6-(2-Aminopropyl)benzofuran (6-APB) is a synthetic entactogen and benzofuran derivative that was first synthesized in 1993 by Andrew P. Monte and colleagues in the laboratory of David E. Nichols at Purdue University . Designed as a structural analog of MDA in which the methylenedioxy ring is replaced by a benzofuran moiety, 6-APB was created as part of a research program investigating how the dioxole ring oxygen atoms in MDA and MDMA contribute to their pharmacological activity and serotonergic selectivity .
6-APB acts primarily as a serotonin-norepinephrine-dopamine releasing agent (SNDRI), functioning as a substrate-type releaser at all three monoamine transporters. However, its pharmacological profile is distinctly serotonin-dominant, giving it a characteristically warm, emotionally expansive quality that users describe as deeply empathogenic with a gentle psychedelic undertone — more introspective and less stimulating than MDMA .
The compound gained widespread public attention between 2010 and 2012 when it appeared on the research chemical market under the brand name "Benzofury," primarily in the United Kingdom, where it was sold as a "legal high" in pellet and powder form before regulatory action. A significant pharmacological concern unique to 6-APB is its potent agonism at the5-HT2B serotonin receptor (Ki = 3.7 nM), a receptor subtype linked to drug-induced cardiac valvulopathy — the same mechanism responsible for the withdrawal of fenfluramine from the market . This raises important questions about the cardiovascular safety of repeated 6-APB use that remain unresolved due to a lack of controlled human studies.
References
Monte AP et al. Synthesis and pharmacological examination of benzofuran, indan, and tetralin analogues of 3,4-(methylenedioxy)amphetamine. J Med Chem. 1993;36(23):3700-3706. Nichols DE. Structure-activity relationships of serotonin 5-HT2A agonists. WIREs Membr Transp Signal. 2012;1(5):559-579. Rickli A et al. Pharmacological profile of novel psychoactive benzofurans. Br J Pharmacol. 2015;172(13):3412-3425. Rothman RB et al. Evidence for possible involvement of 5-HT2B receptors in the cardiac valvulopathy associated with fenfluramine. Circulation. 2000;102(23):2836-2841.
Safety at a Glance
High Risk- The Slow Onset is the Most Dangerous Feature
- Dosing -- Know Your Salt Form
- Toxicity: 5-HT2B Agonism and Cardiac Valvulopathy Risk The most distinctive safety concern with 6-APB is its potent agonism at ...
- Dangerous with: 25x-NBOH, 25x-NBOMe, Harmala alkaloid, Peganum harmala, MDMA
- Overdose risk: Recognizing a 6-APB Emergency 6-APB overdose presents as a serotonergic and sympathomimetic toxic...
If someone is in crisis, call 911 or Poison Control: 1-800-222-1222
Dosage
oral
Duration
oral
Total: 7 hrs – 10 hrsHow It Feels
The onset of 6-APB is famously slow. Ninety minutes, sometimes two hours, may pass before the full effects announce themselves, and this patience is not optional. The early phase is a gradual, almost imperceptible warming: a slight softening of mood, a faint glow in the chest, a sense that something is building beneath the surface. Colors may begin to shift subtly, gaining warmth and saturation. The temptation to redose during this extended come-up has caused many to overshoot their intended experience.
When 6-APB finally arrives in earnest, it arrives with authority. A rolling wave of empathogenic warmth floods through the body, accompanied by visual changes that set this compound apart from pure entactogens. Colors become vivid and deeply saturated, with a particular emphasis on warm tones: golds, ambers, and reds that seem to glow from within. Surfaces may shimmer or breathe gently, and there is a dreamlike, slightly psychedelic quality to perception that gives the experience a richness and depth that MDMA does not approach. Music becomes extraordinary, simultaneously emotional, visual, and physical. Social warmth deepens into genuine intimacy, and conversations acquire layers of meaning and mutual understanding.
At the peak, three to four hours in, 6-APB occupies unique territory at the intersection of empathogen and psychedelic. The emotional openness is profound, comparable to MDMA at its best, but the perceptual enrichment adds a dimension that makes the experience feel more expansive and less purely social. The body is warm and grounded, sometimes uncomfortably so. Jaw tension is significant, body temperature runs high, and nausea is not uncommon. The headspace is clear but emotionally saturated, and there is a quality of visionary intimacy that many find deeply meaningful.
