4-HO-DET
4-hydroxy-N,N-diethyltryptamine
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4-HO-DET (4-hydroxy-N,N-diethyltryptamine) — also known as CZ-74 — is a synthetic psychedelic of the tryptamine class. It is the diethyl counterpart of psilocin, the active compound in psilocybin mushrooms. It activates serotonin receptors in the brain, producing the visual and cognitive shifts characteristic of classical psychedelics.
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psilocybin, psilocin, LSD +5 morepsilocybin, psilocin, LSD, mescaline, DMT, 4-AcO-DMT, 4-HO-MET, 4-AcO-DET show less
Albert Hofmann and Franz Troxler synthesized it at Sandoz Pharmaceuticals in the late 1950s.[1] Hanscarl Leuner conducted over 160 psycholytic therapy sessions with it in 1960s Germany, valuing its shorter duration compared to LSD.[2] Clinical use ended with prohibition in the early 1970s; it now circulates in small quantities on research chemical markets.
Subjective effects include geometric visual patterns, emotional intensification, time alteration, and shifts in thought.[3] The experience is close to psilocin — warm, moderately paced, and emotionally saturating — with reports of a slightly lighter physical sensation.[4] Nausea, body tremors, and jaw tension are common unwanted effects.[5]
4-HO-DET does not produce physical dependence, and rapid tolerance limits compulsive use.[6][7] The primary risks are psychological — panic, paranoia, and psychosis in predisposed individuals — and combining it with MAOIs or tramadol risks dangerous overheating and seizures. No controlled safety data exist; what is known comes from Shulgin's personal bioassays and Leuner's unpublished clinical observations.[5]
History[edit]
Discovery
4-HO-DET was synthesized by Albert Hofmann and Franz Troxler at Sandoz Pharmaceuticals in Basel in the late 1950s, designated internally as CZ-74.[1] It emerged from Sandoz's systematic exploration of psychoactive tryptamines following Hofmann's isolation of psilocybin in 1958.[8] A phosphate ester prodrug — ethocybin (CEY-19) — was developed alongside it, mirroring the psilocybin-to-psilocin relationship.
Clinical significance
Hanscarl Leuner conducted more than 160 psycholytic therapy sessions using CZ-74 in 1960s Germany.[2][5] He valued it over LSD primarily for its shorter duration, which fit within a standard clinical workday. His unpublished German-language records remain the largest body of human clinical data for the compound.
Prohibition and modern use
International prohibition ended clinical use in the early 1970s. Alexander Shulgin documented the compound as entry #16 in his 1997 book TiHKAL, providing synthesis procedures, personal bioassays at 10–25 mg, and historical context that continues to inform community knowledge.[5] 4-HO-DET has appeared on research chemical markets since the 2000s, but no clinical trials have been initiated.
The laboratory designation CZ-74 originated from Sandoz's internal compound numbering system. The name ethocybin for the phosphate ester prodrug (CEY-19) was coined by analogy with psilocybin, reflecting the ethyl-for-methyl substitution pattern. Shulgin's TiHKAL entry established the reference dosage and subjective effect profile that circulates in online psychedelic communities, making it one of the earliest tryptamines documented outside institutional research.
Chemistry[edit]
Structural class
4-HO-DET belongs to the 4-substituted tryptamine family — the same structural group as psilocin and 4-HO-MET.[7] It differs from psilocin only at the nitrogen: two ethyl groups replace psilocin's two methyl groups. Its molecular formula is C₁₄H₂₀N₂O (232.32 g/mol), and it has no chirality centers.[9]
A related prodrug, ethocybin (CEY-19), carries a phosphate ester at the 4-position that must be stripped by enzymes before the compound becomes active — the same conversion pathway as psilocybin to psilocin.[7]
Pharmacology[edit]
Mechanism of action
4-HO-DET activates serotonin receptors — the same mechanism as psilocin and other classical psychedelics.[7][9] In animal studies, it fully substitutes for a known hallucinogen, confirming this activity in living systems.[4] At higher doses, additional serotonin pathways add sedation and temperature changes to the perceptual effects.[3][10] No binding measurements specific to 4-HO-DET exist; its pharmacology is inferred from structural analogy to psilocin.
