Psilocin
4-hydroxy-N,N-dimethyltryptamine
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Psilocin (4-hydroxy-N,N-dimethyltryptamine) is a naturally-occurring psychedelic of the tryptamine class. It is the active form of psilocybin — the compound responsible for the effects of magic mushrooms. It activates serotonin receptors in the brain,[1] disrupting normal sensory filtering and producing the visual, emotional, and cognitive shifts characteristic of classical psychedelics.
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Albert Hofmann isolated psilocin at Sandoz Laboratories in 1958–1959 while characterizing Psilocybe mushroom alkaloids.[2] Schedule I placement in 1970 ended clinical research for nearly four decades, until a 2006 Johns Hopkins trial reignited scientific interest.[3] Oregon now permits supervised therapeutic access, and Australia has authorized medical prescription for treatment-resistant depression.[4]
Subjective effects include geometric visual patterns, ego dissolution, emotional intensification, brightened colors, time alteration, and episodes of profound meaning.[5] More than most psychedelics, the quality of the experience is shaped by mindset, intention, and physical surroundings — context matters as much as dose. Nausea during onset, transient anxiety, and thought loops are common unsought effects.
Psilocin produces no physical dependence and no withdrawal, and no human death from psilocin overdose alone has been reported.[6] The primary risk is psychological: challenging experiences scale with dose and predisposition, while rapid tolerance makes compulsive redosing self-limiting.[7] Seven decades of research give psilocin an unusually well-characterized safety profile for a psychedelic, though aspects of its metabolism remain incompletely understood.[8]
History[edit]
Discovery
R. Gordon Wasson's 1957 account of Psilocybe ceremonies in Oaxaca, Mexico brought the fungi to Western scientific attention. Albert Hofmann isolated psilocybin from cultivated mushrooms in 1958[9] and identified psilocin as its active metabolite the following year.[2]
Prohibition and the research gap
Sandoz marketed psilocybin for psychiatric research through the early 1960s, but rising recreational use triggered a ban. Psilocin and psilocybin entered US Schedule I in 1970, and the 1971 UN Convention extended prohibitions internationally. Research effectively ceased for three decades.
Modern renaissance
The revival began with Griffiths et al.'s 2006 trial at Johns Hopkins, showing psilocybin occasions meaningful experiences with lasting personal significance.[3] Rapid antidepressant effects were demonstrated in treatment-resistant depression,[10] followed by a Phase 2 trial published in the New England Journal of Medicine in 2022.[11] The FDA has since granted two Breakthrough Therapy Designations; Oregon and Australia now permit supervised or medical access.[12][4]
Psilocybe mushrooms have been used ceremonially by Mazatec and other Indigenous peoples of Mesoamerica for centuries. Wasson's fieldwork with curandera María Sabina in Huautla de Jiménez documented a living tradition in which mushrooms served as sacramental tools for divination and healing — a practice that continued despite colonial-era suppression.
The name psilocin derives from the Greek psilos (bare), coined by Hofmann to echo psilocybin. In common usage psilocin is rarely distinguished from psilocybin; both are simply "the active compound in magic mushrooms."
Chemistry[edit]
Structure
Psilocin belongs to the substituted tryptamine family — specifically the 4-hydroxytryptamine subclass. Its molecular formula is C₁₂H₁₆N₂O (204.27 g/mol). It is structurally close to serotonin, sharing the same indole-ethylamine backbone, which explains its affinity for serotonin receptors.
Psilocin is the active form of psilocybin: enzymes in the gut cleave the phosphate group on ingestion,[9] releasing psilocin into the bloodstream. It occurs naturally in over 200 fungal species, primarily within Psilocybe, Panaeolus, and Gymnopilus.
| Molecular formula | C₁₂H₁₆N₂O |
| Molecular weight | 204.27 g/mol |
Pharmacology[edit]
Mechanism of action
Psilocin produces its psychedelic effects by activating serotonin receptors in the brain. Blocking these receptors completely abolishes all psychedelic effects.[1][13] Psilocin also interacts with the SERT — a property unique among classical psychedelics[14] — contributing to its characteristic warmth and emotional openness.
