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4-HO-MPT
4-hydroxy-N-methyl-N-propyltryptamine
4-HO-MPT (4-hydroxy-N-methyl-N-propyltryptamine) — also known as meprocin — is a synthetic psychedelic of the tryptamine class. It is a structural analog 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.
4-HO-MPT (4-hydroxy-N-methyl-N-propyltryptamine) — also known as meprocin — is an emerging synthetic psychedelic of the tryptamine class. It is a structural analog of psilocin, distinguished by a longer N-propyl chain and a broader receptor binding profile.[1] 4-HO-MPT is a 5-HT₂A receptor agonist, producing its effects by disrupting default-mode network integrity and cortical sensory filtering.
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First synthesized in 1981 by Repke, Ferguson, and Bates as part of systematic research into psilocin analogues,[1] it received only a single published human trial — Shulgin's 8 mg self-experiment documented in TiHKAL.[2] It remained obscure for decades before appearing on research chemical markets around 2016 and turning up in European law enforcement seizures by 2018.[3] No clinical research program has been launched.
Subjective effects include geometric visual patterns, brightened colors, mood elevation, and physical stimulation. The experience is broadly psilocybin-like but more energetic and outward-facing — stronger in the body than in the mind, with less introspective depth than its parent compound. Vertigo, insomnia, and underwhelming effects at doses others find fully psychedelic are commonly reported.
4-HO-MPT produces no physical dependence, and no fatality has been attributed to it. Its most distinctive risk is an unusually strong affinity for serotonin receptors linked to heart valve damage — shared with certain diet drugs — but whether occasional use poses a real cardiac risk is unknown.[4] Published research is extremely limited — what is known comes primarily from a 1981 synthesis paper, a brief self-experiment, and a single metabolic study.
History[edit]
Discovery
4-HO-MPT was first synthesized in 1981 by David B. Repke, W.J. Ferguson, and D.K. Bates as part of a systematic study of psilocin analogues with varied nitrogen substitution.[1] Alexander Shulgin included it as entry #23 in TiHKAL (1997) — one of the few entries where both dose and duration were listed as "unknown".[2] His single self-experiment at 8 mg produced mild visual distortion, prominent vertigo, and residual insomnia, but no notable philosophical depth.
Research chemical era
4-HO-MPT appeared on online research chemical markets around 2016[5] and was first identified in European law enforcement seizures in 2018.[3] Several jurisdictions have since placed it under controlled substance or novel psychoactive substance legislation. As of 2026, no clinical research program has been initiated.
The name meprocin follows the naming convention for 4-hydroxytryptamines: psilocin (N,N-dimethyl), metocin (N-methyl-N-ethyl), miprocin (N-methyl-N-isopropyl), and meprocin (N-methyl-N-propyl). In a 1985 follow-up study, Repke, Grotjahn, and Shulgin examined the closely related 4-HO-MiPT — differing only in propyl chain branching — and described it as producing "a classic hallucinogenic profile," calling it the most interesting compound in that series.[6] 4-HO-MPT has remained comparatively obscure, generating far less community interest than its branched-chain sibling.
Chemistry[edit]
Structural class
4-HO-MPT belongs to the 4-hydroxytryptamine subclass of substituted tryptamines. It sits between psilocin (symmetric N,N-dimethyl substitution) and longer-chain homologues such as 4-HO-DPT, distinguished by asymmetric substitution — one methyl and one n-propyl group on the terminal nitrogen. Its closest structural relative is 4-HO-MiPT, which carries an isopropyl rather than n-propyl chain.
Molecular identity
The molecular formula is C₁₄H₂₀N₂O (molecular weight 232.32 g/mol).[7] The molecule is built on a 4-hydroxyindole nucleus with an ethylamine tether at the 3-position, carrying one methyl and one n-propyl group on the terminal nitrogen. It is commercially available as the hydrofumarate salt for analytical and research purposes.[8]
Pharmacology[edit]
Mechanism of action
4-HO-MPT produces psychedelic effects by activating serotonin receptors in the cerebral cortex.[9][10] This disrupts the brain's default-mode processing and increases neural variability, producing the characteristic alterations in perception, cognition, and self-awareness. Its serotonin receptor affinity is moderate for its class.[4]
It engages a broader receptor footprint than psilocin, including serotonin receptors linked to heart valve function and histamine receptors.[4] It acts through direct receptor activation rather than by releasing serotonin into the synapse — SERT affinity is low.[4] This does not eliminate serotonin syndrome risk when combined with serotonin-elevating drugs.
Pharmacokinetics
No controlled pharmacokinetic study exists. Community timing places onset at 20–60 minutes, peak at 2–3 hours, and total duration at 5–7 hours.[11]inferred The liver processes the compound through several pathways, with a sugar-conjugated form being the most abundant breakdown product;[3] the enzyme MAO-A is also expected to contribute to breakdown.[12]inferred
Neuroscience[edit]
Where it acts
4-HO-MPT reduces connectivity within the brain's default-mode network — the system underlying self-referential thought and ego — while increasing communication between normally unconnected regions. This shift underlies the perceptual intensification and novel associations of the psychedelic state. Its histamine receptor engagement[4] may introduce a sedative quality not typical of other psychedelics.inferred
Why it matters
One framework proposes that serotonin receptor activation loosens the brain's predictive filtering, allowing raw sensation to override learned expectation — the neural basis of the psychedelic shift in consciousness. 4-HO-MPT's moderate receptor affinity suggests this occurs but may need higher doses to reach full intensity.inferred Whether its unusual receptor footprint changes the plasticity response compared to psilocin is unknown.
