4-HO-MPT (4-hydroxy-N-methyl-N-propyltryptamine) is a synthetic psychedelic tryptamine in the 4-hydroxy tryptamine family — structurally a higher homologue of psilocin (4-HO-DMT) with a propyl group replacing one of the two methyl groups on the terminal nitrogen. It is the direct free-phenol active form (rather than a prodrug like its acetylated counterpart 4-AcO-MPT), meaning it interacts directly with serotonin receptors without requiring metabolic activation.
Community experience reports describe 4-HO-MPT as a characteristically visual tryptamine with a quality of richness and emotional openness. Like other members of the methyl-alkyl substituted 4-HO tryptamine series, it is generally considered to have a somewhat distinct texture from psilocin — the propyl chain alters the receptor binding profile in ways that may contribute to a modestly different subjective emphasis. Duration is typically 4–6 hours.
4-HO-MPT remains a relatively obscure compound even within the psychedelic research chemical community. Its documentation is sparse compared to psilocin, 4-HO-MiPT, or 4-HO-MET, and formal pharmacological data are absent. Community reports and microdosing accounts represent the primary available data on its effects.
Safety at a Glance
High Risk- Threshold: 5–10 mg | Common: 10–25 mg | Strong: 25–40 mg
- Limited documentation makes conservative starting doses (10–15 mg) strongly advisable.
- Toxicity: Acute Toxicity No formal toxicological data in humans. Class membership (4-hydroxy tryptamines, related to psilocin) ...
- Overdose risk: Fatal overdose from 4-HO-MPT alone, at doses within the typical recreational range, is extremely ...
If someone is in crisis, call 911 or Poison Control: 1-800-222-1222
Dosage
oral
Duration
oral
Total: 5 hrs – 7 hrsHow It Feels
The onset of 4-HO-MPT establishes itself within twenty-five to forty minutes as a gradual brightening of the perceptual field. Colors become more distinct, contrasts sharpen, and there is a growing sense of visual crispness, as though a slightly fogged lens has been wiped clean. A moderate body buzz accompanies this brightening — tingling in the extremities, a mild warmth in the core, and occasional muscle tension in the shoulders and jaw. Nausea is possible but generally mild.
Over the next thirty to sixty minutes, the visual effects develop into their full expression. Surfaces acquire a gentle, breathing quality, expanding and contracting in slow rhythms. Patterns emerge in textures — repeating geometric motifs that overlay the visual field with moderate intensity. The patterns tend toward symmetry and order: tessellations, grids, and concentric forms that have a balanced, almost calming aesthetic. Colors shift toward greater saturation without dramatic hue changes. Closed-eye visuals offer more complexity: layered geometric structures, slowly rotating mandalas, and fields of patterned color that respond to music and breath.
The peak, arriving around ninety minutes to two hours and lasting two to three hours, presents a moderate psychedelic headspace. Thoughts are gently altered — more associative, more reflective, more inclined toward abstract consideration — but cognitive function remains largely intact. There is no heavy ego dissolution or confrontational introspection, but rather a contemplative spaciousness that invites curiosity without demanding submission. The body feels moderately stimulated, and physical comfort depends on the setting — movement feels good, and stillness is equally acceptable. Music is enhanced in both emotional resonance and spatial quality.
The comedown is gradual and uncomplicated, the visual patterning fading over one to two hours into a gentle shimmer and then back to baseline. The total duration is five to six hours. The afterglow is mild and pleasant — a slight brightening of mood and a calm, rested quality that may linger into the following day. 4-HO-MPT occupies a middle ground among tryptamines: more engaging than the gentlest members of the family, less demanding than the deepest, and offering a balanced, visually oriented experience that rewards without overwhelming.
Subjective Effects
The effects listed below are based on the Subjective Effect Index (SEI), an open research literature based on anecdotal reports and personal analyses. They should be viewed with a healthy degree of skepticism. These effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects.
Physical Effects
Physical(5)
- Body load— A diffuse, heavy physical discomfort involving tension, pressure, and malaise in the torso and limbs...
- Increased heart rate— A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a fo...
- Muscle tension— Persistent partial contractions or tightening of muscles that produces uncomfortable stiffness, cram...
- Nausea— An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting...
- Pupil dilation— A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to drama...
Cognitive & Perceptual Effects
Visual(17)
- After images— A visual phenomenon in which a faint, ghostly imprint of a previously viewed image persists in the v...
- Brightness alteration— Perceived increase or decrease in environmental brightness beyond actual illumination levels, common...
- Colour enhancement— An intensification of the brightness, vividness, and saturation of colors in the external environmen...
