A
Afterglow
A period of elevated mood, openness, and mental clarity that can follow a psychedelic experience, typically lasting days to a couple of weeks. The afterglow window is considered especially valuable for integration work.
B
Bad trip
Colloquial term for a frightening or distressing psychedelic experience. Many practitioners prefer challenging experience, since difficulty and harm are not the same thing — survey research finds most people rate their hardest journeys among their most meaningful.
Blotter
Perforated absorbent paper onto which liquid LSD has been applied, divided into individual "tabs." Because dosage per tab is unverifiable without testing, blotter strength varies widely between sources.
Body load
The physical sensations accompanying a substance — heaviness, tension, nausea, temperature shifts. Substances differ markedly in body load; mescaline and ayahuasca are known for heavy ones, LSD for a stimulating one.
Breakthrough
In DMT use, the point at which the experience shifts from altered perception to a complete replacement of ordinary reality, often described as entering another space. Used as a rough dose threshold in DMT contexts.
C
Challenging experience
A psychedelic experience involving significant fear, grief, confusion, or psychological struggle. Distinct from a harmful experience: with support and integration, challenging material is frequently reported as the most valuable part of psychedelic work. See our crisis resources for real-time support.
Closed-eye visuals (CEVs)
Imagery perceived with eyes closed during a psychedelic experience, ranging from geometric patterns to elaborate scenes. Contrast with open-eye visuals.
Come-up
The transition period between ingestion and peak effects, often accompanied by anxiety, nausea, or restlessness. Knowing a substance's expected come-up duration helps distinguish normal onset from something wrong.
Comedown
The gradual return to baseline as effects fade. Some substances (notably MDMA) can involve a post-experience dip in mood over following days as neurotransmitter systems rebalance.
Container
The deliberate structure holding an experience: the space, the people present, agreements made beforehand, and plans for what happens after. A strong container is a core element of preparation and of any well-run ceremony.
Cross-tolerance
Reduced response to one substance caused by recent use of another acting on the same receptors. Classical psychedelics (LSD, psilocybin, mescaline) are strongly cross-tolerant: taking one shortly after another produces diminished effects.
D
Decriminalization
Removal of criminal penalties for personal possession or use — typically replaced with civil penalties or nothing. Distinct from legalization: production and sale remain illegal. See Law for the full distinction.
Default mode network (DMN)
A set of interconnected brain regions active during self-referential thought — rumination, autobiographical memory, mental time travel. Psychedelics acutely reduce DMN integrity, which some researchers link to ego dissolution, though the full picture is more complex. See Science.
Dieta
In Amazonian ayahuasca traditions, a period of dietary and behavioral restriction (avoiding salt, sugar, alcohol, sexual activity, certain foods) undertaken before and after ceremony — both a spiritual discipline and, in part, a practical safety measure given MAOI interactions.
Dissociative
A class of substances — including ketamine, nitrous oxide, and DXM — producing detachment from body and environment, primarily via NMDA receptor antagonism. Pharmacologically distinct from classical psychedelics, with distinct risks including dependence.
Dose–response
The relationship between the amount taken and the intensity of effects. Psychedelic dose–response curves are steep: modest increases in dose can produce qualitatively different experiences, which is why careful measurement matters.
E
Ego dissolution
The temporary weakening or loss of the ordinary sense of being a separate self, common at higher doses of classical psychedelics. Can be experienced as liberating union or as terrifying annihilation — preparation and surrender strongly shape which.
Empathogen / entactogen
A class of substances — MDMA foremost — producing emotional openness, closeness, and reduced fear rather than classical psychedelic perception changes. The term entactogen ("touching within") was coined to avoid the implication that empathy is guaranteed.
Entheogen
A term ("generating the divine within") for psychoactive substances used in spiritual or religious contexts. Preferred by some to "psychedelic" or "hallucinogen" to emphasize sacramental rather than recreational framing.
Entity encounter
The experience of meeting apparently autonomous beings during a psychedelic experience, most commonly reported with DMT. Whatever their ontological status, such encounters are frequently rated as profoundly meaningful and can carry lasting belief changes.
F
Facilitator
A person who holds space for someone else's psychedelic experience — ranging from a trained professional in a legal program to an experienced peer. Competence, ethics, and consent practices vary enormously; see Facilitation and our article on finding a trustworthy guide.
G
Good Samaritan law
Legislation protecting people who call emergency services during a drug-related emergency from prosecution for simple possession. Most US states and Canada have some version. Never let legal fear delay a call for help — see Crisis Resources.
Grounding
Techniques for reconnecting with the body and immediate environment during overwhelming states: slow breathing, feeling the floor, holding a familiar object, naming things you can see. A core skill in navigation.
Guide
Often used interchangeably with facilitator; sometimes specifically a person who takes a more active, directive role in shaping the journey, as opposed to a sitter, who mainly ensures safety.
H
Harm reduction
A public health approach that reduces the risks of drug use without requiring abstinence — through education, testing, safer practices, and support. The orienting philosophy of this entire site.
Heroic dose
Terence McKenna's term for a very high dose taken in darkness and silence — conventionally five grams of dried psilocybin mushrooms. The framing is romantic; the risk profile is real. High doses amplify both benefit and harm and warrant serious assessment.
HPPD
Hallucinogen Persisting Perception Disorder: ongoing perceptual disturbances (visual snow, trails, halos) persisting long after use, causing distress or impairment. Rare, more likely with frequent use, and a reason people with certain visual or neurological conditions should be cautious.