Pharmacokinetics
No human pharmacokinetic data exist for 4-HO-DET. Psilocin — the closest studied structural analog — reaches peak blood levels within 2–4 hours after oral use and clears within 1.5–4 hours.[11][12] Because 4-HO-DET does not require prodrug conversion, it may act faster than psilocybin at equivalent doses, though this is unconfirmed.
Neuroscience[edit]
Where it acts
No neuroimaging studies have been conducted with 4-HO-DET. Based on its confirmed serotonin receptor activity,[4] it is expected to act on neurons in the prefrontal cortex that regulate perception and self-referential thought.[13][14] Disrupting these neurons — as seen with psilocybin and LSD — loosens ego boundaries and dissolves ordinary perceptual filters.[13]
Why it matters
One influential model proposes that serotonin agonists loosen entrenched mental patterns, letting the brain process information with fewer habitual constraints.[13] Psilocin also promotes new neural connections downstream of serotonin receptor activation.[14] Whether 4-HO-DET produces the same neuroplastic effects has not been measured.
Key unknowns include whether 4-HO-DET produces neuroplastic effects comparable to psilocin, whether its receptor residence time differs meaningfully from psilocin (potentially explaining subtle duration or qualitative differences), and whether the reported experiential differences between the two compounds reflect genuine pharmacological distinctions or artifacts of expectation and dose variability in uncontrolled settings.
Subjective Effects[edit]
4-HO-DET produces a warm, moderately paced psychedelic experience that responds strongly to context. Emotional tone, visual intensity, and depth of introspection all shift with psychological state and environment[3] — a calm space can anchor the experience, while an anxious one amplifies it. Material quality also matters: degraded compound produces attenuated, inconsistent effects.[5]
Within the 4-hydroxytryptamine series, 4-HO-DET sits closest to psilocin — similar potency, similar duration, similar emotional warmth.[4] Uncontrolled reports describe a marginally lighter body load and subtle differences in emotional coloring. Shulgin noted distinct textures between the free compound and its prodrug ethocybin, though this has not been confirmed in controlled studies.[5]
Effect Grid
At common doses (15–25 mg oral), the full psychedelic experience manifests: pronounced visual drifting and morphing of surfaces, geometric patterning in peripheral vision and with eyes closed, color enhancement, and depth perception alterations. Thought loops and heightened pattern recognition emerge. Emotional responses intensify significantly — personal insight and meaningful ideation are characteristic. Time distortion is prominent.
Physically, nausea or stomach discomfort may occur during onset. Jaw tension, body tremors, and temperature dysregulation become possible. Increased urination is reported. Pupil dilation is marked.
Functional impairment is significant at this range. The experience demands 5–6 hours of committed time, and residual effects may persist for several additional hours.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Visual breathing · Holotropic state · Depth perception distortion · Perspective distortion · Symmetrical texture repetition · Music enhancement · Tracers · Brightness alteration · Touch enhancement · After-images · Auditory enhancement · Environmental patterning · Light sensitivity · Sound sensitivity · Visual haze / noise · Visual morphing · Proprioceptive distortion · Auditory distortion · Auditory misinterpretation · Peripheral vision distortion · Spatial disorientation · Visual diffraction · Visual melting · Visual acuity enhancement · Dreaming enhancement · Peripheral misidentification · Vestibular distortion · Visual processing acceleration · Synesthesia · Visual magnification · Olfactory enhancement · Tinnitus · Flashbacks · Object transformations · Internal hallucinations · External hallucinations · Object activation · Visual recursion · Perspective hallucinations · Environmental orbism / cubism · Auditory hallucinations · Olfactory hallucination
