Harmine
Harmine (7-methoxy-1-methyl-β-carboline) is a naturally-occurring alkaloid of the β-carboline class. It is the principal monoamine oxidase-inhibiting component of ayahuasca, making DMT orally active. It blocks the enzyme that destroys serotonin and dietary tryptamines in the gut and liver.[1]
Harmine (7-methoxy-1-methyl-β-carboline) is a naturally-occurring alkaloid of the β-carboline class. It is the principal monoamine oxidase-inhibiting constituent of ayahuasca, distinguished by its role as a pharmacological enabler rather than a primary psychoactive agent. Harmine is a potent reversible inhibitor of MAO-A (MAO-A), producing its effects by preventing the enzymatic breakdown of serotonin and co-ingested tryptamines.[1]
Julius Fritzsche isolated harmine from Peganum harmala seeds in 1847[2] — a plant already used medicinally across the Middle East for thousands of years. In the 1920s, injectable harmine briefly treated Parkinson's disease before synthetic alternatives proved more reliable.[3] Today it is unscheduled in most countries and under preclinical investigation as a diabetes treatment.[4]
Subjective effects include mood elevation, enhanced introspection, and vivid visual imagery — though these are documented primarily in combination with DMT.[5] Harmine's standalone character is largely unknown — in most contexts it enables the experience rather than drives it. Nausea, vomiting, and a transient rise in blood pressure are the most consistently reported unsought effects.
No abuse liability has been established, and no controlled human dose data for harmine alone exist. The dominant risk is serotonin syndrome: combining harmine with antidepressants forces two serotonin-raising mechanisms at once, causing dangerous overheating, muscle rigidity, and seizure.[6] Most safety data come from ayahuasca studies rather than harmine alone, leaving its standalone risk profile incompletely characterized.
History[edit]
Discovery
Harmine was first isolated in 1847 by Julius Fritzsche from Peganum harmala seeds[2] — a plant with millennia of medicinal and ritual use across the Middle East and Central Asia. The same compound was later re-isolated from Banisteriopsis caapi in the 1920s under the names telepathine and banisterine before chemical analysis confirmed all three were identical.[7]
Clinical and scientific significance
In the late 1920s, Merck marketed injectable harmine as "banisterine" for Parkinson's disease. Clinical reports described improvement in roughly 80% of patients — reduced rigidity and elevated mood appearing within minutes of injection.[3] Tremor sometimes worsened, oral formulations proved ineffective, and synthetic anticholinergics replaced it by 1932.
Modern research trajectories
In 1984, McKenna, Towers, and Abbott demonstrated that harmine enables oral DMT psychoactivity by blocking first-pass MAO-A metabolism — the pharmacological basis of ayahuasca.[8] In 2015, researchers discovered harmine also drives insulin-producing pancreatic cells to proliferate via a separate enzyme-inhibiting mechanism.[4] By 2024, combination studies showed this approach could increase insulin-producing cell mass 4- to 7-fold in animal models.[9]
The name "harmine" derives from Harmala, the Latin genus name of its original plant source. The competing names — telepathine (from ethnographic reports of telepathic visions among indigenous ayahuasca users), banisterine (from Banisteriopsis), and yageine (from the Tucanoan yajé) — each carried the assumptions of their discoverers. The plant had been smoked, ingested, and burned as incense for thousands of years before a European chemist named its active constituent.
Chemistry[edit]
Structural class
Harmine belongs to the β-carboline family of alkaloids — a tricyclic ring system formed by fusing an indole to a pyridine ring.[10] Within the harmala series, harmine is the fully aromatic member; partial saturation shifts which targets the compounds prefer, with partially reduced harmaline showing greater affinity for serotonin receptors.[11]
Two substituents — a 1-methyl group and a 7-methoxy group — give harmine exceptional potency at MAO-A; removing either reduces binding tenfold or more.[1]
Molecular properties
| Molecular formula | C₁₃H₁₂N₂O |
| Molecular weight | 212.25 g/mol |
Harmine is a planar molecule with no stereoisomers — it exists in only one structural form and cannot be manufactured as a mirror-image variant.[12]
Pharmacology[edit]
Mechanism of action
MAO-A inhibition
Harmine is a potent, reversible inhibitor of MAO-A — the enzyme that breaks down serotonin and tryptamines in the gut and liver.[1] This inhibition enables oral DMT activity by preventing its first-pass destruction before it can reach the brain.[8] As a reversible inhibitor, dietary tyramine can displace harmine from the enzyme, substantially limiting the dangerous blood pressure spikes seen with older irreversible MAOI drugs[6] — but also capping harmine's maximum inhibitory effect.[13]
DYRK1A inhibition
Independently of MAO-A, harmine potently inhibits an enzyme called DYRK1A.[14] This drives insulin-producing pancreatic cells to proliferate[4] — a finding confirmed in subsequent studies and under active preclinical investigation as a diabetes treatment.[15] The same pathway also reduces the abnormal protein buildup linked to Alzheimer's disease and suppresses neuroinflammatory signaling.[16][17]
Pharmacokinetics
Harmine is broken down rapidly by liver enzymes (CYP2D6 and CYP1A2), leaving little reaching the bloodstream after oral dosing.[18] An intestinal transporter (MRP2) further limits absorption; blocking it roughly doubles oral bioavailability.[19] People who are genetically slow CYP2D6 metabolizers — or who take CYP2D6-inhibiting antidepressants such as fluoxetine or paroxetine — will have substantially higher harmine levels from equivalent doses.[18][20]
Neuroscience[edit]
Where it acts
In the ayahuasca context, neuroimaging shows increased activity in frontal and paralimbic regions during the acute state — areas associated with introspection, emotion, and visual processing.[21] Activity in the Default Mode Network — the set of brain regions most active during self-referential thinking — decreases significantly, particularly in the posterior cingulate cortex.[22] This pattern matches what is seen with psilocybin and is consistent with the intense introspective quality users report.