Does 4-HO-MPT's potent engagement of the heart-valve-linked serotonin receptor produce distinct effects in the brain during acute exposure? Does the histamine receptor activity change the brain's entropy signature compared to psychedelics without this engagement?
Subjective Effects[edit]
4-HO-MPT produces a psychedelic experience broadly similar to psilocybin mushrooms but with a notably more energetic physical tone. Visuals are prominent — colors deepen and surfaces shift — while the introspective weight is lighter than its parent compound. The experience is reported as outward-facing and sensory-rich rather than philosophically deep.
Its closest reference point is 4-HO-MiPT, which differs in a single chain branching and produces a similar duration and intensity profile. Against psilocin, it sits at slightly lower potency with more body stimulation and less of the inward gravity that defines psilocybin's character.
Synthesized in 1981 by Repke, Ferguson, and Bates during systematic research into psilocin analogues,[2] 4-HO-MPT received a single published human trial — Shulgin's 8 mg self-experiment in TiHKAL.[3] It remained obscure until appearing on research chemical markets circa 2016 and in European law enforcement seizures by 2018.[4] No clinical research program has been initiated.
Subjective effects include geometric visual patterns, color enhancement, physical stimulation, and mood elevation. The experience is described as broadly psilocybin-like but with a more energetic body feel and less introspective depth — a lighter, more outward-facing psychedelic state than its parent compound. Vertigo, insomnia, and underwhelming effects at doses others find fully active are reported unsought effects.
4-HO-MPT produces no physical dependence; tolerance resets within seven days via 5-HT₂A downregulation.[5] Its most distinctive risk is potent serotonin₂B receptor affinity — 14-fold stronger than at 5-HT₂A — raising an unresolved cardiac concern, as chronic 5-HT₂B agonism causes valve damage in other drug classes.[1] No controlled toxicity data, clinical trials, or systematic adverse event reporting exist.
History[edit]
Discovery
4-HO-MPT was first synthesized in 1981 by David B. Repke, W.J. Ferguson, and D.K. Bates at Wright State University, as part of a systematic study of psilocin analogues with varied N-alkyl substitution patterns.[2] Alexander Shulgin included it as entry #23 in TiHKAL (1997), though both dose and duration were listed as "unknown" — one of the few entries to carry this designation.[3] His single self-experiment at 8 mg produced mild visual distortion, prominent vertigo, and residual insomnia, but lacked the philosophical depth associated with psilocin.
Research chemical era
4-HO-MPT appeared on online research chemical markets around 2016[6] and was first identified in European law enforcement seizures in 2018.[4] Several jurisdictions have since placed it under controlled substance or novel psychoactive substance legislation. As of 2026, no clinical research program has been initiated for this compound.
The name meprocin follows the naming convention established for 4-hydroxytryptamines: psilocin (N,N-dimethyl), metocin (N-methyl-N-ethyl), miprocin (N-methyl-N-isopropyl), and meprocin (N-methyl-N-propyl). In a 1985 follow-up study, Repke, Grotjahn, and Shulgin examined the closely related 4-HO-MiPT — differing only in propyl chain branching — and described it as producing "a classic hallucinogenic profile," the most interesting compound in that series.[7] 4-HO-MPT has remained comparatively obscure, generating far less community interest than its branched-chain sibling.
Chemistry[edit]
Structural class
4-HO-MPT belongs to the 4-hydroxytryptamine subclass of substituted tryptamines. The parent scaffold is the indole ring system with a 2-aminoethyl side chain at C-3 and a hydroxyl group at C-4. 4-HO-MPT is distinguished by asymmetric N,N-dialkyl substitution: one methyl and one n-propyl group on the terminal nitrogen.
This places it between psilocin (symmetric N,N-dimethyl) and longer-chain homologues such as 4-HO-DPT (symmetric N,N-dipropyl). Its closest structural relative is 4-HO-MiPT, which carries an isopropyl rather than n-propyl chain — a subtle branching difference that alters pharmacological character.
Molecular identity
| Molecular formula | C₁₄H₂₀N₂O |
| Molecular weight | 232.32 g/mol |
The molecule consists of a 4-hydroxyindole nucleus with an ethylamine tether at the 3-position.[8] The terminal nitrogen carries one methyl group (C₁) and one n-propyl group (C₃), giving the molecule 14 carbons, 20 hydrogens, two nitrogens, and one oxygen.
Stereochemistry
4-HO-MPT is achiral — the molecule contains no stereocenters. The n-propyl chain introduces no asymmetric carbon, and no geometric isomerism is present. Stereoisomerism is not a pharmacological consideration.
