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4-AcO-DET
4-acetoxy-N,N-diethyltryptamine
4-AcO-DET (4-acetoxy-N,N-diethyltryptamine) — also known as ethacetin — is a synthetic psychedelic of the tryptamine class. It is a prodrug structural analog of psilocybin, converted by the body into 4-HO-DET, the active compound.[1] That active compound activates serotonin receptors in the brain, producing the visual and introspective shifts characteristic of classical psychedelics.
4-AcO-DET (4-acetoxy-N,N-diethyltryptamine) — ethacetin — is a synthetic psychedelic of the tryptamine class. It is a prodrug structural analog of psilocybin, distinguished by its diethyl substitution and shorter duration. 4-AcO-DET is a presumed 5-HT₂A receptor agonist, producing its effects through its active metabolite 4-HO-DET after enzymatic hydrolysis.[1]
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Synthesized by Albert Hofmann at Sandoz Laboratories in 1958,[2] it was part of a systematic search for short-acting alternatives to psilocybin for clinical therapy. Its active metabolite, CZ-74, was used in psycholytic therapy across roughly 30 European clinical centers during the 1960s,[3] before the broader shutdown of psychedelic research. 4-AcO-DET itself appeared on the research chemical market in 2001 and remains unscheduled in most countries.[4]
Subjective effects include brightened colors, geometry, emotional intensification, time alteration, and ego dissolution. The experience is qualitatively similar to psilocybin but shorter — an emotionally vivid, introspective tryptamine state with strong visual and philosophical dimensions. Nausea, anxiety, thought loops, and confusion are common unwanted effects.
4-AcO-DET is not habit-forming and produces no physical dependence.[5] The primary danger is psychological — panic and potential triggering of psychotic episodes in predisposed individuals — compounded by combining with serotonin-raising drugs like MAOIs and tramadol, which can cause dangerous overheating. No controlled human studies exist for this compound; safety information is inferred from structural analogs.[1]
History[edit]
Discovery
4-AcO-DET was synthesized in 1958 by Albert Hofmann at Sandoz Laboratories in Basel,[2] as part of a systematic exploration of psilocybin-related tryptamine esters. Hofmann and Franz Troxler also synthesized the active metabolite 4-HO-DET (ethocin/CZ-74) and a phosphorylated structural analog, CEY-19[6] — both intended as shorter-acting alternatives to psilocybin for clinical use.
Clinical use
CZ-74 entered psycholytic therapy — the European model of psychedelic-assisted psychotherapy — during the 1960s.[3] Hanscarl Leuner deployed it across approximately 30 treatment centers; clinical reports described CZ-74 as producing virtually no side-effects at therapeutic doses.[7] Alexander and Ann Shulgin later documented both 4-HO-DET and its acetate ester in TiHKAL (1997), noting faster onset and greater potency than a simple prodrug would explain.[8]
Modern era
4-AcO-DET appeared on the research chemical market in May 2001, sold as ethacetin or ethylacybin.[4] Its parent compound DET is Schedule I under both the UN 1971 Convention and US federal law,[9] but 4-AcO-DET remains unscheduled in most countries. A 2022 DEA proposal to schedule related tryptamines was ultimately withdrawn,[10] though regulatory attention to this structural class continues.
The compound circulates under several names reflecting its synthetic lineage. Ethacetin derives from the N,N-diethyl substitution and acetoxy group; ethylacybin follows the pattern of "psilocybin" applied to the ethyl series. The Sandoz laboratory codes — CZ-74 for 4-HO-DET and CEY-19 for the phosphorylated analog — persist in pharmacological literature and occasionally surface in research chemical marketing, lending the compound an air of mid-century clinical legitimacy that belies its total absence of formal study.
Chemistry[edit]
Structural class
4-AcO-DET belongs to the 4-substituted tryptamine family, which includes psilocybin, psilocin, and 4-AcO-DMT. The acetoxy group at the 4-position of the indole ring makes it a prodrug: the body strips the acetate group to yield 4-HO-DET (CZ-74), the pharmacologically active form.[1] The N,N-diethyl substitution places it between the smaller dimethyl group of psilocin and larger diisopropyl variants in terms of molecular bulk.[11]
Molecular properties
The molecular formula is C₁₆H₂₂N₂O₂ (274.36 g/mol).[12] In freebase form, the compound is chemically unstable, degrading on exposure to air, light, and moisture.[4] Degraded samples contain 4-HO-DET plus two unidentified compounds of unknown toxicity.[4] Salt form and airtight frozen storage with desiccant may extend shelf life.[4]
Pharmacology[edit]
Mechanism of action
4-AcO-DET is believed to act as a prodrug.[4][1] Enzymes in the blood break it down into 4-HO-DET (CZ-74), the pharmacologically active compound — the same conversion observed in degraded samples.[4] This mirrors how psilocybin converts into psilocin.
4-HO-DET activates serotonin receptors — the primary target of all tryptamine psychedelics. No binding data specific to this compound have been published,safety citation needed but class-level research confirms strong serotonin receptor affinity for 4-substituted tryptamines.[11][13] Shulgin observed faster onset and greater potency than prodrug conversion alone would predict,[8] suggesting the intact compound may also act directly on receptors.
Pharmacokinetics
No human pharmacokinetic data exist for 4-AcO-DET.safety citation needed The active metabolite 4-HO-DET is expected to be broken down by liver enzymes, with monoamine oxidase playing a secondary role — by analogy to Psilocin.[14] Acetoxy prodrugs may activate more slowly or incompletely than phosphate ester prodrugs like psilocybin.[1]
Neuroscience[edit]
Where it acts
As a serotonin receptor activator (via its metabolite 4-HO-DET), 4-AcO-DET is expected to act on the same brain circuits documented for other serotonergic psychedelics. No neuroimaging data exist for this compound. In studies of psilocybin and LSD, serotonin receptor activation disrupts the brain's default mode network — the system that maintains the ongoing sense of self — while increasing communication between regions that normally work in isolation.