Why it matters
Harmine stimulates the growth and differentiation of neural stem cells in animal models[23] and restores depleted brain-support chemicals through a glial cell-dependent mechanism.[24] This distinguishes harmine from classical psychedelics, whose neuroplastic effects act primarily through serotonin receptors on neurons — harmine operates partly through support cells.
Whether harmine produces direct psychoactive effects at relevant doses is unknown — no controlled human study has tested it as a standalone agent. The antidepressant effects seen with ayahuasca[25] cannot be attributed to DMT alone, given harmine's independent neurogenic,[23] anti-inflammatory,[17] and glial-restorative[24] properties — but disentangling each component's contribution remains unresolved. Whether CYP2D6 genetic variation, which substantially alters harmine exposure,[18] affects therapeutic or adverse outcomes has not been studied.
Subjective Effects[edit]
In ayahuasca and pharmahuasca preparations, harmine's primary contribution is pharmacokinetic — it holds the enzymatic door open, permitting oral DMT activity rather than generating a distinct phenomenology of its own. Whether harmine produces any direct psychoactive effects at relevant oral doses remains an open question.[5]
Among reversible MAO-A inhibitors, harmine occupies unusual territory — mechanistically close to the antidepressant moclobemide, yet experientially embedded in the ayahuasca tradition. Unlike psilocybin or LSD, it has no reliably documented standalone psychedelic character. The experience in combination is shaped as much by set and setting as by pharmacology.
First isolated in 1847 from Peganum harmala seeds by Julius Fritzsche,[2] harmine saw brief clinical use for Parkinson's disease in the late 1920s before synthetic anticholinergics displaced it.[3] McKenna, Towers, and Abbott established its central pharmacological role in 1984, demonstrating that MAO-A inhibition enables oral DMT activity in ayahuasca.[4] It is now unscheduled in most jurisdictions and is an active preclinical candidate for diabetes treatment via a separate kinase-inhibiting mechanism.[5]
Subjective effects include mood elevation, enhanced introspection, nausea, and vivid visual imagery — though these are documented primarily in combination with DMT, which drives the primary phenomenology.[6] Harmine's standalone experiential character remains largely uncharacterized; historical clinical reports noted mood improvement at injectable doses, but no modern controlled study has assessed its isolated subjective effects. Nausea, vomiting, and transient blood pressure elevation are characteristic unsought effects.
No abuse liability has been established, and harmine's reversible MAO-A binding limits its pharmacodynamic ceiling compared to irreversible inhibitors.[7] The principal acute risk is serotonin syndrome when combined with serotonergic medications — a danger compounded in individuals with reduced CYP2D6 metabolism, who experience substantially higher systemic exposure.[8] No controlled human dose-response data for harmine alone have been published, representing the most significant gap in its safety characterization.
History[edit]
Discovery
Harmine was first isolated in 1847 by the German-Russian chemist Julius Fritzsche from the seeds of Peganum harmala, a plant with millennia of traditional use across the Middle East and Central Asia.[2] It was among the earliest alkaloids characterized from a psychoactive plant source. The compound was independently re-isolated from Banisteriopsis caapi under the names telepathine (by Guillermo Fischer-Cárdenas in 1923) and banisterine (by Louis Lewin in 1928), before chemical analysis confirmed all were identical to Fritzsche's harmine — a unification formally settled by 1939.[9]
Clinical and scientific significance
Following Lewin's characterization, Merck marketed injectable harmine as "banisterine" for postencephalitic Parkinsonism. Frank and Schlesinger reported improvement in roughly 80% of patients, with reduced rigidity and mood elevation appearing within minutes of subcutaneous injection.[3] The compound's clinical promise faded by 1932 — tremor sometimes worsened, oral formulations proved ineffective, and synthetic anticholinergics offered more reliable results.
Modern research trajectories
In 1984, McKenna, Towers, and Abbott published the foundational analysis demonstrating that harmine enables oral DMT psychoactivity by inhibiting first-pass MAO-A metabolism — the pharmacological mechanism underpinning ayahuasca.[4] A second major research line emerged in 2015 when Wang et al. discovered that harmine drives pancreatic β-cell proliferation via DYRK1A inhibition, opening a preclinical pipeline for diabetes therapeutics.[5] By 2024, combination studies showed harmine plus a GLP-1 receptor agonist could increase human β-cell mass 4- to 7-fold in animal models and reverse diabetes in xenograft studies.[10]
The name "harmine" derives from Harmala, the Latin-derived genus name of its original plant source. The competing names — telepathine (from ethnographic reports of telepathic visions among indigenous ayahuasca users), banisterine (from Banisteriopsis), and yageine (from the Tucanoan yajé) — each carried the cultural assumptions of their discoverers. The consolidation under "harmine" reflects priority of isolation rather than primacy of use; the plant had been smoked, ingested, and burned as incense for thousands of years before a European chemist gave its active constituent a name.