TrkB binding — a second mechanism
Independent of its psychedelic effects, psilocin directly binds TrkB — the brain's main nerve-growth receptor — promoting the formation of new neural connections.[15] This plasticity mechanism operates independently of the hallucinogenic effects, raising the possibility that psilocin's antidepressant benefits may be separable from the psychedelic experience.[16]
Pharmacokinetics
When psilocybin is ingested, gut enzymes convert it almost entirely to psilocin before it reaches the bloodstream.[17] Oral bioavailability averages roughly 53%,[8] with peak blood levels occurring between 1.8 and 4 hours after ingestion[18] and an half-life of roughly 1.8 hours.[19] MAO-A handles over 80% of hepatic clearance,[20] though substantial breakdown also occurs outside the liver.
Neuroscience[edit]
Where it acts
Psilocin's most prominent brain effect is disruption of the default mode network — the system supporting the sense of a continuous self. This desynchronization correlates directly with the experience of ego dissolution.[21][22] Alongside this, organized brain oscillations drop sharply — an effect completely blocked by serotonin-receptor blockers.[1]
Why it matters
The REBUS framework proposes that psilocin loosens the brain's ingrained assumptions about the world, allowing sensory information to reshape entrenched patterns of thought.[23] This connects the subjective experience of dissolved certainty and novel perception to measurable changes in brain organization.[21]
Psilocin also promotes structural changes in the brain — growing and strengthening neural connections through two converging mechanisms.[15][16] These changes may explain why therapeutic benefits persist long after the drug has cleared the body. How long this plasticity window lasts after a single dose is not yet known.
Several fundamental questions remain unresolved. The duration of the enhanced plasticity window after a single dose has not been precisely determined. Whether psilocin's therapeutic effects can be achieved without the hallucinogenic experience is an active area of investigation.
Subjective Effects[edit]
Psilocin produces an experience defined by emotional depth. Colors sharpen, surfaces seem alive, and the boundary between self and surroundings begins to dissolve. Mood is permeable — joy, grief, and wonder can surface in close succession. Context shapes all of it; the same dose in different settings can feel entirely different.[5]
Compared to LSD, psilocin is shorter-acting, emotionally warmer, and less cognitively accelerating.[14] Compared to mescaline, it is more potent by weight and more inward-turning. This combination of emotional depth and moderate duration makes it particularly suited to therapeutic contexts.
Effect Grid
At common doses, the full psychedelic experience manifests: pronounced open-eye visual distortions including geometric patterning overlaying surfaces, drifting and morphing of objects, color shifting, and enhanced pattern recognition. Closed-eye visuals emerge as fractal imagery and flowing geometric landscapes. Time distortion becomes significant — minutes may feel like hours. Emotional intensification is marked, with enhanced empathy and deep introspection. Thought acceleration and novel conceptual connections are prominent.
Physically, nausea is common during onset (20–40 minutes), pupil dilation is pronounced, temperature dysregulation occurs (alternating warmth and chills), and body load or heaviness is typical. Yawning and lacrimation are characteristic.
