T40.491 vs T40.494

T40.491 (Poisoning by other synthetic narcotics, accidental (unintentional)) compared with T40.494 (Poisoning by other synthetic narcotics, undetermined), from the official CMS tabular data. T40.491 and T40.494 code the same substance (Alphaprodine) with a different intent.

Relationship

Informational

Drug table relationship

T40.491

Poisoning by other synthetic narcotics, accidental (unintentional)

↔

T40.494

Poisoning by other synthetic narcotics, undetermined

Same substance, different circumstance of exposure.

Same substance — undetermined intent (Alphaprodine)

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. T40.491 and T40.494 code the same substance (Alphaprodine) 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

	T40.491Poisoning by other synthetic narcotics, accidental (unintentional)	T40.494Poisoning by other synthetic narcotics, 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 synthetic narcotics, accidental (unintentional) is a non-billable ICD-10-CM category code (T40.491).	Poisoning by other synthetic narcotics, undetermined is a non-billable ICD-10-CM category code (T40.494).
7th character	The appropriate 7th character is to be added to each code from category T40	The appropriate 7th character is to be added to each code from category T40
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