What is a primary characteristic of hallucinations in the context of hallucinogen use?

Hallucinations, particularly in the context of hallucinogen use, are primarily characterized by sensory experiences that are not based in reality. When an individual uses hallucinogenic substances, their perception of the world can be altered significantly, leading to vivid experiences that may involve seeing, hearing, or feeling things that do not actually exist. These experiences can range from mild alterations in perception to complex visual or auditory illusions.

This characteristic is crucial to understanding both the psychological impact of hallucinogens and the nature of the experiences users undergo. While excessive perspiration, confusion about surroundings, and creating irrational fears may be associated with other aspects of drug use or different substances, they do not define the primary experience of hallucinations like the perception of non-existent sensory inputs does. Thus, the key feature of hallucinations in this context is the presence of these false sensory experiences.