This disruption produces greater complexity in neural signaling and weakens the brain's filtering of sensory input. Visual distortions arise from disrupted sensory gating, altered self-perception from default mode dissolution, and novel thought patterns from increased cross-network connectivity.
Why it matters
The leading theoretical framework proposes that psychedelics reduce the brain's confidence in its existing models of reality, allowing raw sensory and emotional input to carry greater weight.citation needed Separately, serotonergic psychedelics may promote new neural connections through signaling cascades involving growth factor receptors.[15] Whether 4-AcO-DET engages these neuroplasticity pathways with meaningful potency is unknown.
Several fundamental questions about 4-AcO-DET remain unanswered. Does the intact compound activate serotonin receptors directly before hydrolysis, as Shulgin's observations suggested[8]? What are the identities and biological effects of the uncharacterized degradation products found in aged samples[4]? And does the diethyl substitution produce clinically meaningful differences in brain metabolism compared to psilocin's dimethyl group?
Subjective Effects[edit]
4-AcO-DET produces a tryptamine psychedelic experience with strong visual and emotional dimensions. Context shapes the character profoundly: in calm, familiar surroundings the experience tends toward introspection and aesthetic richness; in stressful settings, anxiety and thought loops are more likely. All effect reports derive from clinical experience with its active metabolite CZ-74[3] and community accounts.
The experience is qualitatively similar to psilocybin but shorter — an attribute that made its metabolite attractive for structured psycholytic therapy sessions in the 1960s.[8] Compared to 4-AcO-DMT, subtle qualitative differences from the diethyl substitution are reported, though no direct comparisons exist.
Synthesized by Albert Hofmann at Sandoz Laboratories in 1958 as part of systematic exploration of psilocybin-related tryptamine esters,[2] the compound itself received no formal study, though its active metabolite CZ-74 was employed in European psycholytic therapy during the 1960s.[3] It appeared on the research chemical market in 2001[4] and remains unscheduled in most jurisdictions.
Subjective effects include geometric visual patterns, emotional intensification, time alteration, and ego dissolution. The experience is reported as qualitatively similar to psilocybin but compressed in duration — a contained, emotionally vivid tryptamine state with prominent visual and introspective dimensions. Nausea, anxiety, thought loops, and depersonalization are common unsought effects.
4-AcO-DET is not considered habit-forming; rapid tolerance develops after a single dose via downregulation, making compulsive use self-limiting.[5] The primary risk is psychological — anxiety, panic, and potential precipitation of psychotic episodes in predisposed individuals — compounded by serotonergic drug interactions, particularly with MAOIs and tramadol. No controlled human studies, toxicity data, or binding profiles have been published for this compound; nearly all safety information is inferred from structural analogs.[1]
History[edit]
Discovery
4-AcO-DET was synthesized in 1958 by Albert Hofmann at Sandoz Laboratories in Basel, Switzerland,[2] as part of a systematic program exploring 4-substituted tryptamine esters following the isolation of psilocybin and psilocin. The parent scaffold, N,N-diethyltryptamine (DET), had been first synthesized by Stephen Szára and reported in 1957. Hofmann and Franz Troxler also synthesized the pharmacologically active metabolite 4-HO-DET (ethocin) under the laboratory code CZ-74, alongside a phosphorylated structural analog CEY-19[6] — both conceived as short-acting alternatives to psilocybin for clinical settings.
Clinical use
CZ-74 entered human use during the 1960s within the framework of psycholytic therapy, the European model of psychedelic-assisted psychotherapy.[3] Hanscarl Leuner of the University of Göttingen deployed CZ-74 and CEY-19 across approximately 30 treatment centers in Europe; clinical reports described CZ-74 as producing "virtually no side-effects" at therapeutic doses.[7] Alexander and Ann Shulgin later documented both 4-HO-DET and its acetate ester in TiHKAL (1997), noting that the ester appeared to show faster onset and increased potency beyond what simple prodrug conversion would predict.[8]
Modern era
4-AcO-DET first appeared on the research chemical market in May 2001, sold as "ethacetin" or "ethylacybin".[4] No formal clinical trials have been registered for the compound. Its parent scaffold DET is Schedule I under both the UN 1971 Convention on Psychotropic Substances and the U.S. DEA,[9] but 4-AcO-DET itself remains unscheduled in most countries — a legal grey zone that has drawn increasing regulatory attention, including a withdrawn 2022 DEA proposal targeting related tryptamines.[10]
The compound circulates under several names reflecting its synthetic lineage. Ethacetin derives from the N,N-diethyl substitution and acetoxy group; ethylacybin follows the pattern of "psilocybin" applied to the ethyl series. The Sandoz laboratory codes — CZ-74 for 4-HO-DET and CEY-19 for the phosphorylated analog — persist in pharmacological literature and occasionally surface in research chemical marketing, lending the compound an air of mid-century clinical legitimacy that belies its total absence of formal study.
Chemistry[edit]
Structural class
4-AcO-DET belongs to the 4-substituted tryptamine family, a class of indolealkylamine psychedelics that includes psilocybin, psilocin, and 4-AcO-DMT. The core structure is N,N-diethyltryptamine (DET) with a 4-acetoxy group (–OC(O)CH₃) attached at the indole 4-position. This acetoxy moiety makes 4-AcO-DET a structural ester prodrug: enzymatic hydrolysis cleaves the acetate group to yield 4-HO-DET (ethocin/CZ-74), the active 4-hydroxytryptamine.[1]
The N,N-diethyl substitution on the terminal amine distinguishes 4-AcO-DET from 4-AcO-DMT (N,N-dimethyl) and 4-AcO-MiPT (N-methyl-N-isopropyl). This places it in the middle range of N,N-dialkyl bulk among 4-substituted tryptamines — smaller than the diisopropyl group, which retains substantial serotonin receptor affinity,[11] but larger than the dimethyl group found in the psilocin series.