The duration of 6-APB is substantial, typically seven to ten hours of noticeable effects. The decline is very gradual, the empathogenic warmth slowly fading while the visual enrichment lingers. The comedown carries a serotonergic weight that can persist for two to three days: fatigue, emotional flatness, and a muted quality to pleasure and motivation. The body demands rest and nutrition. But the experience itself, with its unique blend of emotional depth and perceptual beauty, is often described as among the most memorable in the entactogen class.
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(31)
- Abnormal heartbeat— Abnormal heartbeat (arrhythmia) is any deviation from the heart's normal rhythm — including beats th...
- Appetite suppression— A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete d...
- Bodily control enhancement— Bodily control enhancement is the subjective feeling of improved physical precision, coordination, a...
- Brain zaps— Brain zaps are sudden, brief, electrical shock-like sensations that originate in the head and someti...
- Dehydration— A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical d...
- Difficulty urinating— Difficulty urinating, also known as urinary retention, is the experience of being unable to easily p...
- Dry mouth— A persistent, uncomfortable reduction in saliva production causing the mouth and throat to feel parc...
- Excessive sweating— Profuse perspiration exceeding normal thermoregulatory needs, common with stimulants and empathogens...
- Excessive yawning— Involuntary, repeated yawning that occurs far more frequently than normal and often without the usua...
- Increased blood pressure— Increased blood pressure (hypertension) is an elevation of arterial pressure above the normal 120/80...
- Increased bodily temperature— Increased bodily temperature (hyperthermia) is an elevation of core body temperature above the norma...
- Increased heart rate— A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a fo...
- Increased libido— A marked enhancement of sexual desire, arousal, and sensitivity to erotic stimuli that can range fro...
- Insomnia— A persistent inability to fall asleep or maintain sleep despite physical tiredness, often characteri...
- Laughter fits— Spontaneous, uncontrollable, and often prolonged episodes of intense laughter that erupt without any...
- Nausea— An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting...
- Nystagmus— Rapid, involuntary oscillating movements of the eyes that cause vision to vibrate and blur, often ma...
- Physical euphoria— An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity...
- Pupil dilation— A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to drama...
- Respiratory depression— A dangerous slowing and shallowing of breathing that can progress from barely noticeable reductions ...
- Sedation— A state of deep physical and mental calming that manifests as a progressive desire to remain still, ...
- Seizure— Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threa...
- Serotonin syndrome— Serotonin syndrome is a potentially fatal medical emergency caused by excessive serotonergic activit...
- Stamina enhancement— Stamina enhancement is an increase in one's ability to sustain physical and mental exertion over ext...
- Stimulation— A state of heightened physical and mental energy characterized by increased wakefulness, elevated mo...
- Teeth chattering— Teeth chattering is an involuntary, rhythmic movement of the jaw that produces rapid clicking or cha...
- Teeth grinding— An involuntary clenching and rhythmic grinding of the jaw muscles, known clinically as bruxism, that...
- Temperature regulation disruption— Impaired thermoregulation causing unpredictable fluctuations between feeling hot and cold, with risk...
- Temporary erectile dysfunction— Temporary erectile dysfunction is the substance-induced inability to achieve or sustain a penile ere...
- Vasoconstriction— A narrowing of blood vessels throughout the body that produces sensations of cold extremities, tingl...
- Vibrating vision— Vibrating vision is the subjective experience of the visual field rapidly oscillating or shaking due...
Tactile(1)
- Tactile enhancement— The sense of touch becomes dramatically heightened, making physical contact feel intensely pleasurab...
Cognitive & Perceptual Effects
Visual(10)
- Drifting— The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow,...
- External hallucination— A visual hallucination that manifests within the external environment as though it were physically r...
- 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 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...
Cognitive(33)
- Amnesia— A complete or partial inability to form new memories or recall existing ones during and after substa...
- Anxiety— Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to...
- Anxiety suppression— A partial to complete suppression of anxiety and general unease, producing a calm, relaxed mental st...
- Cognitive euphoria— A cognitive and emotional state of intense well-being, elation, happiness, and joy that manifests as...
- Cognitive fatigue— Mental exhaustion and difficulty sustaining thought after intense cognitive experiences, common duri...
- Compulsive redosing— An overwhelming, difficult-to-resist urge to continuously take more of a substance in order to maint...
- Creativity enhancement— An increase in the ability to imagine new ideas, overcome creative blocks, think about existing conc...
- Delusion— A delusion is a fixed, false belief that is held with unshakeable certainty and is impervious to con...
- Depression— A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasur...
- Derealization— A perceptual disturbance in which the external world feels profoundly unreal, dreamlike, or artifici...
