Hallucinogens usually cause an elevation of the systolic blood pressure, dilatation of the pupils, some facilitation of the spinal reflexes, and excitation of the sympathetic nervous system. In addition, hallucinogens can lead to increased heart rate and blood pressure, sleepiness and tremors, lack of muscle coordination, incoherent speech, decreased awareness of touch and pain, coma, heart and lung failure, and even death.
Hallucinogens are associated with a disruption of the sense of distance and estrangement, depression, anxiety, paranoia, violent behaviors, confusion, suspicion, loss of control, flashbacks, psychosis, lethargic and disorientation.
LSD is chemically similar to the neurotransmitter serotonin. An LSD trip can vary from euphoria to detachment to panic. The hallucinations typically begin with geometric forms, then to more meaningful images, and then the user often feels separate from their body and experience dreamlike scenes that feel so real.
Consisting from leaves and flowers of the hemp plant, marijuana's major active ingredient THC produces a mix of effects. It relaxes, disinhibits, and may produce a euphoric high. It amplifies sensitivity to colors, sounds, tastes, and smells. THC lingers in the body for over a month. Marijuana intensifies feelings and emotions, whether happy, sad, anger, or another. It disrupts memory formation and interferes with immediate recall of information.