Hallucinogens are a class of substances that alter a person's perception, mood, and cognitive processes. These drugs can cause users to experience vivid visual and auditory hallucinations, as well as changes in thought patterns. Common hallucinogens include LSD, psilocybin (found in certain mushrooms), and DMT. They are often used recreationally but can also have therapeutic applications in controlled settings. The effects of hallucinogens can vary widely depending on the substance, dosage, and individual factors such as mood and environment. While some users report positive experiences, others may encounter negative effects, including anxiety or paranoia. Due to their powerful effects, hallucinogens are often studied for their potential in treating mental health conditions like depression and PTSD.