Which term describes a mental state with altered sensory perception often accompanied by hallucinations?

The term that accurately describes a mental state with altered sensory perception often accompanied by hallucinations is "psychedelic." Psychedelic substances, which include various hallucinogens, are known for their ability to significantly alter perception, mood, and cognitive processes. Users may experience visual and auditory hallucinations, as well as a profound change in their sense of reality. This relates directly to the definition, making "psychedelic" the most fitting choice for the description provided in the question.

In contrast, "psychomimetic" refers to substances that mimic the effects of psychosis, but not exclusively to sensory perception changes or hallucinations. "Psychogenic" generally describes conditions or phenomena that are derived from psychological rather than physical causes, which does not necessarily indicate the specific sensory alterations present in the context of psychedelics. "Paranoia," while a mental state that can occur in various contexts, specifically refers to feelings of distrust or suspicion, rather than the broader alterations in perception associated with hallucinations.