compromise; intubation or urgent intervention indicated

  • Grade 5 Bronchospasm, CTCAE|Grade 5 Bronchospasm

    death

Code History & ChangesHistory

New Code T78.19XA was added to the ICD-10-CM code set for FY 2026, effective October 1, 2025.

Replacement T78.19XA replaces the following previously assigned code(s):

  • T78.1XXA - Oth adverse food reactions, not elsewhere classified, init
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 T78.19XAOverview

Is T78.19XA (Other adverse food reactions, not elsewhere classified) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other adverse food reactions, not elsewhere classified, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T78.19XA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for other adverse food reactions, not elsewhere classified, such as an emergency visit or first evaluation.

What MS-DRG does T78.19XA group to?

On inpatient claims, other adverse food reactions, not elsewhere classified, initial encounter maps to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.

Can T78.19XA be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because other adverse food reactions, not elsewhere classified, initial encounter describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.