Chemistry[edit]
Structural class
Harmine belongs to the β-carboline family of indole alkaloids — a tricyclic ring system formed by an indole nucleus fused to a pyridine ring. Within the harmala alkaloid series, harmine is the fully aromatic member: harmaline is its partially reduced derivative, and tetrahydroharmine is the fully reduced form. The β-carboline scaffold is pharmacologically versatile, appearing across monoamine oxidase inhibitors, kinase inhibitors, and receptor ligands.[11]
Two substituents drive harmine's exceptional potency at MAO-A: the 1-methyl group on the pyridine ring and the 7-methoxy group on the indole ring. Removing either reduces MAO-A affinity by tenfold or more.[1] The degree of pyridine ring saturation shifts target selectivity — fully aromatic harmine favors MAO-A, while partially saturated harmaline retains greater affinity at serotonin 5-HT₂A/₂C receptors.[12]
Molecular properties
| Molecular formula | C₁₃H₁₂N₂O |
| Molecular weight | 212.25 g/mol |
The molecule is a planar, fully conjugated tricyclic system. The indole nitrogen bears a hydrogen that participates in hydrogen bonding and contributes to the compound's characteristic blue fluorescence under ultraviolet light. Harmine is achiral — the fully aromatic scaffold contains no stereogenic centers, and no stereoisomers exist.[13]
Physical properties
Harmine presents as a yellow crystalline solid with a melting point of approximately 261–262 °C.[13] It is poorly soluble in water, moderately soluble in ethanol, and stable under standard storage conditions.
Pharmacology[edit]
Mechanism of action
MAO-A inhibition
Harmine is a potent, reversible, and competitive inhibitor of MAO-A (MAO-A) — the enzyme responsible for breaking down serotonin, norepinephrine, and dietary tryptamines in the gut and liver. Among characterized β-carbolines, harmine binds MAO-A more tightly than any other member of the series.[1]
As a reversible inhibitor (RIMA), harmine differs fundamentally from irreversible MAOIs such as phenelzine and tranylcypromine. Dietary tyramine can competitively displace the reversible inhibitor from the enzyme, substantially limiting the dangerous blood pressure spikes ("cheese effect") associated with irreversible inhibitors.[7] This reversibility also means harmine may not achieve complete MAO-A inhibition, potentially capping its pharmacodynamic effect compared to irreversible MAOIs.[14]
The functional significance of this mechanism was established by McKenna, Towers, and Abbott, who demonstrated that harmine enables oral DMT psychoactivity by preventing first-pass MAO-A metabolism of DMT in the gut wall and liver.[4] This mechanism has been replicated and quantitatively modeled in subsequent studies.[6][15][16]
DYRK1A inhibition
Independently of its MAO-A activity, harmine potently inhibits the kinase DYRK1A.[17] Wang et al. demonstrated that this inhibition drives human pancreatic β-cell proliferation via the NFAT signaling pathway,[5] a finding confirmed by subsequent studies.[18] DYRK1A inhibition also reduces the abnormal protein phosphorylation implicated in Alzheimer's disease pathology[19][20] and suppresses neuroinflammatory pathways.[21]
Serotonin receptor activity
Harmine has modest affinity at serotonin 5-HT₂A and 5-HT₂C receptors, though substantially weaker than harmaline.[12] Whether this direct receptor activity contributes meaningfully to harmine's psychoactive profile in isolation remains unresolved.citation needed
Additional preclinical actions
Preclinical research has identified several further activities: stimulation of neural stem cell proliferation and differentiation,[22] restoration of BDNF levels and glutamate transporter expression in stress models via an astrocyte-dependent mechanism,[23] anti-inflammatory effects via TLR4/NF-κB pathway suppression,[21][24] and anticancer activity across multiple cell line and xenograft models.[25][26] All remain preclinical.
Pharmacokinetics
Harmine undergoes extensive first-pass metabolism in the liver, primarily converted to harmol by CYP2D6 and CYP1A2.[8] Oral bioavailability is low, explained by this rapid hepatic metabolism combined with intestinal efflux via the MRP2 transporter — inhibition of MRP2 roughly doubles oral bioavailability.[27]
Genetic variation in CYP2D6 substantially affects individual exposure: poor metabolizers (6–10% of European-ancestry populations) will have markedly higher harmine levels from equivalent doses.[8] CYP2D6 inhibitors such as fluoxetine and paroxetine produce a similar effect pharmacokinetically.[28]
In controlled ayahuasca studies, harmine plasma levels remained negligible relative to DMT, indicating a predominantly peripheral site of action sufficient to prevent DMT's first-pass metabolism.[6] Buccal co-administration of harmine (up to 180 mg) with DMT produced total subjective effect durations of 4–5 hours, with substantial interindividual variability in both clearance and bioavailability.[29][30]
Dedicated human pharmacokinetic studies of harmine in isolation have not been published. Specific values for oral bioavailability, volume of distribution, and half-life in humans are unavailable.
