Is ICD-10-CM code T45 billable?

No, T45 (Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code T45 belong to?

T45 belongs to Chapter 19 of the ICD-10-CM tabular list: S00–T88 (Injury, Poisoning and Certain Other Consequences of External Causes).

T45Not billable, use a more specific code below

Poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified

In Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50), chapter 19: Injury, Poisoning and Certain Other Consequences of External Causes

270 billable codes under T45: none are a CC or MCC; 15 map to HCC 155 (Major Depression, Moderate or Severe, without Psychosis).An HCC counts toward a Medicare Advantage patient's risk score.

Instructional notes

Also applies, from Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances (T36-T50)

These notes sit on T36-T50 and apply to every code under it, including T45.

Includes: conditions that are coded here

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, use a different code

toxic reaction to local anesthesia in pregnancy (O29.3-)

Excludes2: not included here, code separately if applicable

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: code the underlying condition first, then 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: add a second code for this, listed after this one

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-)

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Section I.C.19.e Adverse Effects, Poisoning, Underdosing and Toxic Effects (page 82), covers T45
For adverse effects, code the effect first, then T36-T50 with character 5. Sequence poisonings (unknown intent coded accidental) and toxic effects (T51-T65) first; underdosing (character 6) is never first-listed.

All codes under T45

T45 can't be used on a claim. Pick a billable code below; grey headings group them.

T45 MS-DRGs

As the principal diagnosis, the billable codes under T45 group to these 9 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 949 Aftercare with CC/MCC (105 of 270 codes)
DRG 950 Aftercare without CC/MCC (105 of 270 codes)
DRG 917 Poisoning and Toxic Effects of Drugs with MCC (75 of 270 codes)
DRG 918 Poisoning and Toxic Effects of Drugs without MCC (75 of 270 codes)
DRG 922 Other Injury, Poisoning and Toxic Effect Diagnoses with MCC (75 of 270 codes)
DRG 923 Other Injury, Poisoning and Toxic Effect Diagnoses without MCC (75 of 270 codes)
DRG 791 Prematurity with Major Problems (15 of 270 codes)
DRG 793 Full Term Neonate with Major Problems (15 of 270 codes)
DRG 951 Other Factors Influencing Health Status (15 of 270 codes)

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Drug Reactions

Most of the time, medicines make our lives better. They reduce aches and pains, fight infections, and control problems such as high blood pressure or diabetes. But medicines can also cause unwanted reactions, such as drug interactions, side effects, and allergies.

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.