Hallucinogens like LSD are known for what primary effect?

Hallucinogens like LSD primarily cause hallucinations, which are perceptions of things that are not present in the environment. These substances alter the user's sensory experiences, leading to distorted perceptions of reality, visual and auditory hallucinations, and significant changes in mood and thought processes. The use of hallucinogens influences neurotransmitter systems in the brain, particularly serotonin receptors, which affects how sensory information is processed. This property of inducing hallucinations is a hallmark characteristic of hallucinogenic substances and distinguishes them from other drug categories.

While increased heart rate and slowed reflexes may occur due to various factors related to drug use or the physiological response to different substances, they are not primary effects associated with LSD. Similarly, memory loss is not a defining feature of LSD usage compared to its more prominent effects such as hallucinations.