Alphabetic Index FY2027

T40.491

Poisoning by other synthetic narcotics, accidental (unintentional)

FY2027Chapter 19: Injury, poisoning and certain other consequences of external causes/T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances

Non-billable headerNot valid on its own. Use one of the more specific codes under it.

T40.491 is a non-billable ICD-10-CM code header for poisoning by other synthetic narcotics, accidental (unintentional). Report a more specific code from it instead. It is part of the FY2027 code set, effective October 1, 2026. A 7th character is required to complete the code. Its coding notes include a Code first instruction, a Use additional code instruction, 1 Excludes1 entry and 8 Excludes2 entries.

7th character

Category T40 requires a 7th character.

Assembled code T40.491A Open code

Guidelines tips

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

The 7th character depends on whether the patient is in active treatment, not on who sees the patient. An aftercare Z code is not used for injury aftercare.

Guidelines I.C.19.aInjuries: application of 7th charactersRead the official text

T36-T65 codes already include the substance and the intent, so no additional external cause code is required. Do not code directly from the Table of Drugs and Chemicals.

Guidelines I.C.19.ePoisoning, adverse effects and the Table of DrugsRead the official text

Code first

If the underlying condition listed here is present and known, sequence it first.

Also from chapter/block level (7 notes)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • , 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 the listed code as a secondary code, if known.

Also from chapter/block level (5 notes)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • 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-)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • code to identify any retained foreign body, if applicable (Z18.-)

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (1 note)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • toxic reaction to local anesthesia in pregnancy (O29.3-)

Excludes2

Not included here. Both codes may be reported if the patient has both conditions.

Inherited from T40 Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens]
  • drug dependence and related mental and behavioral disorders due to psychoactive substance use (F10.-F19.-)
Also from chapter/block level (7 notes)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • 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)
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • birth trauma (P10-P15)
  • obstetric trauma (O70-O71)

Includes

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

Also from chapter/block level (4 notes)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • 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

Conditions classified to this code.

This code
  • Poisoning by other synthetic narcotics NOS

Notes

Also from chapter/block level (3 notes)
Inherited from T36–T50 Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances
  • 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.
Inherited from Chapter 19 Injury, poisoning and certain other consequences of external causes
  • 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 codes under T40.491 3