I
Ineffability
The sense that an experience cannot be adequately put into words — a hallmark quality of mystical experiences. Worth trying anyway: articulating the inarticulable is much of what integration is.
Integration
The deliberate process of translating a psychedelic experience into lasting understanding and changed behavior — through reflection, journaling, conversation, therapy, and practice. Widely considered the phase where most of the actual benefit is realized. See Integration.
Intention
The question, theme, or orientation a person brings to an experience — "what am I here to look at?" Distinct from an expectation or demand; intentions steer without scripting. Central to preparation.
J
Journey
A common term for a full psychedelic experience, emphasizing its arc — departure, unfamiliar territory, return — over its pharmacology. This site's Journey Planner is built around that arc.
M
Macrodose
A full, perceptually active dose — the ordinary sense of "taking a psychedelic" — as opposed to a microdose.
MAOI
Monoamine oxidase inhibitor — a compound that blocks the enzymes breaking down serotonin, dopamine, and related molecules. The harmala alkaloids in ayahuasca are MAOIs, which is what makes oral DMT active — and what makes ayahuasca dangerous to combine with many medications and foods. Check the Interaction Checker.
Microdose
A sub-perceptual dose — commonly around one-tenth to one-twentieth of a macrodose — taken on a repeating protocol with the aim of subtle benefits rather than an altered state. Evidence is mixed and expectation effects are substantial; see Microdosing.
Mystical experience
A cluster of experience qualities — unity, sacredness, deep positive mood, transcendence of time and space, ineffability — measured in research by validated questionnaires. In several trials, mystical-experience scores predicted the durability of clinical benefit.
N
Neuroplasticity
The brain's capacity to reorganize connections. Psychedelics promote markers of structural and functional plasticity in preclinical studies — one hypothesis for why they may open a window in which new patterns are easier to establish, and why integration matters.
O
Onset
The time from ingestion to first noticeable effects. Varies by substance and route — minutes for vaporized DMT, up to two hours for oral mescaline. Redosing before onset completes is a classic and avoidable error.
Open-eye visuals (OEVs)
Perceptual changes with eyes open: breathing surfaces, color intensification, pattern overlay. Generally not true hallucinations — the person knows the wall isn't actually moving.
P
Peak
The period of maximum intensity, following the come-up. Timing the environment, support, and any planned practices around the peak is a core part of session design.
Plant medicine
A term for psychoactive plants and fungi used in healing contexts — ayahuasca, peyote, psilocybin mushrooms, iboga. Signals a relational, traditional framing; also critiqued when used to market substances far removed from any tradition.
Psilocin
The active compound in psilocybin mushrooms. Psilocybin itself is a prodrug — the body converts it to psilocin, which acts on serotonin 5-HT2A receptors. See Psilocybin.
Psychedelic-assisted therapy
A treatment model pairing one or a few high-dose sessions with structured psychotherapy before and after. The model used in most modern clinical trials — the substance is understood as a catalyst within therapy, not a standalone medication.
Psycholytic therapy
An older European model using repeated low-to-moderate doses within ongoing talk therapy, keeping the patient conversational — in contrast to the high-dose, inward-focused psychedelic model.
R
Reactivation
A spontaneous, temporary return of experience-like states in the days after a session — most reported after 5-MeO-DMT. Usually brief and benign; unsettling if unexpected, which is why good facilitators mention it beforehand.
Retreat
A multi-day residential format for psychedelic work, typically including preparation, one or more ceremonies, and group integration. Quality and safety vary drastically — vet the operator, the medical screening, and the facilitator-to-participant ratio.
S
Schedule I
The most restrictive category under the US Controlled Substances Act and the UN convention system — defined as having no accepted medical use and high abuse potential. Most classical psychedelics remain Schedule I federally regardless of state-level reform. See Law.
Serotonin syndrome
A potentially life-threatening condition caused by excess serotonergic activity — agitation, muscle rigidity or twitching, fever, racing heart. The key risk behind combining serotonergic substances (e.g., MAOIs with MDMA or with many antidepressants). It is a medical emergency: see Crisis Resources.
Set and setting
The two great non-drug determinants of a psychedelic experience: set — your mindset, mood, intentions, and psychological state — and setting — the physical and social environment. The foundational concept of psychedelic harm reduction. See our set and setting checklist.
Sitter (trip sitter)
A sober person present during someone's experience whose primary role is safety and reassurance rather than guidance. The minimum standard of care for high-dose work. See Facilitation.
Stacking
Combining a microdose with putative synergists — most famously the "Stamets stack" of psilocybin, lion's mane, and niacin. Popular; essentially untested in controlled research.
Sub-perceptual
Below the threshold of noticeable acute effects — the defining property of a true microdose. If you clearly feel it, it isn't one.
Synesthesia
Blending of the senses — seeing sound, tasting color — commonly reported during psychedelic experiences even by people who never experience it otherwise.
T
Threshold dose
The smallest dose producing any detectable effect. Useful as a calibration point when working with unfamiliar substances or batches — start below it, not above it.
Tolerance
Diminished response with repeated use. Classical psychedelic tolerance builds within hours and takes roughly one to two weeks to reset — one reason spacing sessions is both a safety and an efficacy practice. See also cross-tolerance.
Trip killer
A medication — most often a benzodiazepine — used to blunt or end a psychedelic experience. A genuine option in severe distress under medical guidance, but not a casual safety net: sourcing, dosing, and combination risks are all serious. Non-pharmacological grounding resolves most difficulty.