Hallucinogens are a group of drugs that change a person’s awareness of their surroundings,  thoughts, and feelings. Hallucinogens can cause hallucinations and can lead to numbness;  disorientation and loss of coordination; and increased blood pressure, heart rate, and body  temperature. Long-term effects of hallucinogens can include speech problems, memory loss,  anxiety, and depression and suicidal thoughts. Hallucinogens include MDMA, magic  mushrooms, and LSD.