T37.2X4 vs T37.2X6

T37.2X4 (Poisoning by antimalarials and drugs acting on other blood protozoa, undetermined) compared with T37.2X6 (Underdosing of antimalarials and drugs acting on other blood protozoa), from the official CMS tabular data. T37.2X4 and T37.2X6 code the same substance (8-Aminoquinoline) with a different intent.

Relationship

Informational

Drug table relationship

T37.2X4

Poisoning by antimalarials and drugs acting on other blood protozoa, undetermined

↔

T37.2X6

Underdosing of antimalarials and drugs acting on other blood protozoa

Same substance, different circumstance of exposure.

Same substance — underdosing (8-Aminoquinoline)

Accidental poisoning, intentional self-harm, assault, undetermined intent, adverse effect and underdosing are mutually exclusive columns — exactly one applies to a given encounter.

Source: CMS Table of Drugs and Chemicals

Can these codes be reported together?

Same substance, different intent. T37.2X4 and T37.2X6 code the same substance (8-Aminoquinoline) with a different circumstance of exposure.

From the CMS Table of Drugs and Chemicals: accidental poisoning, intentional self-harm, assault, undetermined intent, adverse effect and underdosing are mutually exclusive columns — only one of them applies to a given encounter.

Side by side

	T37.2X4Poisoning by antimalarials and drugs acting on other blood protozoa, undetermined	T37.2X6Underdosing of antimalarials and drugs acting on other blood protozoa
Billing status	Non-billable header	Non-billable header
Classification	S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)	S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
Definition	Poisoning by antimalarials and drugs acting on other blood protozoa, undetermined is a non-billable ICD-10-CM category code (T37.2X4).	Underdosing of antimalarials and drugs acting on other blood protozoa is a non-billable ICD-10-CM category code (T37.2X6).
7th character	The appropriate 7th character is to be added to each code from category T37	The appropriate 7th character is to be added to each code from category T37
Includes	adverse effect of correct substance properly administered poisoning by overdose of substance poisoning by wrong substance given or taken in error underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed	adverse effect of correct substance properly administered poisoning by overdose of substance poisoning by wrong substance given or taken in error underdosing by (inadvertently) (deliberately) taking less substance than prescribed or instructed
Use additional code	code(s) to specify: manifestations of poisoning underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9)	code(s) to specify: manifestations of poisoning underdosing or failure in dosage during medical and surgical care (Y63.6, Y63.8-Y63.9)
Code first	, for adverse effects, the nature of the adverse effect, such as: adverse effect NOS (T88.7)	, for adverse effects, the nature of the adverse effect, such as: adverse effect NOS (T88.7)

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources