ICD-10-CM 2027 diagnosis code
T42.6Poisoning by, adverse effect of and underdosing of other antiepileptic and sedative-hypnotic drugs
T42.6 is a header code, so it can't be reported by itself. Choose one of the 1 more specific codes beneath it and add the required 7th character.Short description: Antiepileptic and sedative-hypnotic drugs
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About T42.6
T42.6 is the ICD-10-CM diagnosis code for poisoning by, adverse effect of and underdosing of other antiepileptic and sedative-hypnotic drugs. It belongs to category T42 (poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs), block T36-T50 (poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 1 subcodes must be used instead.
Within T42, choose T42.6 (other antiepileptic and sedative-hypnotic drugs) only when documentation doesn't support a more specific option: hydantoin derivatives (T42.0), iminostilbenes (T42.1), succinimides and oxazolidinediones (T42.2), barbiturates (T42.3), benzodiazepines (T42.4), mixed antiepileptics (T42.5), unspecified antiepileptic and sedative-hypnotic drugs (T42.7) and antiparkinsonism drugs and other central muscle-tone depressants (T42.8).
Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.
Don't report T42.6 together with the conditions in its Excludes1 note: poisoning by, adverse effect of and underdosing of carbamazepine (T42.1-).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
7th character
The appropriate 7th character is to be added to each code from category T42
- T42.6XPoisoning by, adverse effect of and underdosing of other antiepileptic and sedative-hypnotic drugs
- T42.6X1Poisoning by other antiepileptic and sedative-hypnotic drugs, accidental (unintentional)
- T42.6X2Poisoning by other antiepileptic and sedative-hypnotic drugs, intentional self-harm
- T42.6X3Poisoning by other antiepileptic and sedative-hypnotic drugs, assault
- T42.6X4Poisoning by other antiepileptic and sedative-hypnotic drugs, undetermined
- T42.6X5Adverse effect of other antiepileptic and sedative-hypnotic drugs
- T42.6X6Underdosing of other antiepileptic and sedative-hypnotic drugs
- Ainitial encounter
- Dsubsequent encounter
- Ssequela
Coding notes
- Poisoning by, adverse effect of and underdosing of methaqualone
- Poisoning by, adverse effect of and underdosing of valproic acid
- poisoning by, adverse effect of and underdosing of carbamazepine (T42.1-)
Notes that apply from higher levels
Instructions written at a parent level also apply to T42.6.
Broader instructions also apply from T36-T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances and Chapter 19: Injury, poisoning and certain other consequences of external causes.
Codes whose notes reference T42.6
- T43Excludes2
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about T42.6
Is T42.6 billable?
- No. T42.6 is a header code. Report one of its more specific subcodes instead.