T78.00XA — Anaphylactic reaction due to unspecified food, initial encounter
T78.00XA is a billable, specific ICD-10-CM code for anaphylactic reaction due to unspecified food, initial encounter. It is valid for submission on a claim.
7th character "A" — initial encounter
The appropriate 7th character is to be added to each code from category T78
- A
- initial encounter
- D
- subsequent encounter
- S
- sequela
Excludes2 inherited from the categories above T78.00XA
Also inherited, and the opposite of Excludes1: these conditions are not part of T78.00XA, but a patient can have both, so you may code both.
Other codes that can never be billed with T78.00XA
These codes carry an Excludes1 note pointing at T78.00XA. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading T78.00XA alone.
- T75Other and unspecified effects of other external causes
Risk adjustment
T78.00XA does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
T78.00XA is named in 9 Medicare coverage policies — 9 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A56612Billing and Coding: CT of the Head
- A56844Billing and Coding: RAST Type Tests
- A57043Billing and Coding: RAST Type Tests
- A57326Billing and Coding: Electrocardiograms
Code history
T78.00XA has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share T78.00. If T78.00XA is not quite right, the correct code is usually one of these.
Questions about T78.00XA
- Is T78.00XA a billable ICD-10-CM code?
- Yes. T78.00XA is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does T78.00XA sit in the tabular list?
- Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Other and unspecified effects of external causes (T66-T78).