Hallucinogens are a broad group of drugs that cause profound distortions in a person's perception of reality. Hallucinogens can also cause physiological symptoms such as increased heart rate and blood pressure, and may induce convulsions and seizures when used at high doses.
The prototype hallucinogen is LSD (Lysergic Acid Diethylamide). LSD can cause potent sensory perceptions, such as visual, auditory, and tactile hallucinations. Related hallucinogens include peyote and mescaline.
For more information on common hallucinogens, click here.