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Australian Institute of Pharmacognosy

Australian Research & Education

Syrian Rue (Peganum harmala): Sacred Smoke, Serious Risks

Dr Thomas Ridley

By Dr Thomas Ridley · Australian Institute of Pharmacognosy

Head of Education and Research

39 min read

Fruiting Syrian rue with orange seed capsules

AIP Monograph No. 2 · Plant profileSyrian rueSacred smoke, serious chemistry: Peganum harmala and the evidenceBy Dr Thomas Ridley · Australian Institute of Pharmacognosy · September 2026 · 29 min read

Cover: fruiting harmal, Bukhara region, Uzbekistan. Photo: Humoyun Mehridinov · CC BY-SA 4.0 · Wikimedia Commons

In Iran, Turkey and the Maghreb, dark seeds crackle on hot charcoal and the smoke is passed over newborns and brides to keep the evil eye away. Traditional The same seeds turn up in medical case reports of fatal poisoning (PMID 34401132). Confirmed Syrian rue lives both lives at once, and this article is about telling them apart.

Burnt as esfand against the evil eye from Morocco to Xinjiang, and one of the richest readily available botanical sources of the β-carboline alkaloids, Syrian rue is a plant whose cultural life is larger than its medical one, and whose pharmacology is more serious than its reputation. This is No. 2 in the Australian Institute of Pharmacognosy’s evidence-graded monograph series: what is traditional, what is preclinical, what has actually been shown in people, and what Australian law says.

This article is educational. It is not medical advice, and nothing in it is a recommendation to obtain, prepare or use Peganum harmala or its alkaloids.

Before you read further — two hard facts

1. Legal status in Australia. Harmala alkaloids are Schedule 9 (Prohibited Substance) in the Poisons Standard, with two narrow exemptions: herbs or preparations for therapeutic use containing 0.1% or less of harmala alkaloids, or divided preparations containing 2 mg or less of harmala alkaloids per recommended daily dose. Dry P. harmala seed has been measured at 4.3% harmine and 5.6% harmaline (w/w) (Herraiz 2010, PMID 20036304) — around a hundredfold above the 0.1% exemption threshold. On the Institute’s reading of the entry, raw seed and any meaningful extract fall outside both exemptions and are captured by Schedule 9. Confirmed — Poisons Standard, Schedule 9, entry “HARMALA ALKALOIDS”; DMT is separately listed in Schedule 9. In Queensland, harmaline, harmalol and DMT are also dangerous drugs under Schedule 2 of the Drugs Misuse Regulation 1987 (Qld), and the Drugs Misuse Act 1986 (Qld) defines a dangerous drug to include a listed substance contained in a natural substance, such as seed. Possessing, producing (which includes cultivating) or supplying a dangerous drug without authority is a serious criminal offence. These instruments are amended regularly, so check the current Queensland legislation and the current Poisons Standard via the TGA before relying on this summary.

2. Pharmacological hazard. Harmine and harmaline are potent reversible MAO-A inhibitors. Anything that raises serotonin or depends on MAO-A for clearance is a real interaction risk: SSRIs/SNRIs, triptans, tramadol, pethidine, dextromethorphan, St John’s wort, 5-HTP, and sympathomimetic decongestants. Tyramine-rich foods matter less with a reversible inhibitor than with an irreversible one, but a crude seed extract is not a measured dose. Fatal human poisonings are documented. See §8.

If someone is unwell after taking harmal: call Triple Zero (000) in an emergency, or the Poisons Information Centre on 13 11 26 (24 hours, Australia-wide).

