T45.AX4Poisoning by immune checkpoint inhibitors and immunostimulant drugs, undetermined

T45.AX4 is the ICD-10-CM diagnosis code for poisoning by immune checkpoint inhibitors and immunostimulant drugs, undetermined. 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 3 subcodes must be used instead.

Within T45.AX (poisoning by, adverse effect of and underdosing of immune checkpoint inhibitors and immunostimulant drugs), T45.AX4 is specifically for poisoning by immune checkpoint inhibitors and immunostimulant drugs, undetermined. Related codes cover poisoning by immune checkpoint inhibitors and immunostimulant drugs, accidental (unintentional) (T45.AX1), poisoning by immune checkpoint inhibitors and immunostimulant drugs, intentional self-harm (T45.AX2), poisoning by immune checkpoint inhibitors and immunostimulant drugs, assault (T45.AX3), adverse effect of immune checkpoint inhibitors and immunostimulant drugs (T45.AX5) and underdosing of immune checkpoint inhibitors and immunostimulant drugs (T45.AX6).

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.