Molecular properties
| Molecular formula | C₁₆H₂₂N₂O₂ |
| Molecular weight | 274.36 g/mol |
The indole ring bears the acetoxy group at C-4 and a 2-(diethylamino)ethyl chain at C-3. At 274.36 g/mol, the compound exceeds its active metabolite 4-HO-DET (232.32 g/mol) by the mass of the acetyl moiety — meaning an equivalent weight of 4-AcO-DET delivers roughly 85% of the molar amount of active 4-HO-DET.[12]
Stereochemistry
4-AcO-DET contains no chirality centers. The compound exists as a single achiral species and requires no stereo-specific designation.
Stability
In freebase form, 4-AcO-DET presents as a tan powder that is chemically unstable, degrading upon exposure to air, light, and moisture.[4] Over months, material progresses from tan powder to a black tarry substance. Analysis of degraded samples identified 4-HO-DET as the primary breakdown product, along with two unidentified compounds of unknown pharmacological activity.[4]
The degradation mechanism appears to involve polymerization rather than simple oxidation. Degraded samples may retain significant potency, but the presence of uncharacterized breakdown products introduces unknown risk. Conversion to a salt form and storage in airtight, frozen, dark conditions with desiccant may improve stability.[4]
Pharmacology[edit]
Mechanism of action
4-AcO-DET is a presumed prodrug that undergoes hydrolysis by serum esterases to yield 4-HO-DET (ethocin/CZ-74), the pharmacologically active compound.[4][1] This parallels the psilocybin → psilocin conversion. Analysis of degraded 4-AcO-DET samples confirmed 4-HO-DET as the primary product, supporting the prodrug hypothesis.[4]
The active metabolite 4-HO-DET acts primarily as a 5-HT₂A receptor agonist — the principal mechanism shared by tryptamine psychedelics. No binding data specific to 4-AcO-DET or 4-HO-DET have been published.safety citation needed Class-level data for 4-substituted tryptamines indicate strong 5-HT₂A affinity with high selectivity over other serotonin receptor subtypes.[11][13]
Raithatha et al. (2024) found that 4-acetoxy tryptamines show somewhat weaker binding than their 4-hydroxy counterparts but retain similar target profiles across serotonin receptors.[1] Shulgin noted that 4-AcO-DET may possess independent activity beyond prodrug conversion, based on faster onset and greater potency than expected from hydrolysis alone.[8]
Pharmacokinetics
No human pharmacokinetic data have been published for 4-AcO-DET.safety citation needed The compound is believed to undergo rapid hydrolysis to 4-HO-DET via serum esterases, though the rate in humans is unknown. Raithatha et al. (2024) found that 4-acetoxy prodrugs demonstrated reduced pharmacological exposure compared with psilocybin, suggesting slower or less complete activation than phosphate ester prodrugs.[1]
By analogy to Psilocin, the active metabolite 4-HO-DET is expected to be broken down by liver enzymes with secondary contribution from MAO-A (MAO-A).[14] Studies of psilocin in humans report an half-life of 1.5–4 hours, time to peak blood levels of 1.8–4 hours after oral dosing, and bioavailability of approximately 53%.[14] Whether the larger N,N-diethyl group of 4-HO-DET meaningfully alters these parameters is unknown.
Neuroscience[edit]
Where it acts
As a serotonin 2A receptor agonist (via its metabolite 4-HO-DET), 4-AcO-DET is expected to act on the same brain circuits documented for other serotonergic psychedelics. No neuroimaging data exist for this compound. In studies of psilocybin and LSD, 5-HT₂A activation on cortical neurons disrupts the default mode network — the brain's self-referential processing system — while increasing communication between normally segregated brain regions.
This results in greater neural signal complexity and weakened sensory filtering, which maps onto the subjective experience: visual distortions arise from disrupted sensory gating, altered self-perception from default mode dissolution, and novel thought patterns from increased cross-network connectivity.
Why it matters
The leading theoretical framework, REBUS (Relaxed Beliefs Under Psychedelics), proposes that these compounds reduce the brain's confidence in its existing models of reality, allowing raw sensory and emotional input greater influence on conscious experience.citation needed Separately, serotonergic psychedelics may promote structural brain changes — new neural connections and strengthened synapses — through signaling cascades involving neurotrophin receptors.[15] Whether 4-AcO-DET engages these neuroplasticity pathways with meaningful potency is unknown.
Several fundamental questions about 4-AcO-DET remain unanswered. Does the intact compound activate 5-HT₂A receptors directly before hydrolysis, as Shulgin's observations suggested[8]? What are the identities and biological effects of the uncharacterized degradation products found in aged samples[4]? And does the diethyl substitution produce clinically meaningful differences in brain metabolism compared to psilocin's dimethyl group?
Subjective Effects[edit]
4-AcO-DET produces a tryptamine psychedelic experience with prominent visual and emotional dimensions, notably sensitive to set and setting. In supportive environments, the experience tends toward introspection and aesthetic richness; in stressful contexts, anxiety and thought loops become more likely. At lower doses, perceptual shifts and mood elevation dominate; at higher doses, the experience deepens into ego dissolution and transpersonal states. No controlled human studies have characterized its effects — all reports derive from clinical experience with its active metabolite CZ-74[3] and community accounts.