At a glance

The plant Peganum harmala L. (Nitrariaceae): Syrian rue, harmal, esfand. A perennial of arid country, naturalised in Australia and treated as an agricultural weed. Evidence suggests §1, §5
Traditional role Burnt as incense against the evil eye from Morocco to Xinjiang, and a “hot” drug in Persian and Arabic medicine. Traditional §2–§4
Chemistry Dry seed measured at 5.6% harmaline and 4.3% harmine (w/w), roughly 10% MAO-A-inhibiting alkaloid by mass (PMID 20036304). Confirmed §7
Main action A potent, reversible inhibitor of the enzyme MAO-A (PMID 20036304). Confirmed §8.1
Evidence in people No controlled clinical trial of the plant for any therapeutic use has been found. The human studies that do exist test isolated harmine given with DMT to healthy volunteers (PMIDs 38089057, 39774840, 39923404). Confirmed §9, §11
Most active research Isolated harmine (not the herb) as a DYRK1A inhibitor for human β-cell regeneration. Preclinical only (PMID 38985854). Evidence suggests §8.2
Main dangers Serious interactions with serotonergic and other medicines, and documented fatal poisonings, including in pregnancy (PMID 34401132). Confirmed §8.1, §8.5
Australian law Harmala alkaloids are Schedule 9 (Prohibited Substance), with two narrow exemptions. In Queensland, harmaline and harmalol are also scheduled dangerous drugs. See the box above. Confirmed
How to read the evidence tags in this article. Every substantive claim carries one:

  • Confirmed — established in humans by trial or by unambiguous analytical/chemical fact.
  • Evidence suggests — real published data, but preclinical, observational, small, or not yet replicated in humans.
  • Mechanism — a plausible mechanistic or pharmacological inference, not an outcome.
  • Traditional — historical, ethnobotanical or ritual use. Evidence of practice, not of efficacy.

Every PubMed ID (PMID) links to its PubMed record and was checked against PubMed in September 2026; every chemical record was checked against PubChem. Where a claim is widely repeated but I could not trace it to a primary source, it is marked unsourced and left as such.

The short version

Peganum harmala L. (Nitrariaceae; long placed in Zygophyllaceae) is a perennial of arid steppe from the eastern Mediterranean to Central Asia and north-west India, naturalised as a serious rangeland weed in North America, southern Africa and Australia. It is simultaneously one of the most culturally embedded plants of the Persianate and Islamic world — burnt as esfand against the evil eye — and one of the most pharmacologically consequential, because its seeds are the densest readily available botanical source of the β-carboline alkaloids harmine, harmaline and harmalol.

Three distinct pharmacologies live in one plant, and conflating them is the commonest error in the literature.

  • (i) The β-carbolines are reversible MAO-A inhibitors — the basis of the plant’s psychoactivity, its entire interaction profile, and its role as the MAOI half of ayahuasca analogues.
  • (ii) Harmine is also a potent DYRK1A inhibitor, which is a wholly separate and currently the most translationally serious line of work on the compound: it is the lead scaffold in human β-cell regeneration for diabetes.
  • (iii) The aerial parts carry quinazoline alkaloids (vasicine, vasicinone, deoxyvasicine) with bronchodilator and expectorant activity that has nothing to do with MAO at all.

Human clinical evidence for therapeutic use of the whole plant is, at the time of writing, effectively absent.

What exists in humans is controlled pharmacokinetic and pharmacodynamic work on isolated harmine co-administered with DMT. Everything else — antidiabetic, antileishmanial, anti-inflammatory, hepatoprotective, anticancer — is preclinical. That gap between a very large preclinical literature and a very small clinical one is the single most important thing to hold in mind when reading about this plant.

Peganum harmala in bud in its native range, Syria.
Peganum harmala in bud in its native range, Syria. Photo: Anas A. Emad · CC BY-SA 4.0 · Wikimedia Commons

Chapter 1What it’s called: names and taxonomy

Field Detail
Accepted name Peganum harmala L., Sp. Pl. 1: 444 (1753)
Family Nitrariaceae under APG IV. Most of the pharmacological literature, including the standard reviews, still writes Zygophyllaceae — that is the older placement, not an error of identification. Expect both in the literature; this article uses Nitrariaceae.
Genus Peganum L. — small genus of arid-zone perennials; P. nigellastrum and P. multisectum are the species most often confused with it in Chinese and Central Asian material.
English Syrian rue, wild rue, harmal; African rue and Mexican rue in North America (the weed-science names); Turkish rue — see the dye note in §7.
Persian esfand / espand (اسفند), also sipand, berg-e esfand for the seed capsules burnt as incense.
Arabic harmal / harmel (حرمل) — the root of every alkaloid name in §7.
Turkish üzerlik (üzerlik otu) — the strung seed-capsule charm is nazarlık.
Urdu / Hindi isband, hurmal, harmal.
Chinese 骆驼蓬 (luò tuo péng) — “camel bush”; used in Uyghur medicine, where it is yüzerlik.
Berber / Maghreb harmel, bendeqouq (regional).