Physical properties
| Melting point (free base) | 162–163°C |
| Appearance | White to off-white crystalline solid (free base) |
The melting point was reported in TiHKAL.[3] No published data exist on aqueous solubility, partition coefficient, or pKa. The 4-hydroxyl group is susceptible to oxidation under aerobic and acidic conditions — a property shared across all 4-hydroxytryptamines — which may degrade samples stored improperly.
The compound is commercially available as the hydrofumarate salt for analytical and research purposes.[9]
Pharmacology[edit]
Mechanism of action
4-HO-MPT produces psychedelic effects through agonism at serotonin 5-HT₂A receptors in the cerebral cortex — the same mechanism established for the 4-hydroxytryptamine class.[10][11] Activation of these receptors on cortical neurons disrupts default-mode network integrity and increases cortical entropy, producing the characteristic alterations in perception, cognition, and self-referential processing.
4-HO-MPT binds 5-HT₂A with moderate affinity for its class.[1] At higher doses, engagement of 5-HT₁A receptors may contribute sedative effects, as demonstrated for structurally similar tryptamines.[12] The compound also engages 5-HT₂B, 5-HT₆, and histamine H₁ receptors at significant concentrations — a broader receptor profile than psilocin.[1]
No functional activity data have been published for 4-HO-MPT specifically. By structural analogy with the class, it is expected to behave as a partial to full agonist at 5-HT₂A.[10][11] The compound induces the head-twitch response in mice, a behavioral marker of 5-HT₂A activation.[9]
Serotonin transporter affinity is low,[1] meaning 4-HO-MPT acts primarily as a receptor agonist without the serotonin-releasing properties of empathogenic tryptamines. This does not eliminate serotonin syndrome risk when combined with serotonin-elevating drugs.
Pharmacokinetics
No controlled human pharmacokinetic study exists for 4-HO-MPT. The oral route is the only documented administration method.
Metabolism has been characterized using pooled human liver cells with high-resolution mass spectrometry.[4] Three phase I metabolites were identified — including products of N-demethylation and N-oxidation — alongside phase II conjugates, with glucuronidation (sugar-group attachment for kidney clearance) being the most abundant metabolic product. This pattern mirrors that of the structural analog 4-HO-MET.[13]
Monoamine oxidase A (MAO-A) is expected to contribute to breakdown of 4-HO-MPT, as established for the tryptamine class broadly.[14] inferred Community-reported timing places onset at 20–60 minutes, peak effects at 2–3 hours, and total duration at 5–7 hours.[15] These values have not been verified in controlled settings.
Neuroscience[edit]
Where it acts
As a serotonin 2A receptor agonist, 4-HO-MPT is expected to reduce connectivity within the default-mode network — the brain system underlying self-referential thought and ego boundaries — while increasing communication between regions that do not normally interact. This shift from modular to globally connected brain activity underlies the perceptual intensification, novel associations, and ego dissolution characteristic of the psychedelic state. The compound's significant histamine H₁ receptor engagement[1] may introduce a sedative or attention-dampening tone not typical of psychedelics with minimal histaminergic activity. inferred
Why it matters
The REBUS (Relaxed Beliefs Under Psychedelics) framework proposes that 5-HT₂A agonism loosens the brain's predictive filtering, allowing raw sensory input to override learned expectations — the neural basis of the psychedelic shift in consciousness. 4-HO-MPT's moderate 5-HT₂A affinity suggests this effect occurs but may require higher doses to reach full intensity compared to more potent ligands.
As a 5-HT₂A agonist, the compound is also predicted to promote structural neuroplasticity — growth of new neural connections — though whether its unusual serotonin₂B engagement modulates this plasticity response differently from psilocin remains unknown. inferred
Does 4-HO-MPT's potent 5-HT₂B engagement produce central nervous system effects during acute exposure — and if so, does it alter the qualitative character of the experience? Does the histamine H₁ activity change the brain's entropy signature compared to psychedelics lacking this engagement?
Subjective Effects[edit]
The character of 4-HO-MPT is reported as broadly psilocybin-like but distinguished by a more stimulating physical tone and less introspective weight. At lower doses, visual enhancement and mood elevation predominate; at stronger doses, geometric patterning, perceptual distortion, and body load increase substantially. The experience appears sensitive to individual variation — some users report underwhelming effects at doses others find fully psychedelic — and follows the classical psychedelic pattern of strong set-and-setting dependence.
Relative to psilocin, 4-HO-MPT occupies a position of slightly lower potency with a reportedly more energetic body feel. Its closest comparator is 4-HO-MiPT, which differs only in propyl chain branching and produces a similar duration and intensity profile.
Effect Grid
At 20–30 mg, full psychedelic effects are present. Visual geometry, color enhancement, tracers, and visual drifting become prominent. Internal hallucinations may emerge during eyes-closed states. Time alteration is noticeable — minutes may feel stretched or compressed. Emotional enhancement intensifies, and pattern recognition enhancement colors perception of music, art, and conversation.
The body feel is distinctly stimulating compared to psilocybin mushrooms at equivalent psychedelic intensity. Pupil dilation is pronounced. Nausea may occur during the come-up phase but typically resolves by peak. Spontaneous body sensations are common — waves of warmth, tingling, or bodily pressures.
