T45.91XA ICD-10-CM Code: Poisoning by unspecified primarily systemic and hematological agent, accidental (unintentional), initial encounter
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.
- MS-DRG 917 — POISONING AND TOXIC EFFECTS OF DRUGS WITH MCC (MDC 21)
- MS-DRG 918 — POISONING AND TOXIC EFFECTS OF DRUGS WITHOUT MCC (MDC 21)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for T45.91XA 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 primarily systemic and hematological agent 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.
- 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.
- 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
Supplementary codes the tabular list directs you to add.
- Use additional 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 T45.91XA require a 7th character?
Yes. The appropriate 7th character is to be added to each code from category T45.
Nearest Codes in This Family
Official ICD-10-CM classifications closest to T45.91XA in its code family, with their registry titles.
- T45.8X6A — Underdosing of other primarily systemic and hematological agents, initial encounter
- T45.8X6D — Underdosing of other primarily systemic and hematological agents, subsequent encounter
- T45.8X6S — Underdosing of other primarily systemic and hematological agents, sequela
- T45.9 — Poisoning by, adverse effect of and underdosing of unspecified primarily systemic and hematological agent
- T45.91 — Poisoning by unspecified primarily systemic and hematological agent, accidental (unintentional)
- T45.91XD — Poisoning by unspecified primarily systemic and hematological agent, accidental (unintentional), subsequent encounter
- T45.91XS — Poisoning by unspecified primarily systemic and hematological agent, accidental (unintentional), sequela
- T45.92 — Poisoning by unspecified primarily systemic and hematological agent, intentional self-harm
- T45.92XA — Poisoning by unspecified primarily systemic and hematological agent, intentional self-harm, initial encounter
- T45.92XD — Poisoning by unspecified primarily systemic and hematological agent, intentional self-harm, subsequent encounter