A hallucinogen is a drug or chemical substance that alters perception and sense of reality, causing hallucinations. Common hallucinogens include LSD (d-lysergic acid diethylamide), or “acid,” Peyote, Psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine), also known as “magic mushrooms” or “shrooms,” PCP (phencyclidine), known as “ozone, rocket fuel, love boat,” and Ketamine, or “K or “Special K.” Hallucinogetic compounds found in some plants and mushrooms (or their extracts) have been used for centuries—mostly in religious ceremonies, healing rituals, worship, mystical insight or battle. Peyote is possibly the oldest hallucinogen used by mankind, reportedly used more than 5,000 years ago. Today, they are widely abused in the United States: More than 180,000 Americans aged 12 and older reported current (past- month) use of LSD and 32,000 reported current use of PCP, according to the 2012 National Survey on Drug Use and Health. Under the influence of hallucinogens, people see images, hear sounds and feel sensations that seem real but are not. Some hallucinogens also produce severe emotional, behavioral, cognitive, physical and psychotic side effects, which may lead to withdrawal symptoms and disturbances or corruption of critical bodily systems including the respiratory, cardiovascular and central nervous systems. Overdose can result in coma or death.