- Disinhibition— A marked reduction in social inhibitions, self-consciousness, and behavioral restraint that manifest...
- Dream potentiation— Enhanced dream vividness, complexity, and recall, often occurring as REM rebound after discontinuing...
- Empathy enhancement— A state of intensified compassion and emotional openness in which one feels deeply connected to othe...
- Focus enhancement— An enhanced ability to direct and sustain attention on a single task or stimulus with unusual clarit...
- Immersion enhancement— A heightened capacity to become fully absorbed and engrossed in external media such as music, films,...
- Increased sense of humor— A general amplification of one's sensitivity to finding things humorous and amusing, often causing p...
- Irritability— Irritability is a sustained state of emotional reactivity in which the threshold for annoyance, frus...
- Mania— Abnormally elevated mood, energy, and activity with impulsive behavior and grandiosity, associated w...
- Memory suppression— A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ...
- Mindfulness— Mindfulness in the substance context refers to a state of heightened present-moment awareness in whi...
- Motivation enhancement— A heightened sense of drive, ambition, and willingness to accomplish tasks, making productive effort...
- Motivation suppression— Motivation suppression is a state of diminished drive and willingness to engage in goal-directed beh...
- Novelty enhancement— A feeling of increased fascination, awe, and childlike wonder attributed to everyday concepts, objec...
- Panic attack— A panic attack is a discrete episode of acute, overwhelming fear or terror that arises suddenly and ...
- Personal meaning enhancement— Personal meaning enhancement is a state in which everyday events, coincidences, song lyrics, environ...
- Psychosis— Psychosis is a serious psychiatric state involving a fundamental break from consensus reality — char...
- Suicidal ideation— Suicidal ideation is the emergence of thoughts, urges, or preoccupations centered on ending one's ow...
- Thought acceleration— The experience of thoughts occurring at a dramatically increased rate, as if the mind has been shift...
- Thought deceleration— The experience of thoughts occurring at a markedly reduced pace, as if the mind has been placed into...
- Thought disorganization— Thought disorganization is a cognitive impairment in which the normal capacity for structured, seque...
- 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...
- Wakefulness— An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation ...
Auditory(4)
- Auditory distortion— Auditory distortion is the experience of sounds becoming warped, pitch-shifted, flanged, or otherwis...
- Auditory enhancement— Auditory enhancement is a heightened sensitivity and appreciation of sound in which music, voices, a...
- Auditory hallucination— Auditory hallucination is the perception of sounds that have no external source — hearing music, voi...
- Auditory misinterpretation— Auditory misinterpretation is the brief, spontaneous misidentification of real sounds as entirely di...
Multi-sensory(2)
- Memory replays— Memory replays are vivid, multisensory re-experiences of past events that go far beyond normal recal...
- Scenarios and plots— Scenarios and plots are the narrative structures that emerge within hallucinatory states — coherent ...
Transpersonal(2)
- Existential self-realization— A sudden, visceral realization of the profound significance and improbability of one's own existence...
- Unity and interconnectedness— A profound sense that identity extends beyond the self to encompass other people, nature, or all of ...
Pharmacology
Mechanism of Action
6-APB functions as a substrate-type monoamine releasing agent, entering presynaptic neurons via monoamine transporters and triggering non-exocytotic release of neurotransmitters into the synaptic cleft. In rat brain synaptosome studies, 6-APB demonstrates potent activity at all three monoamine transporters with EC50 values of approximately 10 nM at the dopamine transporter (DAT), 14 nM at the norepinephrine transporter (NET), and 36 nM at the serotonin transporter (SERT) . While these values suggest broad monoamine activity, the functional serotonin release in vivo appears to dominate the subjective experience.
Receptor Binding Profile
Beyond transporter-mediated monoamine release, 6-APB exhibits a rich receptor binding profile that distinguishes it from simpler stimulants. Most notably, 6-APB is a potent agonist at the 5-HT2B receptor with a Ki of 3.7 nM — substantially more potent than fenfluramine's active metabolite norfenfluramine at this same receptor . This 5-HT2B affinity is a defining pharmacological feature with significant safety implications (see Toxicity section).
6-APB also demonstrates meaningful agonist activity at 5-HT2A and 5-HT2C receptors, which likely contributes to the mild psychedelic character that users report — visual enhancement, pattern recognition, and introspective depth that distinguish the 6-APB experience from pure MDMA-like empathogens .