Symmetrical texture repetition · Music enhancement · Tracers · Brightness alteration · Touch enhancement · After-images · Auditory enhancement · Environmental patterning · Light sensitivity · Sound sensitivity · Visual haze / noise · Visual morphing · Proprioceptive distortion · Auditory distortion · Auditory misinterpretation · Peripheral vision distortion · Spatial disorientation · Visual diffraction · Visual melting · Visual acuity enhancement · Dreaming enhancement · Peripheral misidentification · Vestibular distortion · Visual processing acceleration · Synesthesia · Visual magnification · Olfactory enhancement · Tinnitus · Flashbacks · Object transformations · Internal hallucinations · External hallucinations · Object activation · Visual recursion · Perspective hallucinations · Environmental orbism / cubism · Auditory hallucinations · Olfactory hallucination
Body high · Stimulation · Appetite suppression · Laughter fits · Tingling / electric sensations · Muscle tension · Wakefulness · Body schema distortion · Dizziness · Heart rate perception changes · Nausea · Tactile euphoria · Vibrations / buzzing · Bodily heaviness · Bodily lightness · Breathing alteration · Dry mouth · Physical fatigue · Restlessness · Yawning · Watery eyes · Excessive sweating · Headache · Insomnia · Muscle relaxation · Sedation · Sexual arousal enhancement · Trembling · Increased urination · Nasal congestion · Involuntary body movements · Kundalini-like energy · Nystagmus (eye wobbles) · Vasoconstriction · Vomiting · Motor control enhancement · Bodily dissociation · Tactile hallucination
Laughter fits · Tingling / electric sensations · Muscle tension · Wakefulness · Body schema distortion · Dizziness · Heart rate perception changes · Nausea · Tactile euphoria · Vibrations / buzzing · Bodily heaviness · Bodily lightness · Breathing alteration · Dry mouth · Physical fatigue · Restlessness · Yawning · Watery eyes · Excessive sweating · Headache · Insomnia · Muscle relaxation · Sedation · Sexual arousal enhancement · Trembling · Increased urination · Nasal congestion · Involuntary body movements · Kundalini-like energy · Nystagmus (eye wobbles) · Vomiting · Motor control enhancement · Bodily dissociation · Tactile hallucination
Immersion enhancement · Novelty enhancement · Thought connectivity · Aesthetic enhancement · Cognitive euphoria · Cognitive flexibility · Openness enhancement · Thought acceleration · Increased nature relatedness · Multiple thought streams · Creativity enhancement · Memory suppression · Thought loops · Cognitive impairment · Focus suppression · Humor enhancement · Cognitive fatigue · Confusion · Information processing suppression · Memory fragmentation · Synchronicity · Thought disorganization · Analysis enhancement · Cognitive dysphoria · Memory replays
Cognitive euphoria · Cognitive flexibility · Openness enhancement · Thought acceleration · Increased nature relatedness · Multiple thought streams · Creativity enhancement · Memory suppression · Thought loops · Cognitive impairment · Focus suppression · Humor enhancement · Cognitive fatigue · Confusion · Information processing suppression · Memory fragmentation · Synchronicity · Thought disorganization · Analysis enhancement · Cognitive dysphoria · Memory replays
Anxiety · Catharsis · Empathy enhancement · Dysphoria
Social connection · Trust enhancement · Communication enhancement · Flow state · Sociability enhancement · Boundary dissolution · Identity alteration · Ego dissolution
Sociability enhancement · Boundary dissolution · Identity alteration · Ego dissolution
Transpersonal visions · Entity contact · Death-rebirth sequence
Recursive awareness
Timeline
First alerts emerge as subtle mood shift, mild restlessness, and faint visual brightening. The free phenol form may produce slightly faster onset than psilocybin's phosphate ester prodrug.
Perceptual changes accelerate: colors intensify, surfaces begin to breathe, and body sensations emerge. Nausea or stomach discomfort is most likely during this phase. Anxiety may accompany the rising intensity.
Maximum perceptual, cognitive, and emotional intensity. Visual distortions, geometric patterning, thought connectivity, and emotional amplification reach their fullest expression. Time distortion is most pronounced.
Effects sustain at reduced intensity. Visual phenomena persist but are less immersive. Cognitive effects remain — thought connectivity and personal insight continue.
Gradual return toward baseline perception. Visual effects fade to subtle shimmering or color enhancement. Cognitive clarity returns progressively.
Residual mood elevation, heightened aesthetic appreciation, and mild cognitive openness may persist for several hours to a day. Some individuals report lingering visual sensitivity.
⚠ Do not drive or operate heavy machinery for the remainder of the day following ingestion.