Relative to psilocybin, 4-AcO-DET is reported as qualitatively similar but shorter — an attribute that made its metabolite CZ-74 attractive for structured psycholytic therapy sessions in the 1960s.[8] Compared to 4-AcO-DMT, the diethyl substitution may produce subtle qualitative differences, though no direct comparisons exist.
Effect Grid
At common doses (15–20 mg oral), the full psychedelic experience emerges. Visual effects become pronounced: color alteration and enhancement, symmetrical texture repetition, visual drifting of surfaces and objects, depth perception distortion, and internal hallucinations with eyes closed. Tracers and after-images appear behind moving objects. Time distortion becomes significant — minutes may feel stretched or compressed.
Emotional enhancement is marked, with music, art, and interpersonal interactions taking on heightened significance. Thought connectivity and conceptual thinking increase substantially. Personal insight and immersion enhancement are commonly reported. Thought loops may occur at the upper end of this range.
Physically, nausea during onset is common, along with bruxism, muscle tension, bodily pressures, and temperature dysregulation. Appetite is fully suppressed. Increased urination and watery eyes may occur. Sleep is not possible for 5–7 hours after ingestion.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Visual drifting · Brightness alteration · Visual breathing · Depth perception distortion · Perspective distortion · Symmetrical texture repetition · Tracers · Environmental patterning · Light sensitivity · Visual morphing · After-images · Visual diffraction · Auditory distortion · Auditory enhancement · Peripheral vision distortion · Sound sensitivity · Touch enhancement · Visual haze / noise · Visual melting · Auditory misinterpretation · Peripheral misidentification · Proprioceptive distortion · Sleep-transition hallucinations · Spatial disorientation · Vestibular distortion · Holotropic state · Visual acuity enhancement · Dreaming enhancement · Synesthesia · Visual processing acceleration · Tinnitus · Visual magnification · Olfactory enhancement · Object transformations · Internal hallucinations · Environmental orbism / cubism · External hallucinations · Object activation · Visual recursion · Auditory hallucinations · Perspective hallucinations
Perspective distortion · Symmetrical texture repetition · Tracers · Environmental patterning · Light sensitivity · Visual morphing · After-images · Visual diffraction · Auditory distortion · Auditory enhancement · Peripheral vision distortion · Sound sensitivity · Touch enhancement · Visual haze / noise · Visual melting · Auditory misinterpretation · Peripheral misidentification · Proprioceptive distortion · Sleep-transition hallucinations · Spatial disorientation · Vestibular distortion · Holotropic state · Visual acuity enhancement · Dreaming enhancement · Synesthesia · Visual processing acceleration · Tinnitus · Visual magnification · Olfactory enhancement · Object transformations · Internal hallucinations · Environmental orbism / cubism · External hallucinations · Object activation · Visual recursion · Auditory hallucinations · Perspective hallucinations
Spontaneous body sensations · Appetite suppression · Insomnia · Physical fatigue · Stimulation · Wakefulness · Nausea · Laughter fits · Tactile euphoria · Tingling / electric sensations · Bodily pressures · Dehydration sensation · Dizziness · Muscle tension · Vibrations / buzzing · Bodily heaviness · Bodily lightness · Body schema distortion · Breathing alteration · Dry mouth · Heart rate perception changes · Sedation · Watery eyes · Increased urination · Headache · Restlessness · Excessive sweating · Muscle relaxation · Sexual arousal enhancement · Yawning · Nasal congestion · Abnormal heartbeat · Bruxism · Diarrhea · Involuntary body movements · Nystagmus (eye wobbles) · Respiratory stimulation · Salivation · Trembling · Vomiting · Bodily dissociation · Tactile hallucination
Physical fatigue · Stimulation · Wakefulness · Nausea · Laughter fits · Tactile euphoria · Tingling / electric sensations · Bodily pressures · Dehydration sensation · Dizziness · Muscle tension · Vibrations / buzzing · Bodily heaviness · Bodily lightness · Body schema distortion · Breathing alteration · Dry mouth · Heart rate perception changes · Sedation · Watery eyes · Increased urination · Headache · Restlessness · Excessive sweating · Muscle relaxation · Sexual arousal enhancement · Yawning · Nasal congestion · Bruxism · Diarrhea · Involuntary body movements · Nystagmus (eye wobbles) · Respiratory stimulation · Salivation · Trembling · Vomiting · Bodily dissociation · Tactile hallucination
Introspection enhancement · Openness enhancement · Conceptual thinking · Immersion enhancement · Novelty enhancement · Cognitive euphoria · Cognitive flexibility · Cognitive impairment · Memory suppression · Focus suppression · Increased nature relatedness · Multiple thought streams · Creativity enhancement · Humor enhancement · Thought loops · Analysis enhancement · Cognitive fatigue · Confusion · Information processing suppression · Memory fragmentation · Synchronicity · Thought acceleration · Thought disorganization · Analysis suppression · Language suppression · Motivation suppression · Thought deceleration · Information processing enhancement · Language enhancement · Motivation enhancement · Cognitive dysphoria · Memory replays · Focus enhancement · Memory enhancement · Delusions
Immersion enhancement · Novelty enhancement · Cognitive euphoria · Cognitive flexibility · Cognitive impairment · Memory suppression · Focus suppression · Increased nature relatedness · Multiple thought streams · Creativity enhancement · Humor enhancement · Thought loops · Analysis enhancement · Cognitive fatigue · Confusion · Information processing suppression · Memory fragmentation · Synchronicity · Thought acceleration · Thought disorganization · Analysis suppression · Language suppression · Motivation suppression · Thought deceleration · Information processing enhancement · Language enhancement · Motivation enhancement · Cognitive dysphoria · Memory replays · Focus enhancement · Memory enhancement
Empathy enhancement · Anxiety · Catharsis · Anxiety suppression · Dysphoria · Irritability
Dysphoria · Irritability
Depersonalization · Social connection · Trust enhancement · Communication enhancement · Flow state · Sociability enhancement · Automaticity · Communication suppression · Compulsive behavior reduction · Sociability suppression · Social disconnection · Ego inflation · Boundary dissolution · Identity alteration · Ego dissolution · Cognitive disconnection · Telepathic feelings
Flow state · Sociability enhancement · Automaticity · Communication suppression · Compulsive behavior reduction · Sociability suppression · Social disconnection · Ego inflation · Boundary dissolution · Identity alteration · Ego dissolution · Cognitive disconnection · Telepathic feelings
Time cessation
Non-dual awareness · Transpersonal memory access · Transpersonal visions · Cessation · Death-rebirth sequence · Voidness · Near-death experience
Death-rebirth sequence · Voidness · Near-death experience
Lucidity enhancement · Recursive awareness
Timeline
First alerts appear as a subtle shift in body awareness — mild warmth, slight visual brightening, and a sense that perception has shifted from baseline. Yawning is common during this phase.
