Excludes1 pair
T78.2- vs T80.5-
T78.2 and T80.5 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on T80.5
allergic reaction or shock NOS (T78.2)
T78.2
Anaphylactic shock, unspecified
Not billable
- Chapter 19
- Injury, poisoning and certain other consequences of external causes
- Section
- T66-T78
Use when the record says
- Allergic shock
- Anaphylactic reaction
- Anaphylaxis
Indexed under
- Allergy, allergic › anaphylactic reaction or shock
- Allergy, allergic › shock (anaphylactic)
- Shock › anaphylactic
T80.5
Anaphylactic reaction due to serum
Not billable
- Chapter 19
- Injury, poisoning and certain other consequences of external causes
- Section
- T80-T88
Use when the record says
- Allergic shock due to serum
- Anaphylactic shock due to serum
- Anaphylactoid reaction due to serum
- Anaphylaxis due to serum
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027