T78.4 — Other and unspecified allergy
T78.4 is a non-billable header ICD-10-CM code for other and unspecified allergy. It cannot be billed on its own: choose one of the more specific child codes below. This code also requires a 7th character before it is complete.
This code requires a 7th character
The appropriate 7th character is to be added to each code from category T78
- A
- initial encounter
- D
- subsequent encounter
- S
- sequela
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
Other codes that can never be billed with T78.4
These codes carry an Excludes1 note pointing at T78.4. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading T78.4 alone.
Risk adjustment
T78.4 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.
Code to one of these instead T78.4
3 child codes. Green means billable.
Related codes at this level
Codes that share T78. If T78.4 is not quite right, the correct code is usually one of these.
Questions about T78.4
- Is T78.4 a billable ICD-10-CM code?
- No. T78.4 is a non-billable header code. Code to a higher level of specificity using one of its child codes.
- Where does T78.4 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).
- What cannot be coded together with T78.4?
- T78.4 carries an Excludes1 note, which means the conditions it lists can never be coded together with it on the same encounter.