Neuroscience[edit]
Where it acts
In the ayahuasca context, neuroimaging reveals increased activation in frontal and paralimbic regions during the acute state, accompanied by enhanced introspective attention and intense emotional and visual imagery.[31] Palhano-Fontes et al. found significant reduction in Default Mode Network activity — particularly in the posterior cingulate cortex and medial prefrontal cortex — a pattern paralleling findings with psilocybin and consistent with the introspective phenomenology reported by users.[32]
Why it matters
Harmine stimulates neural stem cell proliferation, migration, and differentiation in animal models[22] and restores BDNF levels and glutamate transporter expression in stress models through an astrocyte-dependent mechanism.[23] This glial dimension distinguishes harmine from classical psychedelics whose neuroplastic effects are primarily mediated by serotonin receptors on cortical neurons. The Default Mode Network suppression observed under ayahuasca aligns with the REBUS model, which proposes that psychedelics loosen the brain's top-down filtering of information, enabling greater cognitive flexibility[32] — consistent with findings that ayahuasca enhances divergent thinking while decreasing convergent thinking.[33]
Whether harmine produces direct psychoactive effects at relevant doses remains unknown — no controlled human study has tested it as a standalone agent. Ayahuasca's antidepressant effects[34] cannot be attributed to DMT alone given harmine's independent neurogenic,[22] anti-inflammatory,[21] and astrocyte-restorative[23] properties, but disentangling each component's contribution remains unresolved.
Subjective Effects[edit]
Harmine's experiential profile is defined by what it enables rather than what it produces alone. As the monoamine oxidase-inhibiting component of ayahuasca and pharmahuasca preparations, its primary contribution is pharmacokinetic — permitting oral DMT activity rather than generating a distinct phenomenology of its own. Route of administration is decisive: oral harmine undergoes extensive first-pass metabolism yielding negligible brain levels, while injectable or buccal routes achieve higher exposure and may produce direct mood-elevating and mildly perceptual effects. Set and setting strongly modulate the qualitative character of the experience in combination preparations.[6]
Among reversible MAO-A inhibitors, harmine occupies a unique position — mechanistically closer to the antidepressant moclobemide but experientially associated with the ayahuasca tradition. Unlike classical psychedelics such as psilocybin or LSD, harmine's direct contribution to altered states of consciousness remains an open question, making it a compound defined more by what it enables in combination than by what it produces in isolation.
Effect Grid
At common doses, harmine produces significant MAO-A inhibition sufficient to enable oral DMT bioavailability in the ayahuasca context. As a standalone agent, effects may include moderate sedation, enhanced introspection, mild emotional enhancement, and subtle dreaming enhancement. Creativity enhancement and divergent thinking facilitation have been documented in the ayahuasca context at these dose ranges.
Physical effects typically include nausea (reported by most users in the ayahuasca context), bodily heaviness, mild dizziness, and possible trembling. Temperature dysregulation may occur. Gastrointestinal effects are the most consistently reported adverse response at this level.
Standalone psychoactive effects of harmine at common doses have not been characterized in controlled studies. All experiential descriptions are derived from the ayahuasca (harmine+DMT) combination context, where DMT drives the primary phenomenology.
Modeled from the effect's dose-dependence curve — not per-substance measurements.
Body high · Involuntary body movements · Stimulation · Vomiting · Nystagmus (eye wobbles)
Nystagmus (eye wobbles)
Timeline
Initial gastrointestinal awareness and nausea onset. Subtle somatic sensations emerge as MAO-A inhibition begins peripherally. Perceptual and cognitive baseline remains largely unchanged.
Rising perceptual and somatic effects with nausea peaking. Bodily heaviness, mild dizziness, and early emotional shifts become apparent. In ayahuasca context, DMT effects begin emerging as MAO-A inhibition enables oral bioavailability.
Maximum subjective intensity at approximately 60-120 minutes post-dose. Perceptual modifications, emotional intensification, introspection enhancement, and vivid visual imagery dominate. Nausea typically subsides but may persist.
Gradual return toward baseline over 2-4 hours. Perceptual effects diminish progressively while introspective quality and emotional openness may persist. Physical discomfort resolves.
Reflective, emotionally open state lasting 4-20 hours after primary effects resolve. Subtle mood elevation, enhanced introspection, and increased nature relatedness may persist.
⚠ Avoid driving or operating heavy machinery for at least 6 hours after ingestion.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Low
- Withdrawal
- None
- Tolerance buildup
- none
- Tolerance reset
- —
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- moclobemide
Toxicity
Acute toxicity
No controlled human dose-response data for harmine alone have been published. A provisional LD50 of 26.9 mg/kg has been cited in secondary sources, but the species, route, and primary source for this value are unverifiedsafety citation needed[26] — this figure should be treated as unreliable.
Gastrointestinal effects
Nausea and vomiting are the most consistently reported adverse effects in the ayahuasca context, typically transient and self-limiting.[27] These are especially common without dose standardization.[28]
Cardiovascular effects
Controlled studies documented a +9 mmHg increase in diastolic blood pressure at high ayahuasca doses.[5] This magnitude is modest but clinically relevant for people with pre-existing cardiovascular conditions.
Historical adverse effects
In 1920s–1930s Parkinson's trials, subcutaneous harmine (20–70 mg) sometimes worsened tremor — a finding that contributed to its clinical abandonment.[3]
Psychological risks
No published data characterize harmine-specific psychological risks in isolation. In the ayahuasca context, high doses can produce overwhelming experiences, confusion, and anxiety[28] — and people with pre-existing psychiatric diagnoses report adverse effects more frequently.[27]
As a reversible MAO-A inhibitor without strong direct serotonin-receptor activation, harmine's standalone psychological risk profile is expected to differ substantially from classical psychedelics — but this is inference rather than established fact.inferred
Tolerance & dependence
No controlled studies characterize tolerance development, dependence, or withdrawal specific to harmine. No withdrawal syndrome has been described.