Functional capacity for routine tasks is substantially impaired. The experience demands a committed 5–6 hour window with no responsibilities. Sleep is impossible during the active phase.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Geometry · Visual breathing · Tracers · Depth perception distortion · Environmental patterning · Music enhancement · Perspective distortion · Brightness alteration · Light sensitivity · Sound sensitivity · Visual morphing · Visual haze / noise · Visual diffraction · Symmetrical texture repetition · Touch enhancement · After-images · Auditory enhancement · Peripheral vision distortion · Spatial disorientation · Visual melting · Ganzfeld effect · Vestibular distortion · Synesthesia · Auditory distortion · Auditory misinterpretation · Proprioceptive distortion · Dreaming enhancement · Peripheral misidentification · Visual acuity enhancement · Taste enhancement · Visual magnification · Tinnitus · Visual acuity suppression · Olfactory enhancement · Flashbacks · Object transformations · Internal hallucinations · External hallucinations · Visual recursion · Object activation · Perspective hallucinations · Environmental orbism / cubism · Visual scenery slicing · Auditory hallucinations · Visual processing suppression · Visual flipping · Olfactory hallucination · Shadow people · Persisting hallucinations
Environmental patterning · Music enhancement · Perspective distortion · Brightness alteration · Light sensitivity · Sound sensitivity · Visual morphing · Visual haze / noise · Visual diffraction · Symmetrical texture repetition · Touch enhancement · After-images · Auditory enhancement · Peripheral vision distortion · Spatial disorientation · Visual melting · Ganzfeld effect · Vestibular distortion · Synesthesia · Auditory distortion · Auditory misinterpretation · Proprioceptive distortion · Dreaming enhancement · Peripheral misidentification · Visual acuity enhancement · Taste enhancement · Visual magnification · Tinnitus · Visual acuity suppression · Olfactory enhancement · Flashbacks · Object transformations · Internal hallucinations · External hallucinations · Visual recursion · Object activation · Perspective hallucinations · Environmental orbism / cubism · Visual scenery slicing · Auditory hallucinations · Visual processing suppression · Visual flipping · Olfactory hallucination · Shadow people · Persisting hallucinations
Body high · Nausea · Stimulation · Body schema distortion · Appetite suppression · Dizziness · Laughter fits · Excessive sweating · Headache · Heart rate perception changes · Physical fatigue · Restlessness · Tactile euphoria · Temperature dysregulation · Tingling / electric sensations · Yawning · Muscle tension · Sedation · Bodily heaviness · Bodily lightness · Bodily pressures · Breathing alteration · Dry mouth · Insomnia · Muscle relaxation · Trembling · Vibrations / buzzing · Wakefulness · Increased urination · Salivation · Watery eyes · Bruxism · Dehydration sensation · Involuntary body movements · Nystagmus (eye wobbles) · Pain suppression · Respiratory stimulation · Sexual arousal enhancement · Brain zaps · Nasal congestion · Diarrhea · Vasoconstriction · Vomiting · Seizure threshold reduction · Bodily dissociation · Tactile hallucination
Body schema distortion · Appetite suppression · Dizziness · Laughter fits · Excessive sweating · Headache · Heart rate perception changes · Physical fatigue · Restlessness · Tactile euphoria · Tingling / electric sensations · Yawning · Muscle tension · Sedation · Bodily heaviness · Bodily lightness · Bodily pressures · Breathing alteration · Dry mouth · Insomnia · Muscle relaxation · Trembling · Vibrations / buzzing · Wakefulness · Increased urination · Salivation · Watery eyes · Bruxism · Dehydration sensation · Involuntary body movements · Nystagmus (eye wobbles) · Pain suppression · Respiratory stimulation · Sexual arousal enhancement · Brain zaps · Nasal congestion · Diarrhea · Vasoconstriction · Vomiting · Seizure threshold reduction · Bodily dissociation · Tactile hallucination
Thought connectivity · Conceptual thinking · Immersion enhancement · Cognitive euphoria · Novelty enhancement · Pattern recognition enhancement · Aesthetic enhancement · Cognitive flexibility · Thought disorganization · Increased nature relatedness · Confusion · Memory suppression · Cognitive impairment · Synchronicity · Thought loops · Language suppression · Focus suppression · Information processing suppression · Memory fragmentation · Analysis enhancement · Creativity enhancement · Humor enhancement · Thought acceleration · Thought deceleration · Cognitive fatigue · Memory replays · Motivation enhancement · Information processing enhancement · Analysis suppression · Cognitive dysphoria · Thought organization · Delusions · Amnesia · Delirium