Comparison with MDA and MDMA
Structure-activity studies from the Nichols laboratory demonstrated that replacing the methylenedioxy ring of MDA with a benzofuran moiety modulates selectivity for serotonin versus catecholamine uptake carriers. The orientation and position of ring oxygen atoms play a critical role in determining this selectivity profile . In functional assays, 5-APB and 6-APB mimic the effects of MDA on monoamine transmission in male rats, producing comparable increases in extracellular serotonin, dopamine, and norepinephrine in the nucleus accumbens .
Pharmacokinetics
6-APB has a notably slow onset of action (1-2 hours when taken orally), which has led to dangerous redosing when users assume their initial dose was insufficient. The prolonged onset likely reflects slower absorption kinetics and the time required for substrate-type release to reach peak effect. Duration of action ranges from 5-8 hours, with some users reporting residual effects lasting 10+ hours .
References
Monte AP et al. Synthesis and pharmacological examination of benzofuran, indan, and tetralin analogues of 3,4-(methylenedioxy)amphetamine. J Med Chem. 1993;36(23):3700-3706. Rickli A et al. Pharmacological profile of novel psychoactive benzofurans. Br J Pharmacol. 2015;172(13):3412-3425. Release.org.uk. 6-APB & 5-APB ('Benzofury') Pharmacology. Drug Science Advisory. Dawson P et al. The psychoactive aminoalkylbenzofuran derivatives, 5-APB and 6-APB, mimic the effects of MDA on monoamine transmission in male rats. Neuropharmacology. 2021;180:108291.
Detection Methods
Standard Drug Screening
6-APB is not detected by standard immunoassay drug screening panels, which are designed to identify common drugs of abuse such as amphetamines, opioids, benzodiazepines, and cannabinoids. However, due to its structural similarity to amphetamine, 6-APB may producefalse-positive results on some amphetamine/ecstasy immunoassay platforms, particularly the CEDIA Amphetamine/Ecstasy and EMIT d.a.u. Amphetamine Class assays, which have demonstrated cross-reactivity with structurally related novel psychoactive substances .
Confirmatory Analytical Methods
Definitive identification of 6-APB requires targeted analytical techniques. LC-MS/MS (liquid chromatography-tandem mass spectrometry) andGC-MS (gas chromatography-mass spectrometry) are the primary confirmatory methods used in forensic and clinical toxicology. Validated HPLC-MS/MS methods can simultaneously determine 5-APB and 6-APB in blood, other body fluids, hair, and various tissues, with a lowest limit of quantification (LLOQ) of 1 ng/mL across a linear range of 1-1000 ng/mL .
Metabolite-Based Detection
Studies using rat urine models and human liver microsome preparations have characterized the metabolic fate of 6-APB, identifying phase I and phase II metabolites that can serve as urinary biomarkers. For 6-APB, quantification of the parent compound in urine is considered a reliable detection strategy. Differentiation between the 5-APB and 6-APB isomers requires high-resolution mass spectrometry (LC-HR-MSn) .
References
Ellefsen KN et al. Novel psychoactive substance screening in immunoassays. Clin Chem. 2014;60(12):1510-1517. Ambach L et al. Simultaneous determination of 5- and 6-APB in blood, other body fluids, hair and various tissues by HPLC-MS/MS. J Anal Toxicol. 2022;46(3):264-272. Welter J et al. Metabolic fate and detectability of the benzofuran designer drugs 6-APB and 6-MAPB using GC-MS and LC-HR-MSn. Anal Bioanal Chem. 2015;407(12):3457-3470.
Interactions
| Substance | Status | Note |
|---|---|---|
| 25x-NBOH | Dangerous | — |
| 25x-NBOMe | Dangerous | — |
| Harmala alkaloid | Dangerous | Extreme serotonin syndrome risk; potentially fatal — MAOIs massively potentiate MDMA |
| Peganum harmala | Dangerous | Extreme serotonin syndrome risk; potentially fatal — MAOIs massively potentiate MDMA |
| MDMA | Unsafe | — |
| 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 |
| Alcohol | Uncertain | — |
| Dissociatives | 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 |
History
Origins in Academic Research
6-APB was first synthesized in 1993 by Andrew P. Monte, Danuta Marona-Lewicka, Nicholas V. Cozzi, and David E. Nichols at Purdue University's Department of Medicinal Chemistry and Pharmacognosy. The work was published in the Journal of Medicinal Chemistry as part of a structure-activity relationship study examining how the methylenedioxy ring system in MDA contributes to its pharmacological effects . By replacing this ring with benzofuran, indan, and tetralin scaffolds, the researchers aimed to understand which structural features were essential for serotonergic selectivity and entactogenic activity. The study found that the position and orientation of ring oxygen atoms significantly modulated selectivity for 5-HT versus catecholamine uptake carriers.
