2026 ICD-10-CM Diagnosis Code T78.00XSAnaphylactic reaction due to unspecified food, sequela
T78.00XS is a billable ICD-10-CM diagnosis code for anaphylactic reaction due to unspecified food, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. 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 exempt from POA reporting. Coders also document this condition as anaphylaxis caused by ingested food. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T78.00XS 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.
- Anaphylaxis caused by ingested food
- Exercise anaphylaxis
- Food anaphylaxis
- Food-dependent exercise-induced anaphylaxis
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 ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Anaphylaxis
Anaphylaxis is a serious allergic reaction. It can begin very quickly, and symptoms may be life-threatening. The most common causes are reactions to foods (especially peanuts), medications, and stinging insects. Other causes include exercise and exposure to latex. Sometimes no cause can be found.
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Convert T78.00XS to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T78.00XSOverview
Is T78.00XS (Anaphylactic reaction due to unspecified food) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report anaphylactic reaction due to unspecified food, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in T78.00XS mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the anaphylactic reaction due to unspecified food itself has resolved, not the original event.
What MS-DRG does T78.00XS group to?
When anaphylactic reaction due to unspecified food, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
Is T78.00XS 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 anaphylactic reaction due to unspecified food, sequela on inpatient claims.
What is the ICD-9 equivalent of T78.00XS?
Under the General Equivalence Mappings, anaphylactic reaction due to unspecified food, sequela converts to ICD-9-CM 909.9 (late eff exter cause NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