- Colour shifting— The visual experience of colors on objects and surfaces cycling through continuous, fluid transforma...
- Depth perception distortions— Alterations in how the distance of objects within the visual field is perceived, causing layers of s...
- Diffraction— The experience of seeing rainbow-like spectrums of color and prismatic halos embedded within bright ...
- Drifting— The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow,...
- Geometry— The experience of perceiving complex, ever-shifting geometric patterns superimposed over the visual ...
- Internal hallucination— Vivid, detailed visual experiences perceived within an imagined mental landscape that can only be se...
- Pattern recognition enhancement— An increased ability and tendency to perceive meaningful patterns, faces, and images within ambiguou...
- Perspective distortions— Distortion of perceived depth, distance, and size of real objects, making things appear closer, furt...
- Perspective hallucination— A hallucinatory phenomenon in which the observer's visual perspective shifts from the normal first-p...
- Settings, sceneries, and landscapes— The perceived environment in which hallucinatory experiences take place, ranging from recognizable l...
- Symmetrical texture repetition— Textures appear to mirror and tessellate across surfaces in intricate, self-similar symmetrical patt...
- Tracers— Moving objects leave visible trails of varying length and opacity behind them, similar to long-expos...
- Transformations— Objects and scenery undergo perceived visual metamorphosis, smoothly shapeshifting into other recogn...
- Visual acuity enhancement— Vision becomes sharper and more defined than normal, as though a slightly blurry lens has been broug...
Cognitive(11)
- Anxiety— Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to...
- Cognitive euphoria— A cognitive and emotional state of intense well-being, elation, happiness, and joy that manifests as...
- Conceptual thinking— A shift in the nature of thought from verbal, linear sentence structures to intuitive, non-linguisti...
- Delusion— A delusion is a fixed, false belief that is held with unshakeable certainty and is impervious to con...
- Immersion enhancement— A heightened capacity to become fully absorbed and engrossed in external media such as music, films,...
- Introspection— An enhanced state of self-reflective awareness in which one feels drawn to examine their own thought...
- Memory suppression— A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ...
- Novelty enhancement— A feeling of increased fascination, awe, and childlike wonder attributed to everyday concepts, objec...
- Personal bias suppression— A decrease in the personal, cultural, and cognitive biases through which one normally filters their ...
- Thought loops— Becoming trapped in a repeating cycle of thoughts, actions, and emotions that loops every few second...
- Time distortion— Subjective perception of time becomes dramatically altered — minutes may feel like hours, or hours p...
Multi-sensory(1)
- Scenarios and plots— Scenarios and plots are the narrative structures that emerge within hallucinatory states — coherent ...
Transpersonal(2)
- Ego death— A profound dissolution of the sense of self in which personal identity, memories, and the boundary b...
- Unity and interconnectedness— A profound sense that identity extends beyond the self to encompass other people, nature, or all of ...
Pharmacology
Pharmacology
Mechanism of Action
4-HO-MPT (4-hydroxy-N-methyl-N-propyltryptamine) acts as an agonist at the serotonin 5-HT2A receptor, the molecular target responsible for the characteristic perceptual and cognitive effects of classical psychedelics. In head-twitch response (HTR) assays in C57BL/6J mice — the standard behavioral proxy for 5-HT2A-mediated psychedelic activity — 4-HO-MPT produces a dose-dependent response with an ED50 of approximately 1.92 micromol/kg .
N-Alkyl Substitution Effects
The compound features an asymmetric N-methyl-N-propyl substitution pattern on the terminal nitrogen. Systematic investigation by Klein et al. (2021) demonstrated that among N,N-disubstituted tryptamines, progressively lengthening one N-alkyl chain has relatively little effect on agonist potency at the 5-HT2A or 5-HT2B receptors, whereas potency at the 5-HT2C receptor tends to decline with bulkier substituents .
Serotonin Receptor Selectivity
Like other members of the 4-hydroxytryptamine series, 4-HO-MPT interacts with multiple serotonin receptor subtypes. Binding studies have shown that several 4-hydroxytryptamines — including 4-HO-MPT — display significantly higher affinities than DMT at the serotonin transporter (SERT) and at 5-HT receptor subtypes, suggesting a more complex pharmacological profile than simple 5-HT2A agonism alone .
References
- Klein AK, et al. Investigation of the structure-activity relationships of psilocybin analogues. ACS Pharmacol Transl Sci. 2021;4(2):533-542.
- Rickli A, et al. Pharmacological profiles of substituted tryptamines at 5-HT2AR, 5-HT2CR, 5-HT1AR, and SERT. J Pharmacol Exp Ther. 2024;388(1):275-286.