Emergence as a Research Chemical (2010-2012)
6-APB remained an obscure academic compound for nearly two decades until it appeared on the research chemical market around 2010, sold primarily in the United Kingdom under the brand name "Benzofury" . It was marketed as a "legal alternative" to MDMA and MDA, exploiting the fact that its benzofuran structure was not covered by existing drug scheduling legislation in many jurisdictions. The 2012 Global Mixmag/Guardian Drugs Survey found that 3.2% of UK respondents reported lifetime use of Benzofury products .
Regulatory Response
Following reports of adverse events and fatalities, the UK Advisory Council on the Misuse of Drugs (ACMD) recommended control measures. On June 10, 2013, 6-APB and several related benzofuran compounds were classified as Temporary Class Drugs in the UK. They were subsequently permanently scheduled under the Misuse of Drugs Act, and the 2016 Psychoactive Substances Act provided blanket coverage for all novel psychoactive substances .
References
Monte AP et al. Synthesis and pharmacological examination of benzofuran, indan, and tetralin analogues of 3,4-(methylenedioxy)amphetamine. J Med Chem. 1993;36(23):3700-3706. Release.org.uk. 6-APB & 5-APB ('Benzofury'). Drug Information Service. ACMD. Benzofuran compounds report. Advisory Council on the Misuse of Drugs. UK Government. 2013.
Harm Reduction
The Slow Onset is the Most Dangerous Feature
6-APB takes 1-2 hours to reach full effects, sometimes longer. This is not MDMA's 30-45 minute come-up. Users who expect a quicker onset routinely redose too early, stacking doses that then hit simultaneously with potentially dangerous intensity. Set a timer when you dose. Do not redose for at least 2 hours. Many experienced users advise against redosing at all, given the 7-10 hour duration.
Dosing -- Know Your Salt Form
6-APB has been sold in three salt forms with dramatically different potencies by weight:
- Hydrochloride (HCl): Most potent by weight. Common dose: 80-120 mg
- Succinate: Roughly 60-70% the potency of HCl by weight. Common dose: 100-150 mg
- Fumarate: Roughly 70-80% the potency of HCl by weight. Common dose: 100-140 mg
If you do not know which salt form you have, start at the low end (80-100 mg) and wait the full 2 hours. The difference between a comfortable experience and an overwhelming one is often just 20-30 mg, and you cannot undo an excessive dose once it hits.
The 5-HT2B Problem -- Cardiac Risk With Repeated Use
This is 6-APB's unique and most serious long-term concern. 6-APB is a potent agonist at the serotonin 5-HT2B receptor (Ki = 3.7 nM) -- more potent than norfenfluramine, the drug metabolite that caused the fenfluramine cardiac valvulopathy epidemic of the 1990s. The 5-HT2B receptor sits on cardiac valve interstitial cells, and chronic activation drives fibrotic thickening that damages heart valves. The fenfluramine cases involved daily use over months to years, and nobody knows whether intermittent recreational use of 6-APB reaches the threshold for clinically meaningful valve damage. But the pharmacological signal is strong enough that the FDA has designated 5-HT2B as an explicit "anti-target" that all new serotonergic drugs must be screened against.
Practical implications:
- Space sessions as far apart as possible -- months, not weeks
- If you use 6-APB regularly (monthly or more frequently), consider requesting an echocardiogram from your doctor to monitor valve function
- Limit lifetime exposure. This is not a substance to use frequently over years
- Individuals with pre-existing heart valve conditions should avoid 6-APB entirely
Temperature and Hydration
6-APB raises core body temperature through serotonergic disruption of thermoregulation. Community reports frequently describe 6-APB as feeling "warmer" than MDMA. In dance environments, this can escalate to dangerous hyperthermia.
