Is T37.3X5A a billable ICD-10-CM code?

Yes. T37.3X5A is a billable, specific ICD-10-CM code and is valid for submission on a claim.

Where does T37.3X5A sit in the tabular list?

Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50).

What cannot be coded together with T37.3X5A?

T37.3X5A carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T37.3X5A (T37) and apply to it just the same.

T37.3X5A

T37.3X5A — Adverse effect of other antiprotozoal drugs, initial encounter

Billable / specific codeICD-10-CM

T37.3X5A is a billable, specific ICD-10-CM code for adverse effect of other antiprotozoal drugs, 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 T37

A: initial encounter
D: subsequent encounter
S: sequela

Excludes1 inherited from the categories above T37.3X5A

These are not written on T37.3X5A, but they bind it: a note on a category applies to every code beneath it. Billing T37.3X5A with anything listed here is a denial.

Written on T37 — Poisoning by, adverse effect of and underdosing of other systemic anti-infectives and antiparasitics

anti-infectives topically used for ear, nose and throat (T49.6-)
anti-infectives topically used for eye (T49.5-)
locally applied anti-infectives NEC (T49.0-)

Risk adjustment

T37.3X5A 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

T37.3X5A is named in 18 Medicare coverage policies — 18 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.

A56558Billing and Coding: Allergy Testing
A56844Billing and Coding: RAST Type Tests
A57043Billing and Coding: RAST Type Tests
A57189Billing and Coding: Serum Magnesium

Code history

T37.3X5A has not changed since FY2024 — no addition, revision or deletion across the FY2024–FY2027 ICD-10-CM releases.

Related codes at this level

Codes that share T37.3X5. If T37.3X5A is not quite right, the correct code is usually one of these.

Questions about T37.3X5A

Is T37.3X5A a billable ICD-10-CM code?: Yes. T37.3X5A is a billable, specific ICD-10-CM code and is valid for submission on a claim.
Where does T37.3X5A sit in the tabular list?: Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50).
What cannot be coded together with T37.3X5A?: T37.3X5A carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above T37.3X5A (T37) and apply to it just the same.