ICD-10/T40.1X1A

T40.1X1A ICD 2026 Code: Poisoning by heroin, accidental (unintentional), initial encounter

T40.1X1A is the authoritative medical code for Poisoning by heroin, accidental (unintentional), initial encounter. This classification is used in medical billing and clinical recording to specify the clinical criteria for poisoning by heroin, accidental (unintentional), initial encounter (ICD-10-CM T40.1X1A), ensuring healthcare documentation aligns with 2026 federal coding standards.

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Official Registry Overview & Definition

Poisoning by heroin, accidental (unintentional), initial encounter is a billable ICD-10-CM diagnosis code T40.1X1A. 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. Inclusion terms: Poisoning by heroin NOS. Excludes1 (not coded here): toxic reaction to local anesthesia in pregnancy O29.3-. Excludes2 (not included here): drug dependence and related mental and behavioral disorders due to psychoactive substance use F10.-F19.-; 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. 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. 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-). 7th character: The appropriate 7th character is to be added to each code from category T40.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for T40.1X1A in the official ICD-10-CM tabular list.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • 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

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Poisoning by heroin NOS

Excludes1 — Not Coded Here

Conditions that can never be reported with this code; the two are mutually exclusive.

  • toxic reaction to local anesthesia in pregnancy O29.3-

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

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

Code First

Underlying conditions that must be sequenced before this code.

  • , 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

Supplementary codes the tabular list directs you to add.

  • 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-)

Frequently Asked Questions (FAQ) & Clinical Guidance

Does T40.1X1A require a 7th character?

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

What can't be coded together with T40.1X1A?

Per Excludes1 instructions, T40.1X1A must not be reported with: toxic reaction to local anesthesia in pregnancy (O29.3-).

Can T40.1X1A be reported alongside related conditions?

Per Excludes2 instructions, T40.1X1A and the following may both be reported when both are present: drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.-F19.-); abuse and dependence of psychoactive substances (F10-F19); abuse of non-dependence-producing substances (F55.-); immunodeficiency due to drugs (D84.821).

Does T40.1X1A need to be sequenced after another code?

Yes. 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).

Is an additional code needed with T40.1X1A?

Use additional code(s) to specify: 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-).

Codes in This Family (40)

Official ICD-10-CM classifications in the same code family as T40.1X1A, with their registry titles.

  • T40 — Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]
  • T40.0 — Poisoning by, adverse effect of and underdosing of opium
  • T40.0X — Poisoning by, adverse effect of and underdosing of opium
  • T40.0X1 — Poisoning by opium, accidental (unintentional)
  • T40.0X1A — Poisoning by opium, accidental (unintentional), initial encounter
  • T40.0X1D — Poisoning by opium, accidental (unintentional), subsequent encounter
  • T40.0X1S — Poisoning by opium, accidental (unintentional), sequela
  • T40.0X2 — Poisoning by opium, intentional self-harm
  • T40.0X2A — Poisoning by opium, intentional self-harm, initial encounter
  • T40.0X2D — Poisoning by opium, intentional self-harm, subsequent encounter
  • T40.0X2S — Poisoning by opium, intentional self-harm, sequela
  • T40.0X3 — Poisoning by opium, assault
  • T40.0X3A — Poisoning by opium, assault, initial encounter
  • T40.0X3D — Poisoning by opium, assault, subsequent encounter
  • T40.0X3S — Poisoning by opium, assault, sequela
  • T40.0X4 — Poisoning by opium, undetermined
  • T40.0X4A — Poisoning by opium, undetermined, initial encounter
  • T40.0X4D — Poisoning by opium, undetermined, subsequent encounter
  • T40.0X4S — Poisoning by opium, undetermined, sequela
  • T40.0X5 — Adverse effect of opium
  • T40.0X5A — Adverse effect of opium, initial encounter
  • T40.0X5D — Adverse effect of opium, subsequent encounter
  • T40.0X5S — Adverse effect of opium, sequela
  • T40.0X6 — Underdosing of opium
  • T40.0X6A — Underdosing of opium, initial encounter
  • T40.0X6D — Underdosing of opium, subsequent encounter
  • T40.0X6S — Underdosing of opium, sequela
  • T40.1 — Poisoning by and adverse effect of heroin
  • T40.1X — Poisoning by and adverse effect of heroin
  • T40.1X1 — Poisoning by heroin, accidental (unintentional)
  • T40.1X1D — Poisoning by heroin, accidental (unintentional), subsequent encounter
  • T40.1X1S — Poisoning by heroin, accidental (unintentional), sequela
  • T40.1X2 — Poisoning by heroin, intentional self-harm
  • T40.1X2A — Poisoning by heroin, intentional self-harm, initial encounter
  • T40.1X2D — Poisoning by heroin, intentional self-harm, subsequent encounter
  • T40.1X2S — Poisoning by heroin, intentional self-harm, sequela
  • T40.1X3 — Poisoning by heroin, assault
  • T40.1X3A — Poisoning by heroin, assault, initial encounter
  • T40.1X3D — Poisoning by heroin, assault, subsequent encounter
  • T40.1X3S — Poisoning by heroin, assault, sequela

Associated Substances (4)

Substances from the official ICD-10-CM Table of Drugs and Chemicals that map to this code.

  • Acetomorphine
  • Diacetylmorphine
  • Diamorphine
  • Heroin

Related Codes & Numerical Sequence (Crawl Map)

Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures:

ICD Code T36.1X1A Poisoning by cephalosporins and other beta-lactam antibiotics, accidental (unintentional), initial encounter
ICD Code T37.1X1A Poisoning by antimycobacterial drugs, accidental (unintentional), initial encounter
ICD Code T38.1X1A Poisoning by thyroid hormones and substitutes, accidental (unintentional), initial encounter
ICD Code T39.1X1A Poisoning by 4-Aminophenol derivatives, accidental (unintentional), initial encounter
ICD Code T41.1X1A Poisoning by intravenous anesthetics, accidental (unintentional), initial encounter
ICD Code T42.1X1A Poisoning by iminostilbenes, accidental (unintentional), initial encounter
ICD Code T43.1X1A Poisoning by monoamine-oxidase-inhibitor antidepressants, accidental (unintentional), initial encounter
ICD Code T44.1X1A Poisoning by other parasympathomimetics [cholinergics], accidental (unintentional), initial encounter
ICD Code T45.1X1A Poisoning by antineoplastic and immunosuppressive drugs, accidental (unintentional), initial encounter
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