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 or controlled toxicity data exist for 4-HO-DET in any species.[5] The toxic dose is genuinely unknown.safety citation needed At 20–25 mg, Shulgin reported nausea, tremors, jaw tension, appetite suppression, and increased urination; Leuner observed minimal aftereffects at therapeutic doses.
By class analogy, classical psychedelics have wide margins between active and dangerous doses — no confirmed human deaths from psilocybin toxicity alone have been documented.safety citation needed 4-HO-DET is expected to share this profile, but this has not been confirmed.
Heart and circulation
Serotonin receptor activation raises heart rate, blood pressure, and dilates pupils — expected for 4-HO-DET by class analogy.safety citation needed In healthy individuals at standard doses, clinical significance is likely minimal. Individuals with pre-existing heart conditions may face elevated risk.
Psychological Risks
Acute panic, paranoia, confusion, and deep dysphoria are the most common serious adverse events during psychedelic use, scaling with dose, mindset, and environment.[2] Persistent visual disturbances after the experience ends — a condition called HPPD — are an established risk with this drug class.[15][16] Psychotic episodes may be triggered in individuals with personal or family history of psychosis or bipolar disorder.
Tolerance & Dependence
Tolerance develops rapidly — a single dose can meaningfully reduce sensitivity within 24 hours,[17][6] and it is shared across all classical psychedelics including LSD, psilocybin, mescaline, and DMT.[6][17] Full sensitivity returns over roughly 7 days.
Classical psychedelics do not activate the brain's reward circuitry in the way associated with addiction, and no physical dependence or withdrawal has been documented.[7] Rapid tolerance itself limits compulsive redosing.
Drug Interactions
Serotonin syndrome risk
Tramadol blocks serotonin reuptake.[18] Combining it with 4-HO-DET loads the serotonin system from two directions at once, creating serious risk of dangerous overheating, muscle rigidity, agitation, and cardiovascular instability.[18][19]
MAOIs block the enzyme that breaks down serotonin and tryptamines.[20] Combining them with 4-HO-DET dramatically amplifies effects and creates significant risk of the same dangerous overheating response.
Effect attenuation
SSRIs and SNRIs taken chronically may blunt psychedelic effects through long-term changes to serotonin receptor sensitivity.[21] A theoretical serotonin syndrome risk also exists with acute co-administration.
Seizure risk
Lithium combined with classical psychedelics has been associated with seizures and erratic behavior.citation needed
Contraindications
The following contraindications are based on class-level evidence for serotonin agonist psychedelics. No substance-specific data exist for 4-HO-DET.
Absolute:
- Personal or family history of psychotic disorders
- Concurrent MAOI use — serotonin syndrome risk
- Concurrent tramadol use — serotonin syndrome risk[18]
- Concurrent lithium use — seizure riskcitation needed
Relative:
- Heart conditions — sympathomimetic effects may pose risksafety citation needed
- Bipolar disorder — risk of manic or psychotic episode
- Pregnancy — no safety data exist
- Concurrent SSRI/SNRI use — unpredictable effect modification and theoretical serotonin risk[21]
Harm Reduction[edit]
Forms & Identification
4-HO-DET degrades visibly when exposed to air. Any discoloration — darkening or browning — indicates oxidative breakdown and reduced potency.[5] Material that has changed color since purchase should be treated as partially degraded and inconsistent in strength.
Reagent testing confirms the presence of a 4-hydroxytryptamine but cannot distinguish between members of the series or assess purity. Quantitative analysis requires more advanced methods.
Guidelines
- Test all material with appropriate reagent kits before use
- Start with a low dose to assess individual sensitivity, particularly with material of unknown provenance
- Weigh doses with a milligram-precision scale — volumetric dosing is unreliable with air-sensitive compounds
- Allow at least 7 days between sessions for full tolerance reset
- Prepare the environment in advance: comfortable temperature, access to water, minimal obligations for the duration
- Eat lightly several hours beforehand to reduce nausea
- Keep a trusted, sober companion present — especially at unfamiliar doses
- Avoid redosing during the experience; rapid tolerance means additional material is unlikely to deepen effects and may extend duration unpredictably
Set & Setting
As a serotonergic psychedelic, 4-HO-DET's effects are substantially shaped by psychological state and physical environment. A calm, familiar setting with trusted companions reduces the likelihood of acute distress.