Detection Methods
Urine Detection
4-HO-MPT is not targeted by standard immunoassay-based urine drug screens. Specialized LC-MS/MS methods can detect 4-substituted tryptamine metabolites in urine for approximately 24 to 48 hours after ingestion. The detection window is relatively short compared to many other drug classes due to the rapid hepatic metabolism and renal clearance of tryptamine compounds. Psilocin (4-HO-DMT) is the most commonly targeted analyte in specialized tryptamine panels, and structural analogs may or may not be captured depending on the specific method.
Blood and Serum Detection
Blood detection windows for 4-HO-MPT are short, typically 4 to 12 hours after oral ingestion. Peak plasma concentrations of the active metabolite occur within 1 to 2 hours. The rapid first-pass metabolism means that parent compound concentrations in blood are often negligible for 4-AcO prodrugs, while 4-HO compounds themselves are measured directly. LC-MS/MS is required for reliable serum detection at the low concentrations involved.
Standard Drug Panel Inclusion
4-HO-MPT is NOT included on standard 5-panel, 10-panel, or 12-panel drug screens. Tryptamines do not cross-react with immunoassay targets for any of the standard panel analytes (amphetamines, cannabinoids, cocaine metabolites, opiates, PCP, benzodiazepines, or barbiturates). Detection requires a specific request for tryptamine or novel psychoactive substance testing at a reference laboratory. Some extended forensic panels include psilocin, which may capture certain 4-substituted tryptamines, but this coverage is not guaranteed for all structural variants.
Confirmatory Methods
Confirmatory identification of 4-HO-MPT relies on LC-MS/MS with reference standards specific to the compound or its expected metabolites. GC-MS can also be used following appropriate derivatization. Immunoassay-based methods for psilocybin and psilocin exist but show variable cross-reactivity with structural analogs and are not considered reliable for novel 4-substituted tryptamines. Reference laboratories specializing in novel psychoactive substances offer the most comprehensive detection capabilities.
Reagent Testing (Harm Reduction)
The Ehrlich reagent is the primary harm reduction tool for 4-HO-MPT. A sample placed on the reagent should produce a purple to violet color change, confirming the presence of an indole ring system characteristic of tryptamines. This reaction is shared with LSD, psilocybin, DMT, and all indole-containing compounds, so it confirms the general class but not the specific identity. The Hofmann reagent provides a confirmatory blue to violet reaction for tryptamines. The Marquis reagent typically shows no reaction or a dark brown discoloration with 4-substituted tryptamines. A positive Ehrlich result significantly reduces the probability that the substance is a dangerous substitute such as an NBOMe compound.
Interactions
| Substance | Status | Note |
|---|---|---|
| 3-FMA | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| 4-MMC | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| 8-Chlorotheophylline | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| Adrafinil | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| Anandamide | Caution | Cannabis can unpredictably intensify psychedelic effects and increase anxiety |
| Cannabis | Uncertain | — |
| 1,3-Butanediol | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 25E-NBOH | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 2C-T | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 2C-T-2 | Low Risk & Synergy | Cross-tolerance exists; effects compound |
History
History
4-HO-MPT was first synthesized and characterized as part of David B. Repke and W.J. Ferguson's systematic investigation of psilocin analogs, published in 1977. Working at the intersection of synthetic chemistry and psychopharmacology, Repke and colleagues prepared a series of 3-[2-(dialkylamino)ethyl]indol-4-ols — the chemical class to which all 4-hydroxytryptamines belong — exploring variations in the N-alkyl substituents to understand their effects on biological activity .
Unlike psilocin and psilocybin, which received extensive clinical investigation in the 1950s-1960s before regulatory restrictions curtailed research, 4-HO-MPT never progressed beyond initial characterization. It remained a footnote in the structure-activity relationship literature until the 2010s, when renewed interest in psychedelic pharmacology led Klein et al. (2021) to include it in a comprehensive study of psilocybin analog binding profiles and behavioral activity .
References
- Repke DB, Ferguson WJ. Psilocin analogs. 1. Synthesis of 3-[2-(dialkylamino)ethyl]- and 3-[2-(cycloalkylamino)ethyl]indol-4-ols. J Heterocyclic Chem. 1977;14:71-74.
- Klein AK, et al. Investigation of the structure-activity relationships of psilocybin analogues. ACS Pharmacol Transl Sci. 2021;4(2):533-542.
Harm Reduction
Dosing
- Threshold: 5–10 mg |Common: 10–25 mg |Strong: 25–40 mg
- Limited documentation makes conservative starting doses (10–15 mg) strongly advisable.
- Milligram-accurate scale required.