Related β-carbolines are normal human metabolites,[29] and elevated levels have been found in people with heroin dependence and alcohol use disorder[30] — though whether this is cause or effect is unknown. Dependence potential is inferred as low based on harmine's reversible mechanism, not substance-specific data.inferred
Drug Interactions
Serotonergic medications
Combining any MAO-A inhibitor with serotonin-raising antidepressants — SSRIs, SNRIs, tricyclics — risks serotonin syndrome: a dangerous state of serotonin overload causing overheating, muscle rigidity, rapid heartbeat, and seizure.[6] CYP2D6-inhibiting antidepressants such as fluoxetine and paroxetine compound this risk by simultaneously raising harmine blood levels and adding serotonergic load.[20] Available data remain insufficient to fully characterize this synergistic risk.[31]
Tryptamine compounds
Harmine dramatically increases the bioavailability of orally administered tryptamines — DMT, 5-MeO-DMT, psilocybin — by blocking their first-pass metabolism.[8][5] Doses that are safe in isolation become dangerous in combination. Precise dose titration is essential.
Tyramine-containing foods
Because harmine is a reversible inhibitor, dietary tyramine can displace it from the enzyme, substantially reducing the dangerous blood pressure response associated with older irreversible MAOI drugs.[6] Caution with high-tyramine foods (aged cheese, cured meats, fermented foods) remains advisable at doses producing significant MAO-A inhibition.
CYP2D6 inhibitors
CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine) and CYP2D6 poor metabolizer genotype reduce harmine clearance, increasing systemic exposure and extending the duration of MAO-A inhibition.[18][20]
MRP2 inhibitors
MRP2 inhibitors such as probenecid increase harmine's oral bioavailability approximately 1.96-fold.[19]
Contraindications
9 knownConcurrent SSRI/SNRI use: Serotonin syndrome risk from combined MAO-A inhibition and serotonin reuptake inhibitor. Absolute contraindication. A washout period appropriate to the SSRI's half-life is required before harmine administration.[20]
Concurrent irreversible MAOI use: Additive MAO-A inhibition exceeding the reversible ceiling. Absolute contraindication. A washout period of at least two weeks is required.[6]
Concurrent tryptamine use without precise dose titration: Harmine dramatically increases tryptamine bioavailability, making unpredictable potentiation dangerous without careful dosing.[8]
Cardiovascular instability: Dose-dependent blood pressure elevation contraindicates use in uncontrolled hypertension or significant heart conditions.[5]
Liver impairment: Reduced liver enzyme capacity may substantially increase harmine exposure.[18]
CYP2D6 poor metabolizer status: Genetically poor metabolizers (6–10% of European-ancestry populations) will have substantially elevated harmine levels, increasing the magnitude and duration of MAO-A inhibition. Relative contraindication requiring dose adjustment.[18]
Pregnancy and lactation: No reproductive safety data are available.citation needed
Harm Reduction[edit]
Forms & Identification
Harmine circulates as raw Peganum harmala seeds, crude plant extracts, purified freebase powder (yellow crystalline), hydrochloride salt (white to off-white powder), and as a component of ayahuasca brews and pharmahuasca preparations. The freebase fluoresces bright blue under ultraviolet light — a useful but not definitive field identification marker.
Alkaloid content in raw seeds and brews varies substantially between batches. Quantitative analysis is the only reliable way to determine potency. Purified harmine should be verified against a known reference standard whenever possible.
Guidelines
- Test all purified material with reagent kits before use; confirm identity if possible
- Start with the lowest effective dose, especially with unfamiliar batches or preparations
- Do not combine with serotonergic medications (SSRIs, SNRIs, tricyclics) — allow a full washout period
- Avoid high-tyramine foods (aged cheese, cured meats, fermented foods) for 12–24 hours before and after use
- Have a sober sitter present, particularly for combination preparations
- Keep sessions in a safe, comfortable environment with easy access to a bathroom
- Do not operate vehicles or machinery during and for several hours after use
- Individuals with heart conditions, liver impairment, or who are CYP2D6 poor metabolizers should exercise particular caution or avoid use
Set & Setting
In ayahuasca or pharmahuasca preparations, psychological state and environment shape the experience significantly. A calm, familiar setting with a trusted sitter present reduces risk. Nausea and vomiting are common — having water, a bucket, and a comfortable place to lie down prepared in advance reduces distress.
First experiences should be approached at conservative doses in a low-stimulus environment.
Aftercare & integration. After ayahuasca or pharmahuasca experiences, allow time for physical and psychological recovery. Rehydrate and eat light, easily digestible food when appetite returns. Nausea and fatigue may persist for several hours after the primary effects subside.
Emotionally intense material may surface during the experience. Journaling, quiet reflection, and conversation with trusted companions can support processing. If distressing thoughts or emotional difficulty persist beyond a few days, seek support from a mental health professional experienced with psychedelic experiences.
Recovery & Support
Harmine does not produce physical dependence, and compulsive patterns of use are not documented in the clinical literature. If harmine or ayahuasca use has become a source of concern — interfering with relationships, responsibilities, or wellbeing — peer support communities and psychedelic integration therapists can provide non-judgmental guidance. For broader substance use concerns, SAMHSA's National Helpline (1-800-662-4357) offers free, confidential referrals.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Most adverse reactions to harmine and harmala-containing preparations are uncomfortable but not life-threatening — nausea, vomiting, anxiety, and elevated blood pressure. The primary emergency concern is serotonin syndrome, which occurs when harmine is combined with serotonergic medications.
