Substance Index

Psychedelics (also known as serotonergic hallucinogens) are a subclass of hallucinogen that change perception, emotion, and thought. The user usually stays aware that a drug causes the experience. Researchers think that psychedelics act mainly on a serotonin receptor called 5-HT2A, which loosens the normal filtering of incoming information in the brain. Common effects are stronger color, flowing geometric patterns, deeper emotion, and a sense of insight. The term dates from 1956. It comes from the Greek psyche ("mind") and delos ("to reveal"), and means "mind-manifesting."