A naming caution that matters clinically. “Rue” in English normally means Ruta graveolens (Rutaceae) — a different plant, different chemistry (furanocoumarins, rutin), different toxicity. Peganum is not related to it. Any historical source that says “rue” without a binomial is ambiguous, and a good deal of loose internet material silently merges the two. Confirmed

Harmal on dry steppe in Altyn-Emel National Park, Kazakhstan.
Harmal on dry steppe in Altyn-Emel National Park, Kazakhstan. Photo: Nikolai Bulykin · CC BY-SA 4.0 · Wikimedia Commons

Chapter 2Where it comes from: history and origin

The species is native to the arid and semi-arid belt running from the eastern Mediterranean and North Africa through Iran and the Central Asian steppe to north-west India, on saline, sandy and disturbed soils that suit almost nothing else. Confirmed

It has been introduced and has naturalised in the Americas (where it arrived in the early twentieth century, reportedly as a dye plant in New Mexico — a frequently repeated origin story I could not trace to a primary source, so treat it as unsourced), in southern Africa, and in Australia (§5).

Its documentary history is unusually deep. Harmal appears across the classical Greco-Arabic and Persian materia medica — Dioscorides’ moly/peganon agrion is conventionally identified with it, and it runs continuously through Avicenna’s Canon, al-Razi, and later the Indo-Persian Makhzan al-Adwiya — as a “hot” drug for “cold” conditions: joint pain, colic, worms, amenorrhoea and menstrual obstruction. Traditional

One gap is worth flagging honestly: I have not been able to locate a classical text that prescribes harmal specifically for hemicrania (shaqīqa), despite the classical literature discussing shaqīqa at length. Until the primary Persian and Arabic sources are read closely, the “traditional use for migraine” claim is unsourced.

Archaeologically, the plant now has a hard data point in the psychoactive record: multi-analytical work on a Ptolemaic Egyptian Bes vase reported residues consistent with Peganum harmala alongside other psychotropic constituents (PMID 39537764). Evidence suggests — residue analysis, single vessel, so it evidences presence, not a defined ritual practice.

A nazar glass bead in Cappadocia, Turkey: the best-known emblem of the evil-eye belief that esfand smoke is also meant to ward off. The bead is glass, not harmal.
A nazar glass bead in Cappadocia, Turkey: the best-known emblem of the evil-eye belief that esfand smoke is also meant to ward off. The bead is glass, not harmal. Photo: Alev Akın · CC BY-SA 4.0 · Wikimedia Commons

Chapter 3Esfand: Syrian rue smoke against the evil eye

No other species in this monograph series will have quite this profile: a plant whose cultural life is larger than its medical one. Across Iran, Afghanistan, Central Asia, Turkey, the Kurdish regions and the Maghreb, esfand seed is burnt on charcoal and the smoke passed over people, doorways, shops, newborns, brides and new cars to avert the evil eye (cheshm-e bad, nazar). Traditional

It is sold on street corners, given at weddings, and accompanied by a spoken formula. This is a living practice, carried on in households today.

The ritual use and the pharmacological use are not the same event.

The pharmacognostic point is that the ritual use and the pharmacological use are not the same event. Burning seed in a brazier and standing in the smoke is a low-dose, largely non-systemic exposure dominated by aroma and the crackle of the capsules; ingesting a seed decoction is a fundamentally different pharmacological act. Sources that treat the incense tradition as evidence of traditional psychoactive dosing are overreading it.