Full functional impairment should be expected for 5–7 hours. Cognitive and perceptual changes make driving unsafe. Aftereffects including mood shifts and possible insomnia may persist 2–12 hours beyond the main experience.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Perspective distortion · Symmetrical texture repetition · Brightness alteration · Music enhancement · Visual breathing · Sleep-transition hallucinations · Tracers · After-images · Visual diffraction · Auditory enhancement · Environmental patterning · Light sensitivity · Peripheral vision distortion · Sound sensitivity · Spatial disorientation · Visual haze / noise · Visual morphing · Touch enhancement · Vestibular distortion · Auditory distortion · Auditory misinterpretation · Dreaming enhancement · Ganzfeld effect · Holotropic state · Peripheral misidentification · Proprioceptive distortion · Visual melting · Visual acuity enhancement · Visual acuity suppression · Synesthesia · Visual processing acceleration · Visual magnification · Flashbacks · Internal hallucinations · Object transformations · Environmental orbism / cubism · Object activation · Visual recursion · External hallucinations · Perspective hallucinations · Auditory hallucinations · Visual flipping · Visual scenery slicing · Persisting hallucinations
Visual breathing · Sleep-transition hallucinations · Tracers · After-images · Visual diffraction · Auditory enhancement · Environmental patterning · Light sensitivity · Peripheral vision distortion · Sound sensitivity · Spatial disorientation · Visual haze / noise · Visual morphing · Touch enhancement · Vestibular distortion · Auditory distortion · Auditory misinterpretation · Dreaming enhancement · Ganzfeld effect · Holotropic state · Peripheral misidentification · Proprioceptive distortion · Visual melting · Visual acuity enhancement · Visual acuity suppression · Synesthesia · Visual processing acceleration · Visual magnification · Flashbacks · Internal hallucinations · Object transformations · Environmental orbism / cubism · Object activation · Visual recursion · External hallucinations · Perspective hallucinations · Auditory hallucinations · Visual flipping · Visual scenery slicing · Persisting hallucinations
Spontaneous body sensations · Heart rate perception changes · Nausea · Appetite suppression · Stimulation · Tactile euphoria · Tingling / electric sensations · Vibrations / buzzing · Wakefulness · Bodily heaviness · Bodily lightness · Bodily pressures · Body schema distortion · Breathing alteration · Dizziness · Dry mouth · Excessive sweating · Insomnia · Laughter fits · Muscle tension · Physical fatigue · Restlessness · Headache · Muscle relaxation · Sedation · Sexual arousal enhancement · Trembling · Abnormal heartbeat · Diarrhea · Involuntary body movements · Nystagmus (eye wobbles) · Respiratory stimulation · Yawning · Vomiting · Bodily dissociation · Tactile hallucination
Appetite suppression · Stimulation · Tactile euphoria · Tingling / electric sensations · Vibrations / buzzing · Wakefulness · Bodily heaviness · Bodily lightness · Bodily pressures · Body schema distortion · Breathing alteration · Dizziness · Dry mouth · Excessive sweating · Insomnia · Laughter fits · Muscle tension · Physical fatigue · Restlessness · Headache · Muscle relaxation · Sedation · Sexual arousal enhancement · Trembling · Diarrhea · Involuntary body movements · Nystagmus (eye wobbles) · Respiratory stimulation · Yawning · Vomiting · Bodily dissociation · Tactile hallucination
Cognitive euphoria · Novelty enhancement · Cognitive flexibility · Openness enhancement · Thought connectivity · Pattern recognition enhancement · Thought loops · Cognitive impairment · Immersion enhancement · Multiple thought streams · Creativity enhancement · Memory suppression · Focus suppression · Humor enhancement · Increased nature relatedness · Information processing suppression · Memory fragmentation · Synchronicity · Thought acceleration · Thought disorganization · Analysis enhancement · Analysis suppression · Cognitive fatigue · Confusion · Language suppression · Memory replays · Motivation suppression · Information processing enhancement · Cognitive dysphoria · Thought deceleration · Focus enhancement · Language enhancement · Memory enhancement · Motivation enhancement · Delusions · Amnesia
Openness enhancement · Thought connectivity · Pattern recognition enhancement · Thought loops · Cognitive impairment · Immersion enhancement · Multiple thought streams · Creativity enhancement · Memory suppression · Focus suppression · Humor enhancement · Increased nature relatedness · Information processing suppression · Memory fragmentation · Synchronicity · Thought acceleration · Thought disorganization · Analysis enhancement · Analysis suppression · Cognitive fatigue · Confusion · Language suppression · Memory replays · Motivation suppression · Information processing enhancement · Cognitive dysphoria · Thought deceleration · Focus enhancement · Language enhancement · Memory enhancement · Motivation enhancement · Amnesia
Simultaneous emotions · Anxiety · Catharsis · Anxiety suppression · Dysphoria
Dysphoria
Social connection · Trust enhancement · Flow state · Sociability enhancement · Communication suppression · Communication enhancement · Compulsive behavior reduction · Sociability suppression · Social disconnection · Ego inflation · Boundary dissolution · Cognitive disconnection · Ego dissolution · Identity alteration · Telepathic feelings
Communication suppression · Communication enhancement · Compulsive behavior reduction · Sociability suppression · Social disconnection · Ego inflation · Boundary dissolution · Cognitive disconnection · Ego dissolution · Identity alteration · Telepathic feelings
Time cessation
Transpersonal visions · Entity contact · Transpersonal memory access · Death-rebirth sequence · Voidness
Voidness
Lucidity enhancement · Recursive awareness
Timeline
Initial awareness emerges as mild body sensations, possible vertigo, and a subtle mood shift. Slight brightening of colors may be noticed.
