T45.8X3 vs T45.8X4

T45.8X3 (Poisoning by other primarily systemic and hematological agents, assault) compared with T45.8X4 (Poisoning by other primarily systemic and hematological agents, undetermined), from the official CMS tabular data. T45.8X3 and T45.8X4 code the same substance (Aminoethylisothiourium) with a different intent.

Relationship

Informational

Drug table relationship

T45.8X3

Poisoning by other primarily systemic and hematological agents, assault

↔

T45.8X4

Poisoning by other primarily systemic and hematological agents, undetermined

Same substance, different circumstance of exposure.

Same substance — undetermined intent (Aminoethylisothiourium)

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. T45.8X3 and T45.8X4 code the same substance (Aminoethylisothiourium) 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

	T45.8X3Poisoning by other primarily systemic and hematological agents, assault	T45.8X4Poisoning by other primarily systemic and hematological agents, undetermined
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 other primarily systemic and hematological agents, assault is a non-billable ICD-10-CM category code (T45.8X3).	Poisoning by other primarily systemic and hematological agents, undetermined is a non-billable ICD-10-CM category code (T45.8X4).
7th character	The appropriate 7th character is to be added to each code from category T45	The appropriate 7th character is to be added to each code from category T45
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