T45.AXPoisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs

T45.AX is the ICD-10-CM diagnosis code for poisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs. It belongs to category T45 (poisoning by, adverse effect of and underdosing of primarily systemic and hematological agents, not elsewhere classified), block T36-T50 (poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 6 subcodes must be used instead.

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It was added in FY2025, effective October 1, 2024.