Visual and cognitive effects progressively intensify. A stimulating body feel develops, distinguishing 4-HO-MPT from the heavier body load of psilocybin mushrooms. Nausea is most likely during this phase.
Full expression of psychedelic effects — visual geometry, color enhancement, emotional enhancement, and altered time perception. Pattern recognition enhancement and conceptual thinking are prominent.
Gradual reduction in intensity. Visual effects subside first while cognitive and emotional shifts linger. Stimulation diminishes but residual alertness may persist.
Residual mood elevation or fatigue. Subtle perceptual sensitivity may persist. Insomnia was noted in the TiHKAL report even at 8 mg.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Moderate
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- LSD · psilocin · psilo
Toxicity
No lethal dose has been established for 4-HO-MPT in any species. No fatalities attributed to the compound appear in the published literature or accessible case report databases.
Cardiovascular concerns: 5-HT₂B agonism
This is a safety-critical data gap — the risk is real by mechanism but entirely unquantified by evidence. safety citation needed
Acute toxicity
Class-level risks for 4-hydroxytryptamines at very high doses include elevated heart rate, elevated blood pressure, dangerous rises in body temperature, and serotonin syndrome — especially in combination with serotonin-elevating drugs.[13] No published case reports of 4-HO-MPT overdose or emergency presentation have been identified.
Psychological risks
No 4-HO-MPT-specific psychological adverse event data exist. Class-level risks for serotonergic psychedelics apply:
- Acute psychological distress — anxiety, paranoia, and thought loops are common at strong doses across all classical psychedelics. Limited user reports for 4-HO-MPT do not suggest unusual psychological volatility, but the evidence base is too thin to draw reliable conclusions.
- HPPD (Hallucinogen Persisting Perception Disorder) — persistent visual disturbances after the experience ends, documented for psilocin and other serotonergic psychedelics.[14] Class-level risk applies.
- Psychosis precipitation — a theoretical risk in individuals with personal or family history of psychotic disorders. No 4-HO-MPT-specific cases reported.
- Depersonalization/derealization — transient experiences are common during acute effects; persistent disorders are rare but documented for the class.
Tolerance and dependence
4-HO-MPT does not produce physical dependence. Classical psychedelics as a class show no withdrawal, no compulsive dose escalation, and no reinforcement in animal self-administration studies.[13]
Tolerance develops almost immediately through serotonin downregulation.[15] Full sensitivity returns within approximately seven days. Cross-tolerance exists with all serotonergic psychedelics — LSD, Psilocin, and DMT — acting through the same receptor.[15]
Drug Interactions
Serotonin syndrome risk
The primary pharmacological danger of combining 4-HO-MPT with other drugs is serotonin syndrome — a potentially life-threatening response involving overheating, muscle rigidity, and cardiovascular instability. Although 4-HO-MPT has low SERT affinity, its potent serotonin receptor activation creates additive serotonergic load when combined with drugs that increase synaptic serotonin.
Tramadol is classified as a dangerous interaction: it combines weak serotonin reuptake inhibitor with opioid effects.[16]
MAO inhibitors (including harmine and harmaline from Peganum harmala, phenelzine, and tranylcypromine) represent a dangerous interaction. MAO-A is expected to be a primary breakdown pathway for 4-HO-MPT;[12] blocking it dramatically amplifies and prolongs effects while sharply increasing serotonin syndrome risk.inferred
SSRIs and SNRIs create serotonin syndrome risk through mechanism overlap. They may also reduce subjective psychedelic effects through chronic serotonin receptor downregulation.
Seizure threshold interactions
Lithium combined with serotonergic psychedelics is associated with increased seizure risk. The mechanism is incompletely understood.citation needed
Cannabis
The interaction with cannabis is uncharacterized. Reports from other psychedelics suggest cannabis intensifies anxiety, perceptual effects, and paranoia during the peak.
Contraindications
7 knownNo substance-specific contraindication data exist. Class-level contraindications for serotonergic psychedelics apply:
- Personal or family history of psychotic disorders (absolute) — serotonin receptor activation may trigger or worsen psychosis in predisposed individuals
- Current MAOI therapy (absolute) — serotonin syndrome risk; MAO-A inhibition dramatically amplifies tryptamine effects
- Current SSRI/SNRI therapy (relative) — serotonin syndrome risk; may also reduce psychedelic effects
- Current lithium therapy (absolute) — increased seizure risk with serotonergic psychedelics
- Pre-existing heart valve disease (relative, specific to 4-HO-MPT) — the potent serotonin receptor affinity linked to valve function[4] warrants particular caution, though no clinical evidence of 4-HO-MPT-specific cardiac harm exists
- Pregnancy (absolute) — no safety data; precautionary exclusion
Harm Reduction[edit]
Forms & Identification
4-HO-MPT powder is visually indistinguishable from dozens of other white crystalline tryptamines. Given the compound's obscurity, the risk of receiving a mislabeled or substituted product is significant. Reagent testing — Marquis or Ehrlich — can confirm a tryptamine is present but cannot confirm which one.
