ICD-10-CM 2027 diagnosis code
T78.05XAAnaphylactic reaction due to tree nuts and seeds, initial encounter
T78.05XA is a valid, billable ICD-10-CM code for anaphylactic reaction due to tree nuts and seeds, initial encounter. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Anaphylactic reaction due to tree nuts and seeds, init
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About T78.05XA
T78.05XA is the ICD-10-CM diagnosis code for anaphylactic reaction due to tree nuts and seeds, initial encounter. It belongs to category T78 (adverse effects, not elsewhere classified), block T66-T78 (other and unspecified effects of external causes) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 915 (Allergic Reactions with MCC, relative weight 1.6558) and DRG 916 (Allergic Reactions without MCC, relative weight 0.6928), in MDC 21 (Injuries, Poisonings and Toxic Effects of Drugs), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 995.64 (anaphylactic reaction due to tree nuts and seeds).
7th character
Ainitial encounter
CC/MCC status for this injury by encounter: CC for A; Neither CC nor MCC for D, S.
Other encounter types for T78.05:
Notes that apply from higher levels
Instructions written at a parent level also apply to T78.05XA.
› From T78.05 Anaphylactic reaction due to tree nuts and seeds
- anaphylactic reaction due to peanuts (T78.01)
Broader instructions also apply from T66-T78 Other and unspecified effects of external causes and Chapter 19: Injury, poisoning and certain other consequences of external causes.
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 21 · Injuries, Poisonings and Toxic Effects of Drugs
ICD-9-CM equivalent
Converter →- 995.64Anaphylactic reaction due to tree nuts and seedsapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about T78.05XA
Is T78.05XA billable?
- Yes. T78.05XA is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
What does the "A" at the end of T78.05XA mean?
- It is the 7th character for initial encounter. Per the official guidelines, use it while the patient is receiving active treatment for the condition.
Can T78.05XA be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict T78.05XA as a principal diagnosis.
Is T78.05XA a CC or MCC?
- T78.05XA is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does T78.05XA group to?
- T78.05XA is used in the MS-DRG v44.0 logic for MS-DRG 915 (Allergic Reactions with MCC) and MS-DRG 916 (Allergic Reactions without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for T78.05XA?
- The CMS General Equivalence Mappings map T78.05XA to ICD-9-CM 995.64.