Cognitive euphoria · Novelty enhancement · Pattern recognition enhancement · Aesthetic enhancement · Cognitive flexibility · Thought disorganization · Increased nature relatedness · Confusion · Memory suppression · Cognitive impairment · Synchronicity · Thought loops · Language suppression · Focus suppression · Information processing suppression · Memory fragmentation · Analysis enhancement · Creativity enhancement · Humor enhancement · Thought acceleration · Thought deceleration · Cognitive fatigue · Memory replays · Motivation enhancement · Information processing enhancement · Analysis suppression · Cognitive dysphoria · Thought organization · Amnesia · Delirium
Catharsis · Euphoria · Anxiety · Anxiety suppression · Dysphoria · Irritability
Dysphoria · Irritability
Depersonalization · Compulsive behavior reduction · Disinhibition · Automaticity · Communication suppression · Sociability enhancement · Sociability suppression · Social disconnection · Communication enhancement · Flow state · Ego inflation · Boundary dissolution · Identity alteration · Ego dissolution · Cognitive disconnection · Telepathic feelings
Communication suppression · Sociability enhancement · Sociability suppression · Social disconnection · Communication enhancement · Flow state · Ego inflation · Boundary dissolution · Identity alteration · Ego dissolution · Cognitive disconnection · Telepathic feelings
Time cessation
Transpersonal visions · Death-rebirth sequence · Transpersonal memory access · Voidness · Entity contact · Cessation · Near-death experience
Entity contact · Cessation · Near-death experience
Lucidity enhancement · Recursive awareness
Timeline
First alerts emerge 20–45 minutes after ingestion: subtle mood shift, mild body tingling, slight visual brightening. Nausea may begin.
Effects intensify progressively over 45–90 minutes. Visual distortions emerge, body load increases, emotional sensitivity heightens. Anxiety at onset is common and typically transient.
Maximum intensity sustained for 1–2 hours. Full visual phenomena, ego dissolution potential, profound emotional and cognitive effects. Cardiovascular parameters at maximum elevation.
Intensity gradually diminishes while core perceptual and emotional effects remain. Cognitive clarity begins returning. Insights and emotional processing continue.
Effects progressively fade over 45–90 minutes. Visual phenomena resolve, normal thought patterns re-emerge. Fatigue and emotional tenderness are common.
Residual mood elevation, enhanced emotional openness, mild perceptual sensitivity, and reflective disposition may persist for 4–24 hours. Delayed headache may occur the following day.
⚠ Do not drive or operate heavy machinery for the remainder of the day following psilocin ingestion, as subtle cognitive and perceptual effects may persist beyond the apparent resolution of acute effects.
Safety[edit]
- Acute toxicity
- Negligible
- Chronic toxicity
- Negligible
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- LSD · mesc · DMT
Toxicity
Acute toxicity
Psilocin has an exceptionally wide safety margin. The lethal dose in animals is roughly a thousand times higher than a psychoactive human dose.[6] No human death from psilocin overdose alone has been reported in the medical literature.
Heart and circulation
Psilocin temporarily raises blood pressure — approximately +19 mmHg systolic and +9 mmHg diastolic across clinical dose ranges.[24] Heart rate does not significantly change. This warrants caution for people with pre-existing heart or blood pressure conditions.
Adverse effects in clinical trials
In the largest controlled trial to date (233 participants), 77% experienced side effects — predominantly headache, nausea, and dizziness.[11] Delayed headaches the day after are common and dose-dependent.[25] Across more than 1,000 clinical administrations in 30 studies, a meta-analysis found 9 serious adverse events total, with no suicide attempts during acute sessions.[26]
Psychological risks
Psychosis exacerbation
Psilocin can trigger or worsen psychotic symptoms in people with a personal or family history of psychotic disorders. This is the primary reason such individuals are excluded from clinical trials.[27]
Hallucinogen persisting perception disorder
Some people experience recurring visual disturbances after psilocin use — geometry, halos, after-images, and visual haze / noise that persist after the drug has cleared.[28] Incidence in clinical settings appears very low, though no precise rate for psilocin has been published.
Challenging experiences
In a US survey of 613 psychedelic users, 8.9% reported functional impairment lasting more than a day, and 2.6% sought professional help.[5] Six modifiable risk factors were identified: negative mindset, lack of preparation, absence of psychological support, unfavorable setting, excessive dose, and concurrent major life stress.