Quantitative analysis through a drug checking service is the only reliable method of confirming identity and purity. Because 4-HO-MPT is active at low milligram amounts, even small purity variations meaningfully affect dosing intensity.
Guidelines
- Test every batch with at minimum an Ehrlich reagent; quantitative analysis through a drug checking service is strongly preferred
- Use a milligram-precision analytical balance — volumetric estimation and eyeballing are unreliable at this dose range
- Start with a low dose if unfamiliar with the compound or batch, as individual sensitivity varies considerably
- Eat lightly 2–3 hours before dosing to reduce nausea risk
- Have a sober, trusted companion present, particularly for first experiences or higher doses
- Prepare the environment: comfortable seating, water, blankets, calming music, and a way to change rooms if the space becomes uncomfortable
- Do not redose during the experience — tolerance develops rapidly and additional doses add duration and side effects more than intensity
Set & Setting
4-HO-MPT follows the classical psychedelic pattern of strong sensitivity to mindset and environment. A calm, familiar setting with a trusted sober companion significantly reduces the risk of acute psychological distress.
The experience may leave residual stimulation and difficulty sleeping. Scheduling accordingly — with a full free day and an unhurried evening — reduces downstream stress.
Aftercare & integration. The hours after a 4-HO-MPT experience may include residual stimulation and difficulty sleeping. Gentle activity, hydration, and a light meal support physical recovery. Avoid caffeine or other stimulants if insomnia is present.
Psychedelic experiences can surface unfamiliar emotions or perspectives. Journaling, conversation with a trusted person, or structured integration practices help process the content of the experience. If distressing thoughts or perceptual changes persist beyond 48 hours, consult a mental health professional experienced with psychedelic integration.
Recovery & Support
Classical psychedelics including 4-HO-MPT carry low risk of physical dependence, and compulsive use is self-limiting due to rapid tolerance. Psychological patterns of repeated use — using psychedelics to escape rather than explore — can still develop.
If psychedelic use is causing distress, interfering with daily life, or being used to avoid addressing mental health concerns, support is available through the Fireside Project (62-FIRESIDE), the MAPS integration list, and local psychedelic integration circles. General substance use support is available through SAMHSA's National Helpline (1-800-662-4357).
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Most difficult 4-HO-MPT experiences involve anxiety, confusion, and perceptual overwhelm — uncomfortable but not medically dangerous. Seek emergency help if any of the following occur: self-harm behavior or expressed intent, complete loss of contact with reality, seizure, chest pain, or dangerously high body temperature (skin hot to the touch with no cooling response).
Immediate steps:
- 1. Move the person to a calm, quiet space and reduce stimulation
- 2. Stay with them and speak in a calm, grounding voice
- 3. Do not restrain unless there is immediate danger of self-harm
- 4. If unconscious, place in the recovery position — on the side, airway clear
- 5. Call emergency services if any red-flag symptoms appear or the situation is not improving
What to tell the dispatcher: State the substance name (4-HO-MPT, a synthetic tryptamine), the amount taken if known, the time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Legal Status[edit]
4-HO-MPT occupies an ambiguous legal position in most jurisdictions. As a synthetic tryptamine with no approved medical use, it has been captured by generic scheduling provisions in some countries while remaining unscheduled in others. No international treaty specifically lists 4-HO-MPT.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Controlled under generic tryptamine definition (S.I. 2014/3277, effective January 7, 2015). Covers "any compound structurally derived from tryptamine or from a ring-hydroxy tryptamine by modification." Possession, supply, production, and import unlawful without Home Office licence[17][18] |
| Germany | NpSG (Neue-psychoaktive-Stoffe-Gesetz) | Controlled effective July 18, 2019. Production and supply punishable; possession not punishable under NpSG |
| United States | Not specifically scheduled | Potentially prosecutable under the Federal Analogue Act (21 U.S.C. § 813) as a structural and pharmacological analogue of psilocin (Schedule I). No DEA emergency scheduling action identified |
| Canada | Not explicitly controlled | Not listed under the Controlled Drugs and Substances Act (CDSA). Canada lacks a generic tryptamine scheduling provision |
| Australia | Unconfirmed | Status under TGA Poisons Standard could not be verified from official sources. citation needed |
Analogue act considerations
In the United States, the Federal Analogue Act extends Schedule I/II controls to substances substantially similar in structure or effect to a listed substance when intended for human consumption. 4-HO-MPT is unambiguously a structural analog of psilocin (Schedule I) — differing only in nitrogen substitution — and sale for human consumption would likely be prosecutable, though no precedent case involving 4-HO-MPT has been identified.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Moderate
- Withdrawal
- None
- Tolerance buildup
- rapid
- Tolerance reset
- 7 days
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- LSD · psilocin · psilo
Toxicity
No lethal dose has been established for 4-HO-MPT in any species. No formal toxicity assessment, safety evaluation, or systematic adverse event surveillance has been published. No fatalities attributed to 4-HO-MPT appear in the published literature or accessible case report databases.