Recognizing an emergency:
- Agitation, confusion, or rapid mood changes beyond what the dose would explain
- Muscle rigidity, twitching, or tremors
- Rapid heartbeat, high fever, or profuse sweating
- Seizure or loss of consciousness
Immediate steps:
- 1. Move the person to a cool, quiet environment
- 2. Remove excess clothing if body temperature is elevated
- 3. Do not restrain unless there is immediate danger of self-harm
- 4. Call emergency services if symptoms include high fever, seizure, muscle rigidity, or loss of consciousness
- 5. Place an unconscious person in the recovery position
What to tell the dispatcher: Name the substance (harmine, harmala, or ayahuasca), approximate amount and time of ingestion, whether any other substances or medications were taken, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help.
Legal Status[edit]
Harmine is not scheduled under the United Nations Convention on Psychotropic Substances and does not appear on any INCB international control lists.[32] Most countries do not specifically schedule the compound, though status varies by jurisdiction.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Unscheduled (federally) | Not listed in DEA Controlled Substances schedules. USDA restricts Peganum harmala importation in six western states as a noxious invasive weed.[32] |
| Canada | Schedule III (CDSA) | Listed as item 9 under Schedule III of the Controlled Drugs and Substances Act.[32] |
| Australia | Prohibited | Import and export prohibited under the Customs Act 1901. Consumption prohibited under most state and territory legislation.[32] |
| France | Prohibited | Classified as a poisonous plant; sale and distribution prohibited under the French Public Health Code.[32] |
| United Kingdom | Not confirmed | Not specifically identified as a controlled substance in available sources. Verification against the Misuse of Drugs Act 1971 is recommended.citation needed |
| Germany / EU | Not confirmed | No specific EU-wide scheduling identified. Not listed on UN schedules. |
| United Nations | Not scheduled | Not listed on INCB Yellow, Green, or Red Lists.[32] |
In the United States, while harmine itself is unscheduled, ayahuasca preparations containing DMT are controlled under the Controlled Substances Act (DMT is Schedule I). The Supreme Court ruled in Gonzales v. O Centro Espirita Beneficente Uniao do Vegetal (2006) that the Religious Freedom Restoration Act protects sacramental ayahuasca use for specific religious groups, but this ruling does not decriminalize the compound generally.citation needed
Legal status changes frequently and varies by jurisdiction. This information is not legal advice. Verify current local law before purchasing, possessing, or transporting any harmine-containing material.
Safety[edit]
- Acute toxicity
- Low
- Chronic toxicity
- Low
- Withdrawal
- None
- Tolerance buildup
- none
- Tolerance reset
- —
- Physical
- None
- Psychological
- Negligible
- Compulsive redosing
- Negligible
- Dose escalation
- Negligible
- Cross-tol.
- moclobemide
Toxicity
Acute toxicity
An LD50 of 26.9 mg/kg has been cited in secondary sources, but the species, route of administration, and primary source for this value are unverified.safety citation needed[35] This value should be treated as provisional. No controlled human dose-response data for harmine alone have been published.
In preclinical cancer studies, harmine did not produce toxic effects in major organs at doses sufficient for antitumor activity in mice.[25]
Gastrointestinal effects
Nausea and vomiting are the most consistently reported adverse effects in the ayahuasca context, typically transient and self-limiting.[36] Traditional ayahuasca use is "often accompanied by distressing effects like nausea, vomiting, and intense hallucinations, possibly due to complex PK/PD interactions and lack of dose standardization".[37]
Cardiovascular effects
Controlled studies documented a +9 mmHg increase in diastolic blood pressure at the high ayahuasca dose.[6] The magnitude is modest but clinically relevant for individuals with pre-existing cardiovascular conditions.
Historical adverse effects
In 1920s–1930s Parkinson's disease trials, subcutaneous harmine (20–70 mg) sometimes worsened tremor — a finding that contributed to its clinical abandonment.[3]
Psychological risks
No published data characterize harmine-specific psychological risks at psychoactive doses in isolation. In the ayahuasca context, high doses can produce overwhelming experiences, confusion, and anxiety.[37] Users with pre-existing psychiatric diagnoses report adverse effects more frequently.[36]
The risk of psychosis, persistent perceptual changes, or lasting psychiatric destabilization from harmine alone has not been assessed. As a reversible MAO-A inhibitor without strong direct 5-HT₂A agonism, harmine's standalone psychological risk profile is expected to differ substantially from classical psychedelics, but this is inference rather than established fact.inferred
Tolerance & dependence
No published controlled studies characterize tolerance development, abuse liability, or withdrawal phenomena specific to harmine. No withdrawal syndrome has been described.
Related β-carbolines norharman and harman are normal endogenous metabolites,[38] and elevated levels have been found in heroin-dependent and alcoholic patients, though directionality and causality remain unclear.[39]
Given harmine's reversible MAO-A inhibition, dependence potential is inferred as low compared to monoaminergic stimulants. This assessment is based on pharmacological mechanism, not substance-specific dependence data.inferred
Drug Interactions
Harmine's interactions are governed by its MAO-A inhibition (pharmacodynamic) and its metabolism by CYP2D6 and CYP1A2 (pharmacokinetic).