- Cool down every 30-45 minutes if active
- Drink approximately 500ml per hour of moderate activity -- not more. Hyponatremia is a risk with all serotonin-releasing empathogens
- If someone stops sweating in a hot environment, begin active cooling immediately and call for medical help
Test Your Substance
6-APB has been sold in varying purity and is sometimes confused with or substituted for its isomer 5-APB (which has a different effect profile). Reagent testing provides some differentiation:
- Marquis: 6-APB produces a dark purple/black reaction (similar to MDMA/MDA)
- Mandelin: Dark brown/black
- Mecke: Dark green/black
- Reagents alone cannot distinguish 6-APB from 5-APB with certainty. If precise identification matters, laboratory analysis (e.g., through DanceSafe or Energy Control) is recommended
Dangerous Combinations
- MAOIs (phenelzine, moclobemide, Syrian rue) --potentially fatal serotonin syndrome. Absolute contraindication
- MDMA or MDA -- compounded serotonergic neurotoxicity, hyperthermia, and cardiovascular strain. Taking 6-APB and MDMA together is particularly risky because the combined duration can exceed 12 hours of sustained monoamine flooding
- Other stimulants (cocaine, amphetamine, mephedrone) -- additive cardiovascular stress
- Tramadol -- serotonin syndrome risk plus lowered seizure threshold
- SSRIs/SNRIs -- will blunt effects and may precipitate serotonin syndrome. SSRIs must be discontinued for an appropriate washout period before use, not the day before
- Alcohol -- masks overheating, compounds dehydration, impairs judgment
- Other 5-HT2B agonists -- any substance with 5-HT2B activity (including some triptans and ergot derivatives) compounds the cardiac valve risk
The Comedown
6-APB's comedown is widely described as more prolonged than MDMA's, likely owing to the longer duration of serotonin depletion. Expect 2-4 days of emotional flatness, fatigue, reduced motivation, and disrupted sleep. Some users report that the comedown from 6-APB has a more "depressive" and less "anxious" character than MDMA's, but this varies. Plan recovery time accordingly and do not schedule demanding obligations for the 2-3 days following use.
Toxicity & Safety
5-HT2B Agonism and Cardiac Valvulopathy Risk
The most distinctive safety concern with 6-APB is its potent agonism at the 5-HT2B serotonin receptor. This receptor is richly expressed on cardiac valve interstitial cells, and chronic activation drives mitogenesis — excessive cell proliferation that leads to fibrotic thickening and dysfunction of heart valves . This is the exact mechanism through which fenfluramine (and its active metabolite norfenfluramine) caused the cardiac valvulopathy epidemic that led to its withdrawal from the market in 1997. Norfenfluramine displays high affinity at 5-HT2B (Ki = 10-50 nM), and 6-APB's measured affinity of 3.7 nM is even more potent .
The FDA has identified 5-HT2B as an explicit "anti-target" — a receptor that all new serotonergic medications must be screened against to prevent drug-induced cardiac valve fibrosis . While the fenfluramine cases involved chronic daily administration over months to years, the threshold exposure required to initiate valvulopathic changes remains unknown. Whether intermittent recreational use of 6-APB poses clinically meaningful cardiac risk is an open question with no human data to answer it.
Serotonin Syndrome Risk
As a potent serotonin releaser, 6-APB carries significant risk of serotonin syndrome when combined with other serotonergic agents, particularly MAOIs, SSRIs, SNRIs, and other serotonin releasers. Symptoms range from mild (tremor, agitation, diarrhea) to life-threatening (hyperthermia, seizures, cardiovascular collapse) .
Hyperthermia and Acute Toxicity
Like other serotonin-releasing empathogens, 6-APB can cause dangerous elevations in core body temperature. Reported fatalities associated with "Benzofury" products involved hyperthermia as a contributing factor, though polysubstance use was present in most documented cases. Between 2011 and 2012, ten deaths were identified at post-mortem with benzofury compounds, with the substance directly implicated in eight .
Limited Safety Data
A fundamental challenge in assessing 6-APB toxicity is the near-complete absence of controlled human studies. All safety data derives from case reports, forensic analyses, and animal models, making definitive risk assessment impossible.
References
Rothman RB et al. Evidence for possible involvement of 5-HT2B receptors in the cardiac valvulopathy associated with fenfluramine. Circulation. 2000;102(23):2836-2841. Rickli A et al. Pharmacological profile of novel psychoactive benzofurans. Br J Pharmacol. 2015;172(13):3412-3425. Huang XP et al. Serotonin receptors and heart valve disease — it was meant 2B. Pharmacol Ther. 2009;132(2):146-157. Boyer EW, Shannon M. The serotonin syndrome. N Engl J Med. 2005;352(11):1112-1120. ACMD. Benzofuran compounds report. Advisory Council on the Misuse of Drugs. UK Government. 2013.