Harmal flower and leaf lobes on sandy ground near Baikonur, Kazakhstan.
Harmal flower and leaf lobes on sandy ground near Baikonur, Kazakhstan. Photo: Yuriy75 · CC BY-SA 3.0 · Wikimedia Commons

Chapter 4In religion and ritual

  • Islamic-world apotropaic use. The dominant tradition: seed capsules burnt as incense against the evil eye and for blessing and purification, from Morocco to Xinjiang. A hadith commonly circulated in this context attributes protective properties to harmal; its authentication is a question for Islamic-studies scholarship, not for me, and I mark it unsourced here rather than repeat it as fact. Traditional
  • Zoroastrian and pre-Islamic Iranian continuity. Harmal smoke is widely described as continuous with pre-Islamic Iranian purificatory fire practice, and the identification of esfand with the Zoroastrian Spenta Armaiti is frequently asserted. The etymological link is plausible and the continuity argument is respectable, but I have not verified it against primary Avestan or Middle Persian scholarship — flagged as unsourced.
  • The haoma/soma candidacy. P. harmala has been proposed as the identity of the Indo-Iranian ritual haoma/soma, most prominently by David Flattery and Martin Schwartz (Haoma and Harmaline, 1989). It is one contested hypothesis among several (ephedra, Amanita muscaria, and others), not a settled identification. Present it as a debate, never as a conclusion. Traditional
  • Grimoire and ritual-magic corpus. Harmal appears in the Arabic magical literature, including the Ghāyat al-Ḥakīm, as a suffumigation ingredient. Its place there is ritual and symbolic, and it should not be read as clinical instruction.
Close-up of the flower, near Madrid, Spain.
Close-up of the flower, near Madrid, Spain. Photo: Adrián Pablo Rodríguez Quiroga · CC0 · Wikimedia Commons

Chapter 5What Syrian rue looks like: botanical description

Dry Peganum harmala capsules on their stalks, split capsules and loose seeds on a white background
Fruiting material — dry three-lobed capsules on their stalks, split capsules showing the seed, and loose seeds (scale bar 1 cm). Muséum de Toulouse collection.
Photo: Roger Culos · CC BY-SA 3.0 · Wikimedia Commons
Peganum harmala flower
Flower — five white to cream petals and prominent yellow stamens, among the narrow, linear leaf lobes.
Photo: Ostenfuchs · CC BY 2.0 · Wikimedia Commons

Habit. Perennial, glabrous, many-stemmed herb or subshrub, typically 30–80 cm tall, forming a dense bushy clump from a deep, woody, creeping taproot system that can reach several metres and makes the plant both drought-proof and, as a weed, nearly ineradicable. Confirmed

Leaves. Alternate, sessile, 4–8 cm, deeply and irregularly dissected into narrow linear lobes — the “wild rue” look that drives the English common name. Bright green, fleshy-textured, strongly and unpleasantly aromatic when crushed.

Flowers. Solitary, terminal, 2.5–3 cm across; 5 (occasionally 4) white to cream petals, narrowly oblong; 12–15 stamens with flattened filaments; sepals linear and often divided, frequently exceeding the petals. Flowering in the arid spring–early summer.

Fruit and seed. A globose, 3-locular (occasionally 4-locular) capsule 6–10 mm diameter, dehiscing at maturity, each capsule carrying roughly 35–60 seeds. Seeds are small (2–4 mm), angular-triangular to obpyramidal, dark brown to blackish, with a characteristically pitted/reticulate testa. The seed is the pharmacologically important organ. Confirmed

Peganum harmala capsules
Capsule, viewed from above — the three-lobed (three-locular) fruit (scale bar 5 mm).
Photo: J.H. Kirkbride Jr, C.R. Gunn & M.J. Dallwitz (2006) · Public domain · Wikimedia Commons
Peganum harmala seeds
Seeds — angular, dark brown, with a pitted testa (scale bar 5 mm). The alkaloid-dense organ, and the object of every authentication question in §6.
Photo: J.H. Kirkbride Jr, C.R. Gunn & M.J. Dallwitz (2006) · Public domain · Wikimedia Commons

Habitat and ecology. Arid and semi-arid steppe, saline flats, overgrazed rangeland, roadsides and disturbed ground; strongly drought- and salt-tolerant; allelopathic, suppressing the germination and growth of neighbouring species — which is both an ecological weapon and a documented research interest in its own right. Unpalatable to stock and toxic to them, so grazing pressure selects for it: overgrazed country fills with harmal.