Cardiovascular concerns: 5-HT₂B agonism
This represents a safety-critical data gap. No heart imaging, no animal cardiac tissue analysis, and no monitoring of cardiac outcomes among users has been conducted. safety citation needed
Acute toxicity
No published case reports of 4-HO-MPT overdose or emergency presentations were identified. Class-level acute risks for 4-hydroxytryptamines include serotonin syndrome (particularly in combination with serotonin-elevating drugs), rapid heart rate, elevated blood pressure, and dangerously high body temperature at very high doses.[16]
Psychological risks
No 4-HO-MPT-specific psychological adverse event data exist. Class-level risks for serotonergic psychedelics apply:
- Acute psychological distress — anxiety, paranoia, and thought loops are common at strong doses across all classical psychedelics. Limited user reports for 4-HO-MPT do not suggest unusual psychological volatility, but the evidence base is too thin to draw reliable conclusions.
- HPPD (Hallucinogen Persisting Perception Disorder) — documented for psilocin and other serotonergic psychedelics.[17] Class-level risk applies.
- Psychosis precipitation — a theoretical risk in individuals with personal or family history of psychotic disorders. No 4-HO-MPT-specific cases reported.
- Depersonalization/derealization — transient experiences are common during acute effects; persistent disorders are rare but documented for the class.
Tolerance and dependence
4-HO-MPT does not produce physical dependence. Classical psychedelics as a class show no withdrawal, no compulsive dose escalation, and no reinforcement in animal self-administration studies.[16]
Tolerance develops almost immediately after ingestion through 5-HT₂A downregulation.[5] Full sensitivity returns within approximately 7 days. Cross-tolerance exists with all serotonergic psychedelics acting through 5-HT₂A, including LSD, Psilocin, and DMT.[5]
Drug Interactions
Serotonin syndrome risk
The primary pharmacological danger of combining 4-HO-MPT with other drugs is serotonin syndrome. Although 4-HO-MPT has low SERT affinity, its potent post-synaptic serotonin receptor agonism creates additive serotonergic load when combined with drugs that increase synaptic serotonin.
Tramadol combines weak serotonin reuptake inhibitor with opioid effects and is classified as a dangerous interaction.[18]
MAO inhibitors (including harmine, harmaline from Peganum harmala, phenelzine, tranylcypromine) represent a dangerous interaction. MAO-A is expected to be a primary breakdown pathway for 4-HO-MPT;[14] inhibiting it would dramatically amplify and prolong effects while increasing serotonin syndrome risk. inferred
SSRIs and SNRIs create serotonin syndrome risk through mechanism overlap — elevated synaptic serotonin combined with potent post-synaptic agonism. SSRIs may also reduce subjective psychedelic effects through chronic 5-HT₂A downregulation.
Seizure threshold interactions
Lithium combined with serotonergic psychedelics is associated with increased seizure risk. The mechanism is incompletely understood. citation needed
Cannabis
The interaction with cannabis remains uncharacterized. Community reports from other psychedelics suggest cannabis intensifies anxiety, perceptual effects, and paranoia during the peak.
Contraindications
7 knownNo substance-specific contraindication data exist. Class-level contraindications for serotonergic psychedelics apply:
- Personal or family history of psychotic disorders (absolute) — 5-HT₂A agonists may trigger or worsen psychosis in predisposed individuals
- Current MAOI therapy (absolute) — serotonin syndrome risk; MAO-A inhibition dramatically amplifies tryptamine effects
- Current SSRI/SNRI therapy (relative) — serotonin syndrome risk; may also reduce psychedelic effects
- Current lithium therapy (absolute) — increased seizure risk with serotonergic psychedelics
- Pre-existing heart valve disease (relative, specific to 4-HO-MPT) — the potent 5-HT₂B affinity[1] warrants particular caution, though no clinical evidence exists for 4-HO-MPT-specific cardiac harm
- Pregnancy (absolute) — no safety data; 5-HT₂B is involved in cardiac development; precautionary exclusion
Harm Reduction[edit]
Forms & Identification
4-HO-MPT powder is visually indistinguishable from dozens of other white crystalline tryptamines. Given the compound's obscurity, the risk of receiving a mislabeled or substituted product is significant. Reagent testing provides only presumptive identification — a Marquis or Ehrlich result consistent with a tryptamine does not confirm which tryptamine is present.
Quantitative analysis via a drug checking service is the only reliable method of confirming identity and purity. Because 4-HO-MPT is active in the low-milligram range, even small purity variations meaningfully affect dosing.