Addiction Potential
Low to moderate addiction potential. 6-APB occupies an unusual position on the addiction liability spectrum because several of its pharmacological and experiential properties actively discourage compulsive use. The extremely slow onset (1-2 hours) eliminates the rapid reward signal that drives binge patterns with drugs like cocaine or mephedrone. The long duration (7-10 hours) means a single session is self-limiting -- there is no rapid cycling between peaks and crashes that compels redosing. And the serotonin-dominant pharmacology produces a heavy comedown that creates an aversive memory associated with recent use. That said, 6-APB does have reinforcing properties. Dopamine release contributes to the pleasurable, euphoric aspects of the experience, and the profound emotional warmth and perceptual beauty can create psychological attachment -- a desire to return to that state, particularly for individuals who find ordinary emotional experience flat or difficult. Tolerance to the empathogenic effects develops with repeated use and requires weeks to months to fully reset. Cross-tolerance exists with MDMA, MDA, and other serotonin-releasing empathogens. Physical dependence does not develop -- there is no withdrawal syndrome involving seizures or autonomic instability. The primary risk is not compulsive daily use (which the pharmacology and comedown actively prevent) but rather a pattern of increasingly frequent sessions spaced weeks rather than months apart, which compounds the 5-HT2B cardiac risk and cumulative serotonergic strain without producing the dramatic escalation pattern of classic stimulant addiction.
Overdose Information
Recognizing a 6-APB Emergency
6-APB overdose presents as a serotonergic and sympathomimetic toxicity syndrome, broadly similar to MDMA toxicity but with critical differences: the much slower onset (1-2 hours) means that double-dosing errors are common and the full toxic burden may not manifest until well after the point where intervention was possible; the longer duration (7-10+ hours) means the body sustains cardiovascular and thermoregulatory stress for a substantially longer period; and the 5-HT2B agonism introduces cardiac concerns not typically associated with acute MDMA toxicity.
Between 2011 and 2012, ten deaths were identified at post-mortem with benzofury compounds in the UK, with the substance directly implicated in eight.
Warning signs that demand immediate action:
- Extreme body temperature -- 6-APB is frequently reported as producing more intense hyperthermia than MDMA. If the person is burning hot to touch and has stopped sweating, thermoregulatory failure has occurred. This is the most immediately life-threatening complication
- Seizures -- any seizure activity requires emergency medical care
- Severe agitation or delirium -- the mild psychedelic component of 6-APB means high-dose emergencies can include visual disturbances and confusion beyond what typical stimulant toxicity produces
- Chest pain, palpitations, or irregular heartbeat -- 6-APB's cardiovascular effects are significant, and the long duration means the heart is under sustained strain. Cardiac arrhythmias have been documented
- Signs of serotonin syndrome -- the combination of high fever, muscle rigidity or clonus (rhythmic muscle jerking), tremor, agitation, confusion, and tachycardia. This is a medical emergency
- Loss of consciousness -- person cannot be roused
- Nausea and vomiting that will not stop -- especially concerning if the person is becoming drowsy, as aspiration is a risk
What to Do -- Step by Step
1. Call emergency services immediately. Call 911 (US), 999 (UK), 112 (EU), or your local emergency number. Tell them a benzofuran/empathogen has been taken. Good Samaritan protections apply in most jurisdictions.
2. Cool the person down. This is the highest-priority intervention after calling for help. Move to a cool environment. Remove excess clothing. Apply cool water to the neck, armpits, and groin. Fan continuously. Do not use ice water immersion without medical supervision.
3. Do not give more drugs. If the person redosed early (a common scenario with 6-APB due to the slow onset), the second dose may still be coming on. The clinical picture may worsen substantially over the next 1-2 hours. Communicate this to paramedics.
4. Manage psychological distress. The psychedelic component can produce frightening visual disturbances during a medical emergency. Speak calmly and steadily. Reduce stimulation. Do not restrain unless there is immediate danger.
5. Recovery position. If unconscious but breathing, place on their side. Monitor breathing until help arrives.
6. Inform paramedics thoroughly. Tell them 6-APB (a benzofuran empathogen, similar to MDMA) was taken, the approximate dose and timing of all doses, and any other substances involved. Emphasize the long duration -- medical staff familiar with MDMA may not expect symptoms to persist for 8-10+ hours.
Medical Treatment
Hospital management is supportive. Benzodiazepines for agitation and seizures. Active cooling for hyperthermia. IV fluids. Cyproheptadine for serotonin syndrome. Continuous cardiac monitoring -- particularly important with 6-APB given the 5-HT2B cardiac concerns, though acute valvulopathy from a single use has not been documented. The extended duration means clinical observation periods should be longer than for MDMA presentations. There is no specific antidote.
Dangerous Interactions
The combinations listed below may be life-threatening. Independent research should always be conducted to ensure safety when combining substances.