Effects build steadily with increasing visual activity (color enhancement, early drifting), rising emotional sensitivity, and mounting body load. Nausea peaks during this phase and typically resolves before the peak. Mild anxiety or restlessness is common as intensity escalates.
Maximum intensity of visual, cognitive, and emotional effects. Visual distortions, internal hallucinations, time distortion, and thought connectivity are at their strongest. Emotional responses are profoundly intensified.
Effects gradually diminish. Visuals fade, cognitive clarity returns incrementally, and emotional intensity decreases. A sense of mental fatigue or spaciousness may alternate.
Residual mood elevation, mild perceptual sensitivity, and a sense of cognitive openness may persist for several hours. Sleep quality may be affected. Appetite returns gradually.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Low
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- psilo · psilocin · LSD
Toxicity
No lethal dose data exist for 4-AcO-DET in any species, and no case reports of overdose or death attributable to the compound have been published.[16][17] This absence likely reflects limited detection: tryptamines are not part of standard toxicology panels, so their contribution to drug-related emergencies may be significantly underestimated.[17]
Degradation product hazard
Aged material degrades to 4-HO-DET plus two unidentified compounds with unknown toxicity.[4] Discolored material may contain active or toxic components with unpredictable effects.
Psychological risks
Acute risks include anxiety, panic, paranoia, and dysphoria. At high doses, thought loops, ego dissolution, and depersonalization can become severely distressing.
Prolonged psychotic episodes have been documented in people with personal or family history of psychotic disorders or bipolar disorder using serotonergic psychedelics. Persistent visual disturbances after use — a condition known as HPPD — have been reported with tryptamine psychedelics, though reliable prevalence estimates do not exist. No published adverse event data specific to 4-AcO-DET exist.safety citation needed
Tolerance and dependence
4-AcO-DET is not habit-forming. Tolerance builds rapidly — even after a single dose — because serotonin receptors in the frontal cortex downregulate in response.[5] The same mechanism that reduces sensitivity also removes the drive to redose, making compulsive use pharmacologically self-limiting.
Tolerance is estimated to halve over roughly 3 days and fully reset at approximately 7 days. It extends to other serotonergic psychedelics including psilocybin, LSD, and DMT. Related tryptamines show low reinforcement and low abuse liability in animal studies.[18]
Drug Interactions
The main hazard is combining 4-AcO-DET with drugs that raise serotonin levels. The active metabolite 4-HO-DET acts on the serotonin system and may also affect the SERT,[19] creating multiple pathways for serotonin overload in combination.
Tramadol poses the most clearly documented danger. It blocks serotonin reuptake[20][21] and is among the opioids most associated with serotonin syndrome[20] — a potentially fatal overheating and seizure response. Case reports confirm severe, prolonged serotonin toxicity from this combination.[22][21]
MAOIs block the enzyme that breaks down 4-HO-DET, dramatically amplifying effects in dangerous and unpredictable ways.[14] SSRIs and SNRIs may alter or intensify effects, with serotonin syndrome risk at higher doses. Lithium has been linked to seizures and heart rhythm disturbances when combined with serotonergic psychedelics.safety citation needed Cannabis may intensify effects and raise anxiety through non-serotonin mechanisms.
Contraindications
7 knownNo substance-specific contraindication data exist for 4-AcO-DET. The following are inferred from serotonin receptor agonist pharmacology and class-level evidence.safety citation needed
Absolute contraindications:
- Personal or family history of psychotic disorders or schizophrenia — serotonin receptor activation may trigger or worsen psychotic episodes, the most consistently documented psychiatric risk across serotonergic psychedelics.
- Concurrent MAOI therapy — risk of dangerous and unpredictable serotonergic potentiation.
- Concurrent lithium therapy — seizure and heart rhythm disturbance risk documented for the psychedelic class.
Relative contraindications:
- Bipolar disorder — risk of triggering manic episodes.
- Concurrent SSRI/SNRI therapy — altered and unpredictable effects; serotonin syndrome risk at higher doses.
- Heart conditions — increased heart rate and blood pressure are reported for the serotonergic psychedelic class.
- Pregnancy and nursing — no safety data exist; serotonergic psychedelics are contraindicated due to unknown effects on fetal development.
Harm Reduction[edit]
Forms & Identification
4-AcO-DET circulates almost exclusively as a powder in freebase form. Color is a meaningful quality signal: fresh material is tan, while significantly darkened material contains unknown degradation products and carries unpredictable risk.[4]
A milligram-precision scale (0.001 g) is essential. Effective doses are measured in milligrams, and estimation errors at this scale can mean the difference between a light experience and an overwhelming one.
