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ICD-10-CM 2027 diagnosis code

T40.491Poisoning by other synthetic narcotics, accidental (unintentional)

Not billable — use a more specific codeRequires 7th character

T40.491 is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it and add the required 7th character.Short description: Poisoning by other synthetic narcotics, accidental

Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS, effective October 1, 2026. Updated September 29, 2026. About our data

About T40.491

T40.491 is the ICD-10-CM diagnosis code for poisoning by other synthetic narcotics, accidental (unintentional). It belongs to category T40 (poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]), 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 3 subcodes must be used instead.

Within T40.49, choose T40.491 (Poisoning by other synthetic narcotics, accidental (unintentional)) only when documentation doesn't support a more specific option: poisoning by other synthetic narcotics, intentional self-harm (T40.492), poisoning by other synthetic narcotics, assault (T40.493), poisoning by other synthetic narcotics, undetermined (T40.494), adverse effect of other synthetic narcotics (T40.495) and underdosing of other synthetic narcotics (T40.496).

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.

It was added in FY2021, effective October 1, 2020.

7th character

The appropriate 7th character is to be added to each code from category T40

Coding notes

Applicable toConditions and synonyms classified to this code
  • Poisoning by other synthetic narcotics NOS

Notes that apply from higher levels

Instructions written at a parent level also apply to T40.491.

› From T40 Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]
Excludes2
  • drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.-F19.-)

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.

Table of Drugs & Neoplasms entries

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2021 (effective 10/1/2020): Added
  • No changes since FY2021.

Common questions about T40.491

Is T40.491 billable?

No. T40.491 is a header code. Report one of its more specific subcodes instead.