Serotonergic medications
Combining any MAO-A inhibitor — including reversible inhibitors — with serotonergic agents (SSRIs, SNRIs, tricyclic antidepressants) creates risk of serotonin syndrome. CYP2D6-inhibiting antidepressants such as fluoxetine and paroxetine compound this risk by simultaneously increasing harmine systemic exposure and adding serotonergic load.[28] The reversible nature of harmine's MAO-A inhibition reduces but does not eliminate serotonin syndrome risk.[7]
Available pharmacological interaction data for ayahuasca combinations remain "insufficient to determine synergistic risk".[16]
Tryptamine compounds
Harmine dramatically potentiates orally administered tryptamines (DMT, 5-MeO-DMT, psilocybin) by inhibiting their first-pass metabolism.[4][6] This is the pharmacological basis of ayahuasca. Doses safe in isolation become dangerous when combined; precise dose titration is essential.
Tyramine-containing foods
The hypertensive "cheese effect" is less severe with reversible MAO-A inhibitors because dietary tyramine can competitively displace the inhibitor from the enzyme.[7] Caution with high-tyramine foods remains advisable at doses producing significant MAO-A inhibition.
CYP2D6 inhibitors
CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine) and CYP2D6 poor metabolizer genotype reduce harmine clearance, increasing systemic exposure and the magnitude of MAO-A inhibition.[8][28]
MRP2 inhibitors
MRP2 inhibitors (probenecid) increase harmine oral bioavailability approximately 1.96-fold.[27]
Contraindications
9 knownConcurrent SSRI/SNRI use: Serotonin syndrome risk from combined MAO-A inhibition and serotonin reuptake inhibitor. Absolute contraindication. A washout period appropriate to the SSRI's half-life is required before harmine administration.[28]
Concurrent irreversible MAOI use: Additive MAO-A inhibition exceeding the reversible ceiling. Absolute contraindication. A washout period of at least two weeks is required.[7]
Concurrent tryptamine use without precise dose titration: Harmine dramatically increases tryptamine bioavailability, making unpredictable potentiation dangerous without careful dosing.[4]
Cardiovascular instability: Dose-dependent blood pressure elevation contraindicates use in uncontrolled high blood pressure or significant heart conditions.[6]
Liver impairment: Reduced liver enzyme capacity may substantially increase harmine exposure.[8]
CYP2D6 poor metabolizer status: Genetically poor metabolizers (6–10% of European-ancestry populations) will have substantially elevated harmine levels, increasing the magnitude and duration of MAO-A inhibition. Relative contraindication requiring dose adjustment.[8]
Pregnancy and lactation: No reproductive safety data are available.citation needed
Harm Reduction[edit]
Forms & Identification
Harmine circulates as raw Peganum harmala seeds, crude plant extracts, purified freebase powder (yellow crystalline), hydrochloride salt (white to off-white powder), and as a component of ayahuasca brews and pharmahuasca preparations. The freebase fluoresces bright blue under ultraviolet light — a useful but not definitive field identification marker. Alkaloid content in raw seeds and brews varies substantially between batches; quantitative analysis is the only reliable way to determine potency. Purified harmine should be verified against a known reference standard whenever possible.
Guidelines
- Test all purified material with reagent kits before use; confirm identity if possible
- Start with the lowest effective dose, especially with unfamiliar batches or preparations
- Do not combine with serotonergic medications (SSRIs, SNRIs, tricyclics) — allow a full washout period
- Avoid high-tyramine foods (aged cheese, cured meats, fermented foods) for 12–24 hours before and after use
- Have a sober sitter present, particularly for combination preparations
- Keep sessions in a safe, comfortable environment with easy access to a bathroom
- Do not operate vehicles or machinery during and for several hours after use
- Individuals with heart conditions, liver impairment, or who are CYP2D6 poor metabolizers should exercise particular caution or avoid use
Set & Setting
When used as part of ayahuasca or pharmahuasca preparations, the experience is shaped substantially by psychological state and environment. A calm, familiar setting with a trusted sitter is recommended. Nausea and vomiting are common — having water, a bucket, and a comfortable place to lie down prepared in advance reduces distress. First experiences should be approached at conservative doses in a low-stimulus environment.
Aftercare & integration. After ayahuasca or pharmahuasca experiences, allow time for physical and psychological recovery. Rehydrate and eat light, easily digestible food when appetite returns. Nausea and fatigue may persist for several hours after the primary effects subside.
Emotionally intense material may surface during the experience. Journaling, quiet reflection, and conversation with trusted companions can support processing. If distressing thoughts or emotional difficulty persist beyond a few days, seek support from a mental health professional experienced with psychedelic experiences.
Recovery & Support
Harmine does not produce physical dependence, and compulsive patterns of use are not documented in the clinical literature. If harmine or ayahuasca use has become a source of concern — interfering with relationships, responsibilities, or wellbeing — peer support communities and psychedelic integration therapists can provide non-judgmental guidance. For broader substance use concerns, SAMHSA's National Helpline (1-800-662-4357) offers free, confidential referrals.
Recovery resources, crisis lines, and support pathways → View all
Emergency Response
Most adverse reactions to harmine and harmala-containing preparations are uncomfortable but not life-threatening — nausea, vomiting, anxiety, and elevated blood pressure. The primary emergency concern is serotonin syndrome, which occurs when harmine is combined with serotonergic medications.
