T42.75 vs T42.76

T42.75 (Adverse effect of unspecified antiepileptic and sedative-hypnotic drugs) compared with T42.76 (Underdosing of unspecified antiepileptic and sedative-hypnotic drugs), from the official CMS tabular data. T42.75 and T42.76 code the same substance (Anticonvulsant) with a different intent.

Relationship

Informational

Drug table relationship

T42.75

Adverse effect of unspecified antiepileptic and sedative-hypnotic drugs

↔

T42.76

Underdosing of unspecified antiepileptic and sedative-hypnotic drugs

Same substance, different circumstance of exposure.

Same substance — underdosing (Anticonvulsant)

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. T42.75 and T42.76 code the same substance (Anticonvulsant) 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

	T42.75Adverse effect of unspecified antiepileptic and sedative-hypnotic drugs	T42.76Underdosing of unspecified antiepileptic and sedative-hypnotic drugs
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	Adverse effect of unspecified antiepileptic and sedative-hypnotic drugs is a non-billable ICD-10-CM category code (T42.75).	Underdosing of unspecified antiepileptic and sedative-hypnotic drugs is a non-billable ICD-10-CM category code (T42.76).
7th character	The appropriate 7th character is to be added to each code from category T42	The appropriate 7th character is to be added to each code from category T42
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