deliriant

A deliriant is a substance that induces delirium—a state of confusion, disorientation, and hallucinations that the user often cannot distinguish from reality.

Unlike psychedelics, which typically produce recognizable hallucinations, deliriants create experiences that seem genuinely real: conversations with people who aren't there, mundane activities that never happened.

Common deliriants include diphenhydramine (Benadryl) in high doses and datura.

The term also works as an adjective: deliriant effects, deliriant poisoning.