Psychedelics
Psychedelics are psychoactive substances that can alter perception, mood, thought, and a person's sense of time or self. The term most often refers to classic serotonin-acting drugs such as psilocybin, LSD, mescaline, and DMT, though everyday usage can include related substances.
- Main effect
- Changes in perception and thought
- Classic examples
- Psilocybin, LSD, mescaline, DMT
- Brain target
- Often the serotonin 5-HT2A receptor
- Legal status
- Varies; psilocybin is federally Schedule I
- Mushroom link
- Some species contain psilocybin
What are psychedelics?
Psychedelics are mind-altering substances known for changing how a person perceives sights, sounds, emotions, thoughts, or time. The word usually describes classic psychedelics, including psilocybin, LSD, mescaline, and DMT. These substances can produce a wide range of experiences, from subtle shifts in attention to intense changes in a person's sense of self. They do not necessarily cause clear-cut visions or the same effects in everyone.
In scientific writing, classic psychedelics are often grouped by their effects on serotonin signaling, especially activity involving the 5-HT2A receptor. Chemists also sort many of them into families such as tryptamines, phenethylamines, and lysergamides. Everyday use of the word is sometimes broader: people may include drugs such as ketamine or MDMA, even though those substances work differently and are usually placed in other drug categories.
- 1Enter circulation
After exposure, a substance enters the body and becomes available to reach the brain.
- 2Reach the brain
The compound or an active form crosses into the brain's signaling environment.
- 3Bind receptors
Many classic psychedelics interact with serotonin 5-HT2A receptors.
- 4Change signaling
Receptor activity influences communication across circuits involved in perception and cognition.
- 5Experience shifts
The combined changes may alter perception, mood, thought, or sense of time.
How do psychedelics affect the brain?
Many classic psychedelics interact with serotonin receptors in the brain. Serotonin is a chemical messenger involved in several brain functions, and the 5-HT2A receptor is a key site of action for this group. Receptor activity can change how brain networks handle information, but researchers have not fully explained how those changes produce particular thoughts, images, or feelings.
The experience is shaped by more than a molecule's receptor activity. The specific substance, a person's expectations and surroundings, and individual differences can all matter. Effects may include altered sensory perception, shifts in mood, unusual associations, or a changed sense of time. These descriptions are not a prediction of what any one person will experience, and the broad label “psychedelic” does not mean every substance has the same effects.
The category includes naturally occurring and lab-made substances.
The term usually means classic psychedelics, but can include adjacent drugs.
Effects differ by substance, person, and circumstances.
Editorial placement to help compare; not a measurement.
Where do people encounter psychedelics?
People encounter psychedelics in research, cultural and religious traditions, public discussion, and recreational settings. Some Indigenous communities have long-standing ceremonial relationships with particular psychoactive plants or fungi. Those traditions have their own histories and meanings; they are not interchangeable with modern recreational use. In scientific settings, researchers study psychedelic experiences and their possible applications, but ongoing investigation is not proof that a substance is an established medical treatment.
In the United States, psilocybin remains Schedule I under federal law. State rules can differ: Oregon and Colorado have state-regulated programs for supervised access, while New Mexico's medical program is being set up. These programs do not change psilocybin's federal status or make it generally legal to possess. Rules for other psychedelic substances also vary, so check current official sources rather than assuming one state's policy applies elsewhere.
| Psychedelics | Dissociatives | Entactogens | |
|---|---|---|---|
| Typical effect | Shifts in perception and thought | Detachment or altered awareness | Increased emotional openness |
| Example | Psilocybin or LSD | Ketamine | MDMA |
| Common action | Often involves 5-HT2A receptors | Often involves NMDA receptors | Often affects serotonin signaling |
| Categories | Classic hallucinogens | Dissociative anesthetics | Entactogenic substances |
What are common misconceptions and safety concerns?
A common misconception is that all psychedelics are interchangeable, or that every psychedelic is a mushroom compound. Psilocybin is found in some mushrooms, but LSD, mescaline, and DMT come from different sources or are made differently. Amanita mushrooms are another distinct case: their main intoxicating compounds are not psilocybin, and their effects differ from those of classic serotonin-linked psychedelics.
Psychedelic experiences can be distressing or disorienting, and impaired judgment can create risks in unfamiliar or unsafe surroundings. Some people report lasting perceptual changes after use, and intense psychological effects are a concern. Unregulated products may also be mislabeled or contain unexpected substances. Never eat a wild mushroom without expert identification; a mistaken identification can be dangerous, and appearance alone is not a reliable safety test.
- 1943
Albert Hofmann recognized LSD's psychoactive effects.
- 1956
Humphry Osmond introduced the term “psychedelic.”
- 1958
Albert Hofmann isolated and named psilocybin and psilocin.
- 1970
The U.S. Controlled Substances Act established Schedule I, including psilocybin and LSD.
- 2020
Oregon voters approved Measure 109, creating a state psilocybin services program.
How do psychedelics connect to mushroom science?
The clearest mushroom connection is psilocybin, a compound produced by certain fungi, including species in the genus Psilocybe. After a person takes psilocybin, the body converts much of it into psilocin, a related compound that contributes to its effects. Mushroom research also covers identification, ecology, and how fungi grow. These topics help explain where psilocybin occurs, but they do not make every mushroom with a similar appearance safe or psychoactive.
For readers learning mushroom terms, it helps to distinguish the organism from its chemistry: a mushroom is a fungal structure, while psilocybin is one chemical some fungi produce. Species identification requires attention to multiple features and context, not a quick image match. Topics such as mycelium, spores, and the mushroom life cycle describe fungal biology; topics such as serotonin receptors and psychedelic experiences describe effects in people. Keeping those subjects separate makes mushroom science easier to understand.
Common questions about Psychedelics
What are psychedelics?
Psychedelics are psychoactive substances that can change perception, thought, mood, or a person's sense of time and self. The word commonly refers to classic substances such as psilocybin, LSD, mescaline, and DMT. Their effects vary, and the term is sometimes used more broadly for related drugs.
Are psychedelics the same as hallucinogens?
The terms overlap, but they are not always used identically. Psychedelics are often called classic hallucinogens because they can alter perception and thought. “Hallucinogen” is a broader label that may include substances with different effects and mechanisms, including dissociatives and deliriants.
Are psychedelics legal in the United States?
Legality depends on the substance and location. Psilocybin is federally Schedule I. Oregon and Colorado have state-regulated supervised access programs, and New Mexico's medical program is being set up; these state policies do not remove federal restrictions. Check current government sources for the rules where you live.
Are psychedelic mushrooms safe to identify by appearance?
No. Some wild mushrooms can resemble other species, and appearance alone cannot reliably establish identity or safety. Never eat a wild mushroom without expert identification. Psilocybin-containing mushrooms also vary by species, while poisonous lookalikes can cause serious harm.
Related terms
Explore on Pscilly
Sources and further reading
Written by the Pscilly editorial team and reviewed November 2026. Educational content only, not medical or legal advice. Pscilly does not sell psilocybin. Never eat a wild mushroom without expert identification.