Hallucinogens are a class of drugs that alter an individual's perception, thoughts, and feelings. These substances are also commonly known as psychedelics, which can induce deep psychological impact and sensory distortion. Other synonyms for hallucinogens include mind-altering substances, psychotropics, hallucinogenic substances, and psychoactive drugs. These drugs can be derived from plants, fungi, or be synthesized in a laboratory. Common examples of hallucinogens include LSD, psilocybin mushrooms, peyote, DMT, and MDMA. While classified as illegal substances, some hallucinogens have been approved for medical use in treating mental health disorders such as depression, anxiety, and post-traumatic stress disorder.