2027 ICD-10-CM Diagnosis Code T45Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified

ICD-10-CM Codes›S00–T88›T36-T50›T45

ICD-10-CM T45
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T45 is a non-billable ICD-10-CM category code for poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified, so it cannot be submitted on claims. Use a more specific code from this category instead, such as T45.0X1A, T45.0X1D, T45.0X1S, and T45.0X2A.

Code Identity

ICD-10-CM Code
T45
Billable Status
No — Non-Billable Category
Code Describes
Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified
Short Description
Primarily systemic and hematological agents, NEC
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
CategoryT45Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified
This CodeT45Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified

Specific Coding for Primarily systemic and hematological agents, NECOverview

Non-specific codes like T45 require more characters. Use one of these billable codes instead:

  • T45.0 for Poisoning by, adverse effect of and underdosing of antiallergic and antiemetic drugs

  • T45.0X for Poisoning by, adverse effect of and underdosing of antiallergic and antiemetic drugs

  • T45.1 for Poisoning by, adverse effect of and underdosing of antineoplastic and immunosuppressive drugs

  • T45.1X for Poisoning by, adverse effect of and underdosing of antineoplastic and immunosuppressive drugs

  • T45.2 for Poisoning by, adverse effect of and underdosing of vitamins

  • T45.2X for Poisoning by, adverse effect of and underdosing of vitamins

  • T45.3 for Poisoning by, adverse effect of and underdosing of enzymes

  • T45.3X for Poisoning by, adverse effect of and underdosing of enzymes

  • T45.4 for Poisoning by, adverse effect of and underdosing of iron and its compounds

  • T45.4X for Poisoning by, adverse effect of and underdosing of iron and its compounds

  • T45.5 for Poisoning by, adverse effect of and underdosing of anticoagulants and antithrombotic drugs

  • T45.51 for Poisoning by, adverse effect of and underdosing of anticoagulants

  • T45.52 for Poisoning by, adverse effect of and underdosing of antithrombotic drugs

  • T45.6 for Poisoning by, adverse effect of and underdosing of fibrinolysis-affecting drugs

  • T45.60 for Poisoning by, adverse effect of and underdosing of unspecified fibrinolysis-affecting drugs

  • T45.61 for Poisoning by, adverse effect of and underdosing of thrombolytic drugs

  • T45.62 for Poisoning by, adverse effect of and underdosing of hemostatic drugs

  • T45.69 for Poisoning by, adverse effect of and underdosing of other fibrinolysis-affecting drugs

  • T45.7 for Poisoning by, adverse effect of and underdosing of anticoagulant antagonists, vitamin K and other coagulants

  • T45.7X for Poisoning by, adverse effect of and underdosing of anticoagulant antagonists, vitamin K and other coagulants

  • T45.8 for Poisoning by, adverse effect of and underdosing of other primarily systemic and hematological agents

  • T45.8X for Poisoning by, adverse effect of and underdosing of other primarily systemic and hematological agents

  • T45.9 for Poisoning by, adverse effect of and underdosing of unspecified primarily systemic and hematological agent

  • T45.91 for Poisoning by unspecified primarily systemic and hematological agent, accidental (unintentional)

  • T45.92 for Poisoning by unspecified primarily systemic and hematological agent, intentional self-harm

  • T45.93 for Poisoning by unspecified primarily systemic and hematological agent, assault

  • T45.94 for Poisoning by unspecified primarily systemic and hematological agent, undetermined

  • T45.95 for Adverse effect of unspecified primarily systemic and hematological agent

  • T45.96 for Underdosing of unspecified primarily systemic and hematological agent

  • T45.A for Poisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs

  • T45.AX for Poisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs

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 primarily systemic and hematological agents, not elsewhere classified (T45). 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 T45: 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.

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 T45
Values for category T45 Encounter: Initial, Subsequent, Sequela
  • 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 T45Overview

Is T45 a billable code?

No. This is a category header that groups the codes for poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified, and headers cannot be submitted on claims. Claims for poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified need a more specific code from this category, such as T45.0X1A, T45.0X1D, and T45.0X1S.

Can T45 be reported with a code from O29.3?

Not as a rule. The Excludes1 note at block T36-T50, which applies to T45, 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).