Guidelines
- Test all material with reagent kits before use. Verify substance identity — mislabeling and cross-contamination are real risks in unregulated markets.
- Use a milligram-precision scale. Never estimate doses by eye.
- Start at the low end of the dose range, particularly with new batches or unfamiliar sources. Individual sensitivity varies significantly.
- Eat lightly several hours beforehand to reduce nausea during onset.
- Prepare the physical space: comfortable temperature, accessible water, calming music, minimal stimulation available if needed.
- Keep a phone accessible with emergency contacts saved but set aside to avoid anxiety-inducing screen time.
- Avoid redosing during the experience — rapid tolerance means a second dose within hours will be substantially weaker and extends duration without proportional benefit.
Set & Setting
4-AcO-DET is highly sensitive to context. A calm, familiar environment with trusted companions substantially reduces the likelihood of anxiety and panic.
First experiences should take place somewhere that feels genuinely safe, with no obligations or social pressures for the full duration plus several hours of recovery. A sober, experienced companion who can provide reassurance without interference is strongly recommended, particularly at moderate-to-high doses where ego dissolution may occur.
Aftercare & integration. The day following a 4-AcO-DET experience often carries residual emotional sensitivity and mild fatigue. Allow a full day of low-demand activity for recovery. Journaling or discussing the experience with a trusted person within 24–48 hours can help process intense emotional or perceptual content.
If the experience was distressing, repeated intrusive thoughts or persistent mood changes lasting more than two weeks warrant professional support. Integration therapists specializing in psychedelic experiences can help contextualize difficult material. Persistent visual disturbances (HPPD) are rare but should be evaluated by a clinician if they occur.
Recovery & Support
4-AcO-DET does not produce physical dependence, and compulsive use patterns are rare due to rapid tolerance. However, psychological reliance on psychedelic experiences — using them to avoid addressing underlying emotional difficulties — can develop with any substance in this class. If psychedelic use is becoming a coping mechanism rather than an occasional experience, peer support communities and psychedelic-informed therapists can help re-establish healthier patterns.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Most difficult psychedelic experiences are psychologically distressing but not medically dangerous. An emergency exists when the individual shows signs of self-harm risk, complete disconnection from reality with dangerous behavior, seizures, severe chest pain, or sustained high fever.
Immediate steps:
- 1. Stay calm. Speak in a steady, quiet voice.
- 2. Move the individual to a safe, low-stimulation environment if possible.
- 3. Do not restrain unless there is immediate danger of self-harm or harm to others.
- 4. If seizures occur, the person is unresponsive, or symptoms suggest serotonin syndrome (rigid muscles, high fever, rapid heartbeat, agitation), call emergency services immediately.
- 5. While waiting for help, keep the person cool if overheating and place them in a recovery position if unconscious.
What to tell the dispatcher: Name the substance (4-AcO-DET, a tryptamine psychedelic), approximate amount taken, time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect callers from drug-related prosecution when seeking medical help.
Legal Status[edit]
4-AcO-DET occupies an ambiguous legal position in most jurisdictions — its parent compound DET is internationally controlled, but 4-AcO-DET itself is not separately listed in any international convention.[9]
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Not explicitly scheduled | DET is DEA Schedule I (code 7434).[9] 4-AcO-DET may be prosecuted under the Federal Analog Act (21 U.S.C. § 813) if intended for human consumption. The DEA's 2022 proposed rule targeting related tryptamines was withdrawn in July 2022.[10] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Controlled under the generic tryptamine catch-all clause. Additionally covered by the Psychoactive Substances Act 2016.[23] |
| Canada | Not explicitly listed (CDSA) | Not specifically listed under the Controlled Drugs and Substances Act as of 2025. Analog provisions may apply; legal status requires expert assessment.citation needed |
| Australia | Unconfirmed; likely Schedule 9 | Not explicitly confirmed in the TGA Poisons Standard. By analogy to psilocin esters, may be captured as a Schedule 9 prohibited substance.citation needed |
| International (UN) | DET is Schedule I; 4-AcO-DET not listed | DET is controlled under the 1971 Convention on Psychotropic Substances. 4-AcO-DET is not separately listed, leaving its status to national legislation.[9] |
Analog and prodrug considerations
The Federal Analog Act potentially captures 4-AcO-DET as a substantially similar compound to DET when intended for human consumption. Its dual status as both a structural analog of a scheduled substance and a prodrug for an unscheduled active tryptamine creates layered legal complexity. The DEA's 2022 proposed rule, though withdrawn, signals continued regulatory attention to this structural class.[10]
Legal status changes frequently and varies by jurisdiction. This is not legal advice. Verify current laws locally before making any decisions.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Low
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- psilo · psilocin · LSD
Toxicity
No lethal dose data have been published for 4-AcO-DET in any species. No animal toxicity studies specific to this compound were identified in tryptamine toxicology reviews.[16][17] No case reports of adverse events, overdose, or death attributable to 4-AcO-DET exist in the published literature.
This absence may reflect limited detection rather than genuine safety: tryptamines are not included in standard toxicology screening panels, and their contribution to drug-related emergencies may be significantly underestimated.[17]
Degradation product hazard
Aged 4-AcO-DET samples degrade to 4-HO-DET plus two unidentified compounds with unknown toxicity profiles.[4] The degradation involves polymerization, not simple oxidation. Discolored material may contain unpredictable active or toxic components.
Psychological risks
The psychedelic class risk profile applies to 4-AcO-DET by pharmacological inference. Acute psychological risks include anxiety, panic reactions, paranoia, and dysphoria. At high doses, thought loops, ego dissolution, and depersonalization may become severely distressing.