Extreme serotonin syndrome risk; potentially fatal — MAOIs massively potentiate MDMA
Extreme serotonin syndrome risk; potentially fatal — MAOIs massively potentiate MDMA
Tolerance
| Full | with prolonged and repeated use |
| Half | 3-4 weeks |
| Zero | 6-8 weeks |
Cross-tolerances
Legal Status
Australia and New Zealand: Certain countries contain a "substantially similar" catch-all clause in their drug law, such as New Zealand and Australia. This includes 6-APB as it is similar in chemical structure to the class A drug MDA, meaning 6-APB may be viewed as a controlled substance analogue in these jurisdictions.
Canada: 6-APB is Schedule III in Canada as it is an analogue of MDA. The CDSA was updated as a result of the Safe Streets Act changing amphetamines from Schedule 3 to Schedule 1.
Czech Republic: 6-APB is a Schedule I (List 4) substance. It may be used for research and restricted therapeutic purposes. (§ 1, d), 1. of Nařízení vlády č. 463/2013 Sb.)
France: 6-APB is classified as a narcotic since May 9, 2018, alongside other substances derived from benzofuran.
Germany: 6-APB is controlled under Anlage II BtMG (Narcotics Act, Schedule II) as of July 17, 2013. It is illegal to manufacture, possess, import, export, buy, sell, procure or dispense it without a license.
Italy: 6-APB is illegal in Italy.
Japan: 6-APB is a controlled substance in Japan effective December 17th, 2012.
Luxembourg:** 6-APB is not cited in the list of prohibited substances. Therefore, it is still a legal substance.
The Netherlands:** 6-APB is a controlled substance as of July 1, 2025.
Sweden: 6-APB is prohibited in Sweden as a "health hazard" as of 2009.
Switzerland: 6-APB is a controlled substance specifically named under Verzeichnis E.
Turkey:** 6-APB is a classed as drug and is illegal to possess, produce, supply, or import.
United Kingdom: On June 10, 2013, 6-APB and some analogues were classified as Temporary Class Drugs in the U.K. following an ACMD recommendation. On March 5, 2014, the U.K. Home Office announced that 6-APB would be made a class B drug on 10 June 2014 alongside every other benzofuran entactogen and many structurally related drugs.
United States: 6-APB is unscheduled in the United States, but not currently approved by the Food and Drug Administration for human consumption.
Responsible use
Research chemicals
Benzofuran
Entactogen
MDA
6-APB (Wikipedia)
6-APB (Erowid Vault)
6-APB (Isomer Design)
6-APB (Drugs-Forum)
MDMA Wiki
Discussion
The Big & Dandy 6-APB Thread (Bluelight)
Greene, S. L. (2013). Benzofurans and benzodifurans. In Novel Psychoactive Substances (pp. 383-392). https://doi.org/10.1016/B978-0-12-415816-0.00016-X
Experience Reports (3)
Tips (10)
6-APB has a potent affinity for the 5-HT2B receptor, which is linked to cardiac valve damage with chronic use. Treat it with the same spacing rules as MDMA: no more than once every 6-8 weeks minimum.
Start low with 6-APB and wait for full onset before redosing. Stimulant redosing extends duration and side effects more than it extends euphoria, while adding cardiovascular strain. Set a firm limit before you start.
6-APB fumarate salt requires higher doses than the HCl or succinate forms. For fumarate, a light to moderate experience is typically 80-120mg, while HCl may only need 60-90mg for comparable effects.
Do not take 6-APB in the afternoon or evening if you want to sleep that night. Most stimulants have long half-lives and even if you feel you can sleep, the quality will be significantly impaired.
Do not combine 6-APB with MAOIs or other serotonergic drugs. Many stimulants have serotonergic activity, and combinations can cause serotonin syndrome or hypertensive crisis, both medical emergencies.
Stay hydrated while using 6-APB. Stimulants increase heart rate and body temperature while suppressing thirst signals. Sip water regularly, roughly 250-500ml per hour, more if dancing or in hot environments.
Community Discussions (4)
Further Reading
See Also
Same Class
References (6)
- 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
- MDMA-assisted therapy for PTSD — Mithoefer et al. Psychopharmacology (2019)paper
- PubChem: 6-APB
PubChem compound page for 6-APB (CID: 9794343)
pubchem - 6-APB - TripSit Factsheet
TripSit factsheet for 6-APB
tripsit - 6-APB - Wikipedia
Wikipedia article on 6-APB
wikipedia