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ICD-10-CM 2027 diagnosis code

T78.41Arthus phenomenon

Not billable — use a more specific codeRequires 7th character

T78.41 is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it and add the required 7th character.

Looking up by condition? See ICD-10 code for Arthus' phenomenon or reaction.

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 T78.41

T78.41 is the ICD-10-CM diagnosis code for Arthus phenomenon. 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 a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within T78.4 (other and unspecified allergy), T78.41 is specifically for Arthus phenomenon. Related codes cover allergy, unspecified (T78.40) and other allergy (T78.49).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

7th character

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

Coding notes

Applicable toConditions and synonyms classified to this code
  • Arthus reaction

Notes that apply from higher levels

Instructions written at a parent level also apply to T78.41.

› From T78.4 Other and unspecified allergy
Excludes1
  • specified types of allergic reaction such as:
  • allergic diarrhea (K52.29)
  • allergic gastroenteritis and colitis (K52.29)
  • dermatitis (L23-L25, L27.-)
  • food protein-induced enterocolitis syndrome (K52.21)
  • food protein-induced enteropathy (K52.22)
  • hay fever (J30.1)
› From T78 Adverse effects, not elsewhere classified
Excludes2
  • complications of surgical and medical care NEC (T80-T88)

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.

Alphabetic index entries

1 entries

Terms in the official ICD-10-CM index that lead to T78.41.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about T78.41

Is T78.41 billable?

No. T78.41 is a header code. Report one of its more specific subcodes instead.