Guidelines
- Test every batch with at minimum an Ehrlich reagent; quantitative analysis through a drug checking service is strongly preferred
- Use a milligram-precision analytical balance — volumetric estimation and "eyeballing" are unreliable at this dose range
- Start with a low dose if unfamiliar with the compound or batch, as individual sensitivity varies considerably
- Eat lightly 2–3 hours before dosing to reduce nausea risk
- Have a sober, trusted companion present, particularly for first experiences or higher doses
- Prepare the environment: comfortable seating, water, blankets, calming music, and a way to change rooms if the space becomes uncomfortable
- Do not redose during the experience — 5-HT₂A tolerance develops rapidly and additional doses add duration and adverse effects more than intensity
Set & Setting
4-HO-MPT follows the classical psychedelic pattern of strong sensitivity to mindset and environment. A calm, familiar setting with a trusted sober companion significantly reduces the risk of acute psychological distress. First experiences should be undertaken in a safe, private environment with no obligations for the remainder of the day.
The experience may leave residual stimulation and insomnia; scheduling accordingly — with a full free day and an unhurried evening — reduces downstream stress.
Aftercare & integration. The hours following a 4-HO-MPT experience may include residual stimulation and difficulty sleeping. Gentle activity, hydration, and a light meal support physical recovery. Avoid caffeine or other stimulants if insomnia is present.
Psychedelic experiences can surface unfamiliar emotions or perspectives. Journaling, conversation with a trusted person, or structured integration practices help process the content of the experience. If distressing thoughts or perceptual changes persist beyond 48 hours, consult a mental health professional experienced with psychedelic integration.
Recovery & Support
Classical psychedelics including 4-HO-MPT carry low risk of physical dependence, and compulsive use is self-limiting due to rapid tolerance. However, psychological patterns of repeated use — using psychedelics to escape rather than explore — can develop.
If psychedelic use is causing distress, interfering with daily life, or being used to avoid addressing mental health concerns, support is available through the Fireside Project (62-FIRESIDE), MAPS integration list, and local psychedelic integration circles. General substance use support is available through SAMHSA's National Helpline (1-800-662-4357).
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Recognizing an emergency: Most difficult 4-HO-MPT experiences involve anxiety, confusion, and perceptual overwhelm — uncomfortable but not medically dangerous. Seek emergency help if any of the following occur: self-harm behavior or expressed intent, complete loss of contact with reality, seizure, chest pain, or dangerously high body temperature (skin hot to the touch with no cooling response).
Immediate steps:
- 1. Move the person to a calm, quiet space and reduce stimulation
- 2. Stay with them and speak in a calm, grounding voice
- 3. Do not restrain unless there is immediate danger of self-harm
- 4. If unconscious, place in the recovery position (on their side, airway clear)
- 5. Call emergency services if any red-flag symptoms appear or if the situation is not improving
What to tell the dispatcher: State the substance name (4-HO-MPT, a synthetic tryptamine), the amount taken if known, the time of ingestion, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help during a drug emergency.
Legal Status[edit]
4-HO-MPT occupies an ambiguous legal position in most jurisdictions. As a synthetic tryptamine with no approved medical use, it has been captured by generic scheduling provisions in some countries while remaining unscheduled in others. No international treaty specifically lists 4-HO-MPT.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United Kingdom | Class A (Misuse of Drugs Act 1971) | Controlled under generic tryptamine definition (S.I. 2014/3277, effective January 7, 2015). Covers "any compound structurally derived from tryptamine or from a ring-hydroxy tryptamine by modification." Possession, supply, production, and import unlawful without Home Office licence[19][20] |
| Germany | NpSG (Neue-psychoaktive-Stoffe-Gesetz) | Controlled effective July 18, 2019. Production and supply punishable; possession not punishable under NpSG |
| United States | Not specifically scheduled | Potentially prosecutable under the Federal Analogue Act (21 U.S.C. § 813) as a structural and pharmacological analogue of psilocin (Schedule I). No DEA emergency scheduling action identified |
| Canada | Not explicitly controlled | Not listed under the Controlled Drugs and Substances Act (CDSA). Canada lacks a generic tryptamine scheduling provision |
| Australia | Unconfirmed | Status under TGA Poisons Standard could not be verified from official sources. citation needed |
Analogue act considerations
In the United States, the Federal Analogue Act extends Schedule I/II controls to substances "substantially similar" in structure or effect to a listed substance when intended for human consumption. 4-HO-MPT is unambiguously a structural analog of psilocin (Schedule I) — differing only in N-alkyl substitution — and produces pharmacologically similar effects. Sale for human consumption would likely be prosecutable under this provision, though enforcement requires case-by-case determination and no precedent case involving 4-HO-MPT has been identified.
Frequently asked questions
What is 4-HO-MPT?
4-HO-MPT is a synthetic substituted tryptamine psychedelic derived from psilocin, first synthesized in 1981. It acts as a 5-HT2A agonist with atypically potent 5-HT2B affinity and has not been studied in clinical trials.
How long does 4-HO-MPT last?
Total duration by route of administration — Oral: 5 – 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-HO-MPT?
Psychedex publishes a dosage table for 4-HO-MPT 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-HO-MPT?
The highest-severity documented interactions for 4-HO-MPT: 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-HO-MPT addictive?
Psychedex records tolerance and dependence data rather than a yes/no rating. Recorded tolerance indicators for 4-HO-MPT: tolerance builds rapid; full reset takes 7 days; cross-tolerance develops with LSD, psilocin, psilocybin, DMT, 4-AcO-DMT, 4-HO-MET, 4-HO-MiPT, mescaline. 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.
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- [5] ^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
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