Avoid use during periods of emotional lability, unresolved anxiety, or significant life stress. First experiences benefit from a sober companion familiar with the psychedelic state.
Aftercare & integration. The hours and days following a psychedelic experience are a sensitive period. Allow time for rest and reflection — avoid demanding obligations on the day of use and ideally the following day. Journaling or drawing during the afterglow can help capture insights before they fade.
Difficult or confusing experiences benefit from processing with a trusted person or a therapist experienced with psychedelic integration. Persistent anxiety, depersonalization, or visual disturbances lasting more than a few days warrant professional consultation.
Recovery & Support
Classical psychedelics carry low addiction liability, and compulsive use patterns are rare. If use is becoming a way to avoid difficult emotions rather than explore them, or if frequency is increasing despite diminishing returns, reassessment is warranted. Support resources include psychedelic-informed therapists, peer support organizations such as the Fireside Project, and general mental health services. Psychological dependence on any substance — even one with no physical withdrawal — deserves the same attention as any other pattern of avoidance.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Most difficult psychedelic experiences are uncomfortable but not medically dangerous. Seek immediate help if the person shows signs of self-harm intent, complete disconnection from reality with dangerous behavior, seizures, sustained chest pain, or loss of consciousness.
Immediate steps:
- Call emergency services if the person is at risk of harming themselves or others, is unresponsive, or is experiencing seizures
- Move the person to a quiet, safe space away from hazards
- Speak calmly and reassuringly — remind them where they are, that they took a substance, and that the effects will end
- Do not physically restrain unless there is immediate danger of self-harm or harm to others
- Do not administer other substances to "counteract" the experience
- If the person is unconscious, place them in the recovery position and monitor breathing
What to tell the dispatcher: Name the substance (4-HO-DET, a psychedelic tryptamine), estimated dose, time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during drug-related emergencies.
Legal Status[edit]
4-HO-DET is rarely scheduled by name; it falls under generic tryptamine provisions, structural analog statutes, or blanket novel psychoactive substance legislation in most jurisdictions.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Not specifically scheduled | Not listed under the Controlled Substances Act. Subject to prosecution under the Federal Analogue Act (21 U.S.C. § 813) as a structural and pharmacological analog of psilocin (Schedule I) if intended for human consumption[1] |
| United Kingdom | Class A | Controlled under the Misuse of Drugs Act 1971 via the generic tryptamine catch-all clause. Additionally covered by the Psychoactive Substances Act 2016[1] |
| Canada | Not explicitly controlled | Not listed under the Controlled Drugs and Substances Act as of 2025citation needed |
| Germany | Likely controlled under NpSG | The Neue-psychoaktive-Stoffe-Gesetz (NpSG) covers structural classes of tryptamines with psychoactive properties. Specific verification for 4-HO-DET not confirmedcitation needed |
| Australia | Likely Schedule 9 | Probable classification under broad tryptamine provisions. Not directly verifiedcitation needed |
Analog and prodrug considerations
In jurisdictions with analog legislation — notably the United States — 4-HO-DET's close structural similarity to psilocin makes prosecution under analog statutes plausible.[1] The prodrug ethocybin (CEY-19) may face the same scrutiny. The 4-acetoxy analog (4-AcO-DET) functions as a prodrug for 4-HO-DET and may be treated identically under analog statutes.
Legal status varies by jurisdiction and changes without notice. This information is not legal advice.
references
- [1]
- [2] ^abcPassie T, Guss J, Krähenmann R (2022) Lower-Dose Psycholytic Therapy - A Neglected Approach — Frontiers in Psychiatry doi:10.3389/fpsyt.2022.1020505
- [3] ^abcHalberstadt AL, Koedood L, Powell SB, Geyer MA (2011) Differential contributions of serotonin receptors to the behavioral effects of indoleamine hallucinogens in mice — Journal of Psychopharmacology doi:10.1177/0269881110388326
- [4] ^abcdGatch MB, Hoch A, Carbonaro TM (2021) Discriminative Stimulus Effects of Substituted Tryptamines in Rats — ACS Pharmacology & Translational Science doi:10.1021/acsptsci.0c00173
- [5]
- [6] ^abcde 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