Prolonged psychotic episodes are documented for the serotonergic psychedelic class in individuals with personal or family history of psychotic disorders or bipolar disorder. Hallucinogen persisting perception disorder (HPPD) — persistent visual disturbances after psychedelic use — has been reported with tryptamine psychedelics, though reliable prevalence estimates do not exist. No published psychological adverse event data specific to 4-AcO-DET exist.safety citation needed
Tolerance and dependence
4-AcO-DET is not considered habit-forming. Tolerance develops rapidly after even a single dose, driven by 5-HT₂A downregulation in the frontal cortex.[5] This tolerance is pharmacologically self-limiting: the same mechanism that reduces sensitivity also removes the reinforcement that would drive repeated use.
Tolerance half-life is estimated at approximately 3 days, with full reset at approximately 7 days. Cross-tolerance extends to other serotonergic psychedelics including psilocybin, LSD, and DMT. Related substituted tryptamines show low reinforcing effects and low abuse liability in animal studies.[18]
Drug Interactions
The primary pharmacological hazard is additive serotonergic activity when 4-AcO-DET is combined with other drugs acting on the serotonin system. The active metabolite 4-HO-DET is a 5-HT₂A agonist that may also interact with the SERT,[19] creating multiple pathways for serotonin syndrome in combination.
Tramadol poses the most clearly documented danger. Tramadol blocks serotonin reuptake[20][21] and is among the opioids most associated with serotonin syndrome.[20] Case reports confirm severe and prolonged serotonin toxicity from tramadol combinations.[22][21]
MAOIs would dramatically potentiate effects by blocking MAO-A, a key enzyme in metabolizing the active compound 4-HO-DET.[14] This could produce unpredictable, prolonged, or dangerous serotonergic effects.
SSRIs and SNRIs may attenuate or unpredictably potentiate psychedelic effects. Risk of serotonin syndrome exists, particularly at higher SSRI/SNRI doses.
Lithium combined with serotonergic psychedelics has been associated with seizures and heart rhythm disturbances in case reports involving related tryptamines and lysergamides.safety citation needed
Cannabis may intensify subjective psychedelic effects and increase risk of anxiety and panic through mechanisms independent of the serotonin system.
Contraindications
7 knownNo substance-specific contraindication data exist for 4-AcO-DET. The following are inferred from the 5-HT₂A agonist mechanism and class-level evidence.safety citation needed
Absolute contraindications:
- Personal or family history of psychotic disorders or schizophrenia — 5-HT₂A agonism may trigger or worsen psychotic episodes, the most consistently documented psychiatric risk across serotonergic psychedelics.
- Concurrent MAOI therapy — risk of dangerous and unpredictable serotonergic potentiation.
- Concurrent lithium therapy — seizure and heart rhythm disturbance risk documented for the psychedelic class.
Relative contraindications:
- Bipolar disorder — risk of triggering manic episodes.
- Concurrent SSRI/SNRI therapy — altered and unpredictable effects; serotonin syndrome risk at higher doses.
- Heart conditions — increased heart rate and blood pressure are reported for the serotonergic psychedelic class.
- Pregnancy and nursing — no safety data exist; serotonergic psychedelics are contraindicated due to unknown effects on fetal development.
Harm Reduction[edit]
Forms & Identification
4-AcO-DET circulates almost exclusively as a powder, typically in freebase form. The freebase degrades visibly over time — fresh material is tan, while degraded material darkens progressively toward black.[4] Color alone is a meaningful signal: significantly darkened material contains unknown degradation products and carries unpredictable risk. A milligram-precision scale (0.001 g) is essential — effective doses are measured in milligrams, and estimation errors at this scale can mean the difference between a light and overwhelming experience.
Guidelines
- Test all material with reagent kits before use. Verify substance identity — mislabeling and cross-contamination are real risks in unregulated markets.
- Use a milligram-precision scale. Never estimate doses by eye.
- Start at the low end of the dose range, particularly with new batches or unfamiliar sources. Individual sensitivity varies significantly.
- Eat lightly several hours beforehand to reduce nausea during onset.
- Prepare the physical space: comfortable temperature, accessible water, calming music, minimal stimulation available if needed.
- Keep a phone accessible with emergency contacts saved but set aside to avoid anxiety-inducing screen time.
- Avoid redosing during the experience — rapid tolerance means a second dose within hours will be substantially weaker and extends duration without proportional benefit.
Set & Setting
4-AcO-DET is highly sensitive to context. A calm, familiar environment with trusted companions substantially reduces the likelihood of anxiety and panic. First experiences should take place somewhere the individual feels genuinely safe, with no obligations or social pressures for the full duration plus several hours of recovery. An experienced, sober companion who can provide reassurance without interference is strongly recommended, particularly at moderate-to-high doses where ego dissolution may occur.
Aftercare & integration. The day following a 4-AcO-DET experience often carries residual emotional sensitivity and mild fatigue. Allow a full day of low-demand activity for recovery. Journaling or discussing the experience with a trusted person within 24–48 hours can help process intense emotional or perceptual content.
If the experience was distressing, repeated intrusive thoughts or persistent mood changes lasting more than two weeks warrant professional support. Integration therapists specializing in psychedelic experiences can help contextualize difficult material. Persistent visual disturbances (HPPD) are rare but should be evaluated by a clinician if they occur.