Recognizing an emergency:
- Agitation, confusion, or rapid mood changes beyond what the dose would explain
- Muscle rigidity, twitching, or tremors
- Rapid heartbeat, high fever, or profuse sweating
- Seizure or loss of consciousness
Immediate steps:
- 1. Move the person to a cool, quiet environment
- 2. Remove excess clothing if body temperature is elevated
- 3. Do not restrain unless there is immediate danger of self-harm
- 4. Call emergency services if symptoms include high fever, seizure, muscle rigidity, or loss of consciousness
- 5. Place an unconscious person in the recovery position
What to tell the dispatcher: Name the substance (harmine, harmala, or ayahuasca), approximate amount and time of ingestion, whether any other substances or medications were taken, and current symptoms. Good Samaritan laws in many jurisdictions protect people who call for help.
Legal Status[edit]
Harmine is not scheduled under the United Nations Convention on Psychotropic Substances and does not appear on any INCB international control lists.[40] Legal status varies by jurisdiction, with most countries not specifically scheduling the compound.
| Jurisdiction | Classification | Key provisions |
|---|---|---|
| United States | Unscheduled (federally) | Not listed in DEA Controlled Substances schedules. USDA restricts Peganum harmala importation in six western states as a noxious invasive weed.[40] |
| Canada | Schedule III (CDSA) | Listed as item 9 under Schedule III of the Controlled Drugs and Substances Act.[40] |
| Australia | Prohibited | Import and export prohibited under the Customs Act 1901. Consumption prohibited under most state and territory legislation.[40] |
| France | Prohibited | Classified as a poisonous plant; sale and distribution prohibited under the French Public Health Code.[40] |
| United Kingdom | Not confirmed | Not specifically identified as a controlled substance in available sources. Verification against the Misuse of Drugs Act 1971 is recommended.citation needed |
| Germany / EU | Not confirmed | No specific EU-wide scheduling identified. Not listed on UN schedules. |
| United Nations | Not scheduled | Not listed on INCB Yellow, Green, or Red Lists.[40] |
In the United States, while harmine itself is unscheduled, ayahuasca preparations containing DMT are controlled under the Controlled Substances Act (DMT is Schedule I). The Supreme Court ruled in Gonzales v. O Centro Espirita Beneficente Uniao do Vegetal (2006) that the Religious Freedom Restoration Act protects sacramental ayahuasca use for specific religious groups, but this ruling does not decriminalize the compound generally.citation needed
Frequently asked questions
What is Harmine?
Harmine is a β-carboline alkaloid and reversible inhibitor of monoamine oxidase A (RIMA) found in Peganum harmala and Banisteriopsis caapi. It serves as the principal pharmacological enabler of oral DMT activity in ayahuasca and is under preclinical study as a DYRK1A inhibitor for diabetes.
How long does Harmine last?
Total duration by route of administration — Oral: 4 – 6 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 Harmine?
Psychedex publishes a dosage table for Harmine on this page covering these routes of administration: oral, buccal. Dose values are presented only in that table, always alongside their route of administration.
What are dangerous combinations with Harmine?
The highest-severity documented interactions for Harmine: Amphetamines (Lethal), MDMA, Amphetamines (Lethal), MDMA, MDA (Lethal), Psychedelics (Lethal), SNRIs (Lethal). See the interactions section for the full list with mechanisms and severity levels.
Is Harmine addictive?
Psychedex records tolerance and dependence data rather than a yes/no rating. Recorded tolerance indicators for Harmine: tolerance builds none; cross-tolerance develops with moclobemide. 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.
references
- [1] ^abcKim H, Sablin SO, Ramsay RR (1997) Inhibition of monoamine oxidase A by beta-carboline derivatives — Archives of Biochemistry and Biophysics PMID:8990278
- [2] ^abPatel K, Gadewar M, Tripathi R, Prasad SK, Patel DK (2012) A review on medicinal importance, pharmacological activity and bioanalytical aspects of beta-carboline alkaloid Harmine — Asian Pacific Journal of Tropical Biomedicine doi:10.1016/s2221-1691(12)60116-6
- [3]
- [4] ^abcWang P, Alvarez-Perez JC, Felsenfeld DP, Liu H, Sivendran S, et al. (2015) A high-throughput chemical screen reveals that harmine-mediated inhibition of DYRK1A increases human pancreatic beta cell replication — Nature Medicine doi:10.1038/nm.3820
- [5]
- [6]
references
- [1] ^abcKim H, Sablin SO, Ramsay RR (1997) Inhibition of monoamine oxidase A by beta-carboline derivatives — Archives of Biochemistry and Biophysics PMID:8990278
- [2] ^abPatel K, Gadewar M, Tripathi R, Prasad SK, Patel DK (2012) A review on medicinal importance, pharmacological activity and bioanalytical aspects of beta-carboline alkaloid Harmine — Asian Pacific Journal of Tropical Biomedicine doi:10.1016/s2221-1691(12)60116-6
- [3]
- [4]
- [5] ^abcWang P, Alvarez-Perez JC, Felsenfeld DP, Liu H, Sivendran S, et al. (2015) A high-throughput chemical screen reveals that harmine-mediated inhibition of DYRK1A increases human pancreatic beta cell replication — Nature Medicine doi:10.1038/nm.3820
- [6]