Microdosing Context
Community experience includes microdosing protocols with 4-HO-MPT. At sub-perceptual doses (1–3 mg), users report subtle mood enhancement and increased focus without full psychedelic effects. Standard microdosing cautions apply: monitor for tolerance accumulation, avoid daily use, maintain awareness of any mood destabilization.
Standard Psychedelic Harm Reduction
Test with Ehrlich reagent. Prepare set and setting carefully. Have a sober companion for first experiences. Avoid dangerous combinations (MAOIs, lithium). Reserve benzodiazepines as rescue medication if needed.
Toxicity & Safety
Acute Toxicity
No formal toxicological data in humans. Class membership (4-hydroxy tryptamines, related to psilocin) predicts low acute physiological toxicity at psychedelic doses. No documented fatalities.
Physiological Effects
Standard tryptamine sympathomimetic effects: mydriasis, tachycardia, mild blood pressure elevation, possible nausea during onset. The propyl chain may contribute to a more pronounced "body load" compared to psilocin in some users.
Psychological Risks
Standard psychedelic tryptamine contraindications apply: personal or family history of psychotic disorders, concurrent lithium or MAOI use. Anxiety, challenging experiences, and HPPD represent the primary psychological risks.
Addiction Potential
not habit-forming
Overdose Information
Fatal overdose from 4-HO-MPT alone, at doses within the typical recreational range, is extremely unlikely based on the available evidence for classical psychedelics. The therapeutic index for most psychedelics is very wide.
However, psychological emergencies can occur and require appropriate response:
- Severe anxiety, panic, or psychotic episodes
- Dangerous behavior due to impaired reality testing
- Self-harm in the context of a distressing experience
Emergency management: If someone is experiencing a severe adverse reaction, move them to a calm, quiet environment. Speak reassuringly. Do not restrain unless there is immediate danger. Benzodiazepines (if available and the person is conscious and able to swallow) can reduce acute anxiety. If psychotic symptoms, self-harm risk, or medical distress is present, seek emergency medical attention.
Medical attention: Seek help immediately for seizures, extremely elevated body temperature, signs of serotonin syndrome (agitation, tremor, diarrhea, rapid heart rate), or if the substance consumed is uncertain.
Tolerance
| Full | almost immediately after ingestion |
| Half | 3 days |
| Zero | 7 days |
Cross-tolerances
Legal Status
Due to its relative obscurity, the possession and sale of 4-HO-MPT is unscheduled in most countries.
Germany: 4-HO-MPT is controlled under the NpSG (New Psychoactive Substances Act) as of July 18, 2019. Production and import with the aim to place it on the market, administration to another person, placing it on the market and trading is punishable. Possession is illegal but not punishable. The legislator considers it possible that orders of 4-HO-MPT are punishable as an incitement to place it on the market.
Switzerland: 4-HO-MPT is not controlled under Buchstabe A, B, C and D. It could be considered legal.
United Kingdom: 4-HO-MPT is a Class A drug in the United Kingdom as a result of the tryptamine catch-all clause.
United States: 4-HO-MPT is unscheduled in the United States. It may be considered an analogue of psilocin (4-HO-DMT) which is a Schedule I drug under the Controlled Substances Act. As such, the sale for human consumption or the use for illicit non-medical or industrial intents and purposes could be prosecuted as crimes under the Federal Analogue Act.
Responsible use
Research chemical
Tryptamine
MPT
4-HO-MPT (Wikipedia)
4-HO-MPT (Erowid Vault)
4-HO-MPT (TiHKAL / Isomer Design)
The Big & Dandy 4-HO-MPT Thread (Bluelight)
Experience Reports (3)
Tips (3)
Psychedelic tolerance builds rapidly. Wait at least 1-2 weeks between uses of 4-HO-MPT for full tolerance reset. Taking the same dose the next day would require roughly double the amount for comparable effects.
Clear your schedule for the full duration of 4-HO-MPT plus afterglow. Do not plan any obligations, driving, or important decisions for the day. Having a time pressure or commitment hanging over you adds unnecessary anxiety.
Start with a low dose of 4-HO-MPT if it is your first time. You can always take more next time but you cannot take less once ingested. The difference between a comfortable and an overwhelming experience can be surprisingly small.
See Also
References (4)
- Psilocybin produces substantial and sustained decreases in depression and anxiety — Griffiths et al. Journal of Psychopharmacology (2016)paper
- Neural correlates of the LSD experience revealed by multimodal neuroimaging — Carhart-Harris et al. PNAS (2016)paper
- 4-HO-MPT - TripSit Factsheet
TripSit factsheet for 4-HO-MPT
tripsit - 4-HO-MPT - Wikipedia
Wikipedia article on 4-HO-MPT
wikipedia