Recovery & Support
4-AcO-DET does not produce physical dependence, and compulsive use patterns are rare due to rapid tolerance. However, psychological reliance on psychedelic experiences — using them to avoid addressing underlying emotional difficulties — can develop with any substance in this class. If psychedelic use is becoming a coping mechanism rather than an occasional experience, peer support communities and psychedelic-informed therapists can help re-establish healthier patterns.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Most difficult psychedelic experiences are psychologically distressing but not medically dangerous. An emergency exists when the individual shows signs of self-harm risk, complete disconnection from reality with dangerous behavior, seizures, severe chest pain, or sustained high fever.
Immediate steps:
- 1. Stay calm. Speak in a steady, quiet voice.
- 2. Move the individual to a safe, low-stimulation environment if possible.
- 3. Do not restrain unless there is immediate danger of self-harm or harm to others.
- 4. If seizures occur, the person is unresponsive, or symptoms suggest serotonin syndrome (rigid muscles, high fever, rapid heartbeat, agitation), call emergency services immediately.
- 5. While waiting for help, keep the person cool if overheating and place them in a recovery position if unconscious.
What to tell the dispatcher: Name the substance (4-AcO-DET, a tryptamine psychedelic), approximate amount taken, time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect callers from drug-related prosecution when seeking medical help.
Legal Status[edit]
4-AcO-DET occupies an ambiguous legal position in most jurisdictions. Its parent scaffold DET is internationally controlled under Schedule I of the United Nations 1971 Convention on Psychotropic Substances,[9] but 4-AcO-DET itself is not separately listed in any international convention. Several jurisdictions control it under generic tryptamine provisions or structural analog statutes, while others have not addressed it specifically.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Not explicitly scheduled | DET is DEA Schedule I (code 7434).[9] 4-AcO-DET may be prosecuted under the Federal Analog Act (21 U.S.C. § 813) if intended for human consumption. The DEA's 2022 proposed rule targeting related tryptamines was withdrawn in July 2022.[10] |
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Controlled under the generic tryptamine catch-all clause. Additionally covered by the Psychoactive Substances Act 2016.[23] |
| Canada | Not explicitly listed (CDSA) | Not specifically listed under the Controlled Drugs and Substances Act as of 2025. Analog provisions may apply; legal status requires expert assessment.citation needed |
| Australia | Unconfirmed; likely Schedule 9 | Not explicitly confirmed in the TGA Poisons Standard. By analogy to psilocin esters, may be captured as a Schedule 9 prohibited substance.citation needed |
| International (UN) | DET is Schedule I; 4-AcO-DET not listed | DET is controlled under the 1971 Convention on Psychotropic Substances. 4-AcO-DET is not separately listed, leaving its status to national legislation.[9] |
Analog and prodrug considerations
The Federal Analog Act potentially captures 4-AcO-DET as a "substantially similar" compound to DET (Schedule I) when intended for human consumption. The compound's dual status as both a structural analog of a scheduled substance and a prodrug for 4-HO-DET — an unscheduled but pharmacologically active tryptamine — creates layered legal complexity. The DEA's 2022 proposed rule, though withdrawn, signals continued regulatory attention to novel tryptamines in this structural class.
Frequently asked questions
What is 4-AcO-DET?
4-AcO-DET is a synthetic substituted tryptamine psychedelic and prodrug for 4-HO-DET, first synthesized by Albert Hofmann at Sandoz in 1958. Its active metabolite was used in European psycholytic therapy during the 1960s; no clinical trials of 4-AcO-DET itself have been conducted.
How long does 4-AcO-DET last?
Total duration by route of administration — Oral: 4 – 7 hours. Ranges vary with dose and individual factors; see the duration table for onset, peak, and after-effect phases.
Where can I find dosage information for 4-AcO-DET?
Psychedex publishes a dosage table for 4-AcO-DET on this page covering these routes of administration: oral. Dose values are presented only in that table, always alongside their route of administration.
What are dangerous combinations with 4-AcO-DET?
The highest-severity documented interactions for 4-AcO-DET: MAOIs (Lethal), Dopamine agonists (Dangerous), GHB, Baclofen (Dangerous), GHB, GBL (Dangerous), Ibogaine (Dangerous). See the interactions section for the full list with mechanisms and severity levels.
Is 4-AcO-DET addictive?
Psychedex records tolerance and dependence data rather than a yes/no rating. Recorded tolerance indicators for 4-AcO-DET: tolerance builds rapid; full reset takes 7 days; cross-tolerance develops with psilocybin, psilocin, LSD, DMT, mescaline, 4-AcO-DMT. See the article's dependence and safety sections for recorded dependence data.
experience reports
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First-person accounts of subjective effects, timing, and outcomes — submitted for harm reduction.
references
- [1]
- [2]
- [3] ^abcPassie T, Guss J, Krähenmann R (2022) Lower-Dose Psycholytic Therapy - A Neglected Approach — Frontiers in Psychiatry doi:10.3389/fpsyt.2022.1020505
- [4]
- [5] ^abde la Fuente Revenga M, Jaster AM, McGinn J, Silva G, Saha S, Gonzalez-Maeso J (2022) Tolerance and Cross-Tolerance among Psychedelic and Nonpsychedelic 5-HT2A Receptor Agonists in Mice — ACS Chemical Neuroscience doi:10.1021/acschemneuro.2c00170
- [6]
references
- [1]
- [2]
- [3] ^abcPassie T, Guss J, Krähenmann R (2022) Lower-Dose Psycholytic Therapy - A Neglected Approach — Frontiers in Psychiatry doi:10.3389/fpsyt.2022.1020505
- [4]
- [5] ^abde la Fuente Revenga M, Jaster AM, McGinn J, Silva G, Saha S, Gonzalez-Maeso J (2022) Tolerance and Cross-Tolerance among Psychedelic and Nonpsychedelic 5-HT2A Receptor Agonists in Mice — ACS Chemical Neuroscience doi:10.1021/acschemneuro.2c00170
- [6]