Suicidal ideation
In the COMPASS trial, suicidal thoughts occurred across all dose groups including the control, suggesting this reflects underlying depression rather than the drug itself.[11] No completed suicides have been reported in any published psilocybin trial.
Tolerance & dependence
Psilocin produces no physical dependence and no withdrawal. Tolerance builds rapidly through downregulation — noticeably after a single dose, near-complete within 3 days, fully reset by approximately 7 days.[7]
Complete cross-tolerance exists between psilocin, LSD, and mescaline.[29][30] A comprehensive analysis concluded psilocin shows marginal reinforcing properties, no compulsive use pattern, and substantially lower abuse potential than most Schedule I substances.[27]
Drug interactions
Lithium and mood stabilizers
SSRIs
Contrary to the common belief that SSRIs blunt the psychedelic experience, controlled data are more nuanced. Escitalopram pretreatment reduced anxiety, cardiovascular stress, and negative reactions without diminishing positive mood effects.[19] Psilocybin in patients on concurrent SSRIs still produced meaningful antidepressant improvements with no serious adverse events.[31]
5-HT₂A antagonists
Serotonin-receptor blockers — including antipsychotics such as risperidone, olanzapine, and quetiapine — can terminate or substantially reduce the psychedelic experience.[1][13] This makes them relevant as an emergency intervention and for patients on antipsychotic maintenance therapy.
MAO inhibitors
Contraindications
Psychiatric
Personal or family history of schizophrenia, bipolar disorder type I, schizoaffective disorder, or any psychotic disorder is an absolute contraindication.[27]
Pharmacological
Concurrent lithium or mood stabilizer use is an absolute contraindication based on epidemiological evidence of significantly increased harm.[5] MAOI co-administration is a relative contraindication based on metabolic pathway data.[20]safety citation needed
Cardiovascular
Uncontrolled high blood pressure or significant heart disease is a relative contraindication given documented blood pressure elevations.[24]
Other
Pregnancy and breastfeeding (insufficient safety data). No age-specific contraindications exist beyond standard clinical trial exclusion of minors.
Harm Reduction[edit]
Forms & Identification
Psilocin itself is almost never sold in isolated form. Real-world use involves dried Psilocybe mushrooms, fresh mushrooms, edibles such as chocolates or gummies, or synthetic psilocybin capsules. Potency varies significantly between species, individual specimens, and even parts of the same mushroom.
This natural variability makes precise dosing from raw fungal material difficult. Synthetic capsules and standardized extracts are more consistent, but mislabeled and adulterated products circulate in unregulated markets.
Guidelines
- Test material with a reagent kit to confirm identity before use
- Start with a low dose when using an unfamiliar batch or species — natural potency variation is substantial
- Eat lightly 2–3 hours beforehand to reduce nausea without delaying onset excessively
- Clear the schedule for the full day — effects last 4–6 hours, with residual shifts in mood and energy for several hours afterward
- Prepare the physical space in advance: comfortable seating, access to water, calming music, reduced stimulation
- Have a sober sitter present, especially at moderate-to-high doses
- Avoid redosing during the come-up — onset can take up to 90 minutes, and premature redosing risks an unexpectedly intense experience
- Write down an intention beforehand, however simple — this anchors the experience and supports integration afterward
Set & Setting
Psilocin's effects are unusually sensitive to psychological and environmental context. A calm, familiar space significantly reduces the likelihood of a difficult experience. Emotional state at ingestion matters: unresolved anxiety or grief can amplify into overwhelming intensity.
A trusted, sober companion — a "sitter" — is the single most protective factor for difficult experiences. Clinical training is not required. Quiet presence and refraining from imposing interpretation are more helpful than active intervention.
Aftercare & integration. The days following a psilocin experience often carry residual emotional openness. This window is valuable for processing what emerged during the experience, but can leave someone feeling vulnerable if the session was challenging.
