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4-AcO-MET Facts

Psychedelic; Substituted tryptamine; Serotonin 2A receptor agonist

Description

4-AcO-MET (4-acetoxy-N-methyl-N-ethyltryptamine) — metacetin — is a synthetic psychedelic of the tryptamine class. It activates serotonin receptors in the brain, producing the visual and cognitive shifts characteristic of classical psychedelics.[1]

Subjective effects include geometric visual patterns, color enhancement, time alteration, elevated mood, and heightened emotional sensitivity. The experience is warm and visually rich — lighter than psilocybin, with a playful, aesthetic character that favors immersion over introspection.

4-AcO-MET produces no physical dependence, and no lethal dose has been established in any species.[2] The primary risks are psychological — panic, prolonged distress, or psychotic episodes — amplified by combining with MAOIs or tramadol, which can trigger a life-threatening serotonin overload.[3]

Dose and durationby route · individual sensitivity varies

Oral(mg)
Threshold< 5 mgLight10 – 20 mgCommon20 – 30 mgStrong30 – 50 mgHeavy50+ mg

Starts in 20 – 60 minLasts 4 – 6 hoursAfter-effects 2 – 4 hours

Body and dependence

Acute toxicity
Low
Chronic toxicity
Negligible
Physical dependence
None
Psychological dependence
Negligible
Withdrawal
None recorded
Compulsive redosing
Negligible

Tolerance

Builds
Rapid
Fully resets after
7 days
Carries over to
psilocybin; psilocin; LSD; DMT; mescaline; 4-AcO-DMT; 4-HO-MiPT

Effectslikely at a common dose

Perception
Color enhancement; Visual drifting; Color alteration; Tracers; Music enhancement; Geometry; Visual breathing; +23 possible, including Visual haze / noise, Spatial disorientation, Vestibular distortion
Body
Pupil dilation; Spontaneous body sensations; Body high; +22 possible, including Heart rate perception changes, Insomnia, Motor control impairment
Thinking
Novelty enhancement; Aesthetic enhancement; Introspection enhancement; +24 possible, including Cognitive impairment, Memory suppression, Decision impairment
Feeling
Emotional enhancement; Euphoria; +6 possible, including Emotional lability, Anxiety
Self
none likely · 7 possible, including Derealization, Depersonalization
Time
Time alteration; +2 possible, including Temporal disorientation
Transpersonal
none likely · 1 possible
Awareness
none likely · 3 possible

Who shouldn't take it

Absolute
Psychotic disorders; Pregnancy; Lithium co-administration; MAOI co-administration; Tramadol co-administration
Relative
Uncontrolled cardiovascular disease; Bipolar disorder

Combinations61 recorded

Lethal (1)
MAOIs
Dangerous (17)
Dopamine agonists; Lithium; MDMA, MDA; NRIs; GHB, Baclofen; GHB, GBL; Ibogaine; Ketamine, DXM, PCP; Local anesthetics; MDMA, Amphetamines; NDRIs (Wellbutrin); Psychedelics; Salvia, Ibogaine; SNRIs; SSRIs; Stimulants; Synthetic cannabinoids
Caution (37)
See full page: psychedex.org/substances/4-aco-met
Not graded (6)
Not listed never means safe.

Seek help immediately if

Most difficulty is psychological (intense fear, panic, confusion) and passes with calm support — the signs below mean seek emergency help:

  • Very high body temperature; hot, dry skin
  • Seizures
  • Chest pain; fast or irregular heartbeat
  • Severe muscle rigidity, tremor, or twitching (possible serotonin syndrome)
  • Cold, pale, or blue fingers/toes — severe vasoconstriction (notably NBOMe / DOx)
  • Persistent vomiting; unconsciousness; uncontrollable agitation or risk of self-harm

What to do

  1. Stay calm and reassure — remind them they took a drug and the effect will pass
  2. Move to a calm, quiet, safe space with low light; reduce noise and sensory input
  3. Keep them from harm — they may act on fear or confusion; stay with them, don't leave them alone
  4. Talk them down gently; don't grab or restrain unless they're in danger
  5. For the medical signs above (overheating, seizure, chest pain, vasoconstriction, unresponsive) call emergency services
  6. If overheating, cool the body; be ready to give rescue breaths / CPR

The experience is time-limited and usually resolves with calm reassurance in a safe setting — psychological first aid, not medication. Serious physical harm is uncommon for classic psychedelics (LSD, psilocybin) but real for some potent phenethylamines (NBOMe, DOx), where hyperthermia, seizures, and vasoconstriction warrant emergency care.

988 Suicide & Crisis LifelineFireside Project: 62-FIRESIDE

Version r1 · Not medical advice

References

  1. [1]
    ^McKenna DJ, Repke DB, Lo L, Peroutka SJ (1990) Differential interactions of indolealkylamines with 5-hydroxytryptamine receptor subtypes — Neuropharmacology PMID:2139186
  2. [2]
    ^Schlag AK, Aday J, Salam I, Neill JC, Nutt DJ (2022) Adverse effects of psychedelics: From anecdotes and misinformation to systematic science — Journal of Psychopharmacology doi:10.1177/02698811211069100
  3. [3]
    ^MacCallum CA, Lo LA, Pistawka CA, Deol JK (2022) Therapeutic use of psilocybin: Practical considerations for dosing and administration — Frontiers in Psychiatry doi:10.3389/fpsyt.2022.1040217
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