Underdosing of mixed antiepileptics, initial encounter

ValidICD-10-CM diagnosis code.

Valid for claims with a date of service in the current code year.

Valid FY2016 onwards.

What has happened to this code

Every change the publisher made, from 2007 to now. Entries marked draft are from the pre-implementation releases: ICD-10 took effect on 1 October 2015, so nothing before FY2016 was ever valid on a claim.

FY2007 Added to the draft code set draft Underdosing of mixed antiepileptics, initial encounter

Official coding rules

Published by CDC for FY2027. A rule attached to a category binds every code beneath it, so the rules inherited from this code's ancestors are shown with the code they come from.

Inherited from T42 Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs

Seventh character required

The appropriate 7th character is to be added to each code from category T42

Excludes2 - not included here

drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.--F19.-)

Inherited from the T36-T50 section Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50)

Excludes1 - never coded here

toxic reaction to local anesthesia in pregnancy (O29.3-)

Excludes2 - not included here

abuse and dependence of psychoactive substances (F10-F19)
abuse of non-dependence-producing substances (F55.-)
immunodeficiency due to drugs (D84.821)
drug reaction and poisoning affecting newborn (P00-P96)
pathological drug intoxication (inebriation) (F10-F19)

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)
underdosing of medication regimen (Z91.12-, Z91.13-)

Code first

, for adverse effects, the nature of the adverse effect, such as:
adverse effect NOS (T88.7)
aspirin gastritis (K29.-)
blood disorders (D56-D76)
contact dermatitis (L23-L25)
dermatitis due to substances taken internally (L27.-)
nephropathy (N14.0-N14.2)

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

Note

The drug giving rise to the adverse effect should be identified by use of codes from categories T36-T50 with fifth or sixth character 5.

How CDC's index refers to this code

Wording from the official alphabetic index. Much of it appears nowhere in the code description, which is why a search for the everyday phrase so often finds nothing.

Antiepilepsy agent > mixed
Antiepilepsy agent > combination

Codes in the same group

Code	Description	Status
T42.5X6D	Underdosing of mixed antiepileptics, subsequent encounter	Valid
T42.5X6S	Underdosing of mixed antiepileptics, sequela	Valid