- Write or record reflections within 24 hours, while impressions remain vivid
- Discuss the experience with a trusted person — a friend, therapist, or integration circle
- Avoid major life decisions in the first week; emotional clarity takes time to settle
- If distressing thoughts, perceptual changes, or mood instability persist beyond a few days, consult a mental health professional experienced with psychedelic integration
Recovery & Support
Psilocin does not produce physical dependence or withdrawal, and compulsive use patterns are rare. When problematic use does occur, it typically reflects an attempt to manage underlying psychological distress rather than pharmacological compulsion.
For those concerned about their pattern of use, harm reduction organizations such as the Fireside Project (62-FIRESIDE / 623-473-7433) and MAPS provide non-judgmental support. If psilocin experiences have contributed to lasting psychological distress, HPPD symptoms, or difficulty functioning, professional evaluation is warranted.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency
Most difficult psilocin experiences are psychologically distressing but not medically dangerous. Genuine emergencies include: expression of intent to harm oneself or others, complete disconnection from reality with dangerous behavior, seizures, or loss of consciousness. Severe chest pain or difficulty breathing warrants immediate medical attention.
Immediate steps
- Move the person to a quiet, safe space if possible
- Speak calmly and simply — "You took a psychedelic. This will end. You are safe."
- Do not restrain unless there is immediate risk of harm to self or others
- Do not leave the person alone
- If symptoms include seizure, loss of consciousness, or severe chest pain, call emergency services immediately
What to tell the dispatcher
State the substance (psilocybin mushrooms or psilocin), approximate amount, time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug-related emergency.
Legal Status[edit]
Psilocin is internationally controlled under the 1971 United Nations Convention on Psychotropic Substances, requiring most countries to restrict its manufacture, trade, and possession. Most jurisdictions classify psilocin and psilocybin identically as prohibited substances. Since 2023, two jurisdictions have created medical or supervised access pathways.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States (federal) | Schedule I (Controlled Substances Act, 1970) | No accepted medical use under federal law; psilocybin has received FDA Breakthrough Therapy Designation for MDD and TRD |
| Oregon (US state) | Supervised therapeutic use permitted | Measure 109 (operational January 2023): adults 21+ may access psilocybin through licensed service centers; possession outside centers remains illegal[12] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Maximum penalty for possession: 7 years; for supply: life imprisonment |
| Canada | Schedule III (CDSA) | Individual exemptions granted under Section 56 for therapeutic and end-of-life use since 2020 |
| Australia | Schedule 8 (TGA, effective July 1, 2023) | First Western country to permit medical prescription; authorized for TRD by authorized psychiatrists only[4] |
| European Union | Varies by member state (most: prohibited) | Based on UN 1971 Convention; Netherlands permits fresh truffles (containing psilocybin) through regulatory distinction |
| Japan | Prohibited (Narcotics and Psychotropics Control Law, 2002) | Psilocin and psilocybin-containing fungi specifically scheduled |
Analog and prodrug considerations
Psilocybin converts to psilocin in the body and is controlled identically in all jurisdictions. Synthetic 4-substituted tryptamine analogs (4-AcO-DMT, 4-HO-MET) may fall under analog legislation in jurisdictions with structural similarity provisions — notably the US Federal Analogue Act.
references
- [1] ^abcdKometer M, Schmidt A, Jaencke L, Vollenweider FX (2013) Activation of serotonin 2A receptors underlies the psilocybin-induced effects on alpha oscillations, N170 visual-evoked potentials, and visual hallucinations — Journal of Neuroscience doi:10.1523/jneurosci.3007-12.2013
- [2] ^abHofmann A, Troxler F (1959) Identifizierung von Psilocin (Identification of Psilocin) — Experientia doi:10.1007/bf02166696
- [3] ^abGriffiths RR, Richards WA, McCann U, Jesse R (2006) Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance — Psychopharmacology PMID:16826400
- [4]
- [5]
- [6] ^abZhuk O, Jasicka-Misiak I, Poliwoda A, Kazakova A, Godovan VV, Halama M, Wieczorek PP (2015) Research on acute toxicity and the behavioral effects of methanolic extract from psilocybin mushrooms and psilocin in mice — Toxins doi:10.3390/toxins7041018