2027 ICD-10-CM Diagnosis Code T40Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]

ICD-10-CM Codes›S00–T88›T36-T50›T40

ICD-10-CM T40
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T40 is a non-billable ICD-10-CM category code for poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens], so it cannot be submitted on claims. Use a more specific code from this category instead, such as T40.0X1A, T40.0X1D, T40.0X1S, and T40.0X2A.

Code Identity

ICD-10-CM Code
T40
Billable Status
No — Non-Billable Category
Code Describes
Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]
Short Description
Narcotics and psychodysleptics
Chapter
T36-T50
Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT36-T50Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances
CategoryT40Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]
This CodeT40Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]

Specific Coding for Narcotics and psychodyslepticsOverview

Non-specific codes like T40 require more characters. Use one of these billable codes instead:

  • T40.0 for Poisoning by, adverse effect of and underdosing of opium

  • T40.0X for Poisoning by, adverse effect of and underdosing of opium

  • T40.1 for Poisoning by and adverse effect of heroin

  • T40.1X for Poisoning by and adverse effect of heroin

  • T40.2 for Poisoning by, adverse effect of and underdosing of other opioids

  • T40.2X for Poisoning by, adverse effect of and underdosing of other opioids

  • T40.3 for Poisoning by, adverse effect of and underdosing of methadone

  • T40.3X for Poisoning by, adverse effect of and underdosing of methadone

  • T40.4 for Poisoning by, adverse effect of and underdosing of other synthetic narcotics

  • T40.41 for Poisoning by, adverse effect of and underdosing of fentanyl or fentanyl analogs

  • T40.42 for Poisoning by, adverse effect of and underdosing of tramadol

  • T40.49 for Poisoning by, adverse effect of and underdosing of other synthetic narcotics

  • T40.5 for Poisoning by, adverse effect of and underdosing of cocaine

  • T40.5X for Poisoning by, adverse effect of and underdosing of cocaine

  • T40.6 for Poisoning by, adverse effect of and underdosing of other and unspecified narcotics

  • T40.60 for Poisoning by, adverse effect of and underdosing of unspecified narcotics

  • T40.69 for Poisoning by, adverse effect of and underdosing of other narcotics

  • T40.7 for Poisoning by, adverse effect of and underdosing of cannabis (derivatives)

  • T40.71 for Poisoning by, adverse effect of and underdosing of cannabis (derivatives)

  • T40.72 for Poisoning by, adverse effect of and underdosing of synthetic cannabinoids

  • T40.8 for Poisoning by and adverse effect of lysergide [LSD]

  • T40.8X for Poisoning by and adverse effect of lysergide [LSD]

  • T40.9 for Poisoning by, adverse effect of and underdosing of other and unspecified psychodysleptics [hallucinogens]

  • T40.90 for Poisoning by, adverse effect of and underdosing of unspecified psychodysleptics [hallucinogens]

  • T40.99 for Poisoning by, adverse effect of and underdosing of other psychodysleptics [hallucinogens]

Coding GuidelinesGuidance

When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.

The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens] (T40). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T40: its own notes plus those printed at block T36-T50 and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • 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

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • toxic reaction to local anesthesia in pregnancy (O29.3-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

On T40 itself
  • drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.-F19.-)
From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • 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)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Code First

The underlying condition named in the note is sequenced before this code.

From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • 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)

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • 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-)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Notes

General instructions on how these codes are used.

From Block T36-T50 Poisoning by, adverse effect of and underdosing of drugs, medicaments and biological substances applies to 3,186 codes
  • 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.
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

  • The appropriate 7th character is to be added to each code from category T40
  • Ainitial encounter
  • Dsubsequent encounter
  • Ssequela

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

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Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About T40Overview

Is T40 a billable code?

No. This is a category header that groups the codes for poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens], and headers cannot be submitted on claims. Claims for poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens] need a more specific code from this category, such as T40.0X1A, T40.0X1D, and T40.0X1S.

Can T40 be reported with a code from O29.3?

Not as a rule. The Excludes1 note at block T36-T50, which applies to T40, lists "toxic reaction to local anesthesia in pregnancy (O29.3-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).