Peganum harmala in flower, Mazandaran Province, Iran
In flower at Nandal, Mazandaran Province, northern Iran — star-like flowers among buds and finely divided foliage.
Photo: Ninara · CC BY 2.0 · Wikimedia Commons
Peganum harmala shoots in sandy steppe near Baikonur, Kazakhstan
Shoots emerging beside last season’s dead growth, steppe near Baikonur, Kazakhstan.
Photo: Yuriy75 · CC BY-SA 3.0 · Wikimedia Commons

Australian status

Peganum harmala is naturalised in Australia and is treated as an agricultural weed, recorded chiefly in South Australia with records from drier parts of Victoria and New South Wales; it is profiled on Weeds Australia as African rue / Syrian rue, and is toxic to livestock. Declared-weed status differs between states, and biosecurity rules are only one layer. The seed carries harmala alkaloids well above the Schedule 9 exemption levels, and harmaline is a scheduled dangerous drug in Queensland, so do not grow, collect, move or hold the plant without first obtaining legal advice and any authority the law requires. Evidence suggests (weed listing verified; state declaration categories not independently verified).

Dried harmal sold by the bundle at a market in Kentau, Kazakhstan: exactly the kind of traded material that needs authenticating.
Dried harmal sold by the bundle at a market in Kentau, Kazakhstan: exactly the kind of traded material that needs authenticating. Photo: Yuriy75 · CC BY-SA 3.0 · Wikimedia Commons

Chapter 6How to tell real Peganum harmala from a substitute

This section is deliberately conservative. I will not invent micrometre figures for testa cells that I have not measured. What follows is the authentication strategy and the diagnostic characters that are genuinely established.

By eye and by smell (macroscopic and organoleptic)

  • Seeds 2–4 mm, angular/obpyramidal with 3–4 flattened faces, dark brown to blackish, testa distinctly pitted-reticulate. Confirmed
  • Characteristic acrid odour on crushing. Do not taste-test: this is a toxic plant.
  • Capsule fragments in commercial “esfand” are 3-locular and dehisced — a useful gross check that the material is capsule-and-seed, not adulterated seed of another species.

In the laboratory (chemical authentication)

A quick laboratory screen

β-Carbolines fluoresce strongly blue under long-wave UV (365 nm). A methanolic extract of genuine P. harmala seed gives an unmistakable blue fluorescence, and on TLC the harmine and harmaline bands fluoresce brightly. This is fast, cheap, and highly indicative — it will not distinguish P. harmala from another β-carboline-rich source (e.g. Banisteriopsis caapi), but it will immediately separate genuine harmal seed from an inert substitute. Confirmed (standard β-carboline photophysics; the analytical chemistry is exploited directly in the spectrofluorimetric assay of PMID 41108932).

  • HPLC-DAD/MS against reference standards for harmine, harmaline, harmalol, harmol, tetrahydroharmine — this is the definitive identity-plus-potency assay and the only reliable way for a laboratory to establish what a given batch contains. A Chinese quality-standard study exists for the herb (PMID 23270245). Analytical methods for seed infusions specifically have been published (CE-UV, PMID 27377797). Confirmed
  • Chemical fingerprinting by UV-Vis/FTIR/GC-MS/XRD of seeds has been published as a characterisation package (PMID 41038291) — useful as a batch-comparison tool rather than an identity test on its own.
  • Organ-specific alkaloid distribution is itself an authentication tool (see §7 table). If a sample sold as “seed” assays low in harmine/harmaline but high in vasicine, it is aerial material, not seed. That is a real adulteration/substitution signature. Mechanism — the distribution data are confirmed; using them diagnostically is my inference.
Harmal near Tozeur, Tunisia.
Harmal near Tozeur, Tunisia. Photo: MurielBendel · CC BY-SA 4.0 · Wikimedia Commons

Chapter 7What’s in Syrian rue: harmine, harmaline and the rest

Two alkaloid families, in different organs, doing different things. This is the section most often got wrong in secondary sources.

7.1 The β-carbolines: the MAO-active alkaloids

Harmine structure
Harmine · CID 5280953 · C13H12N2O · 212.25 · 7-methoxy-1-methyl-9H-pyrido[3,4-b]indole
Harmaline structure
Harmaline · CID 3564 · C13H14N2O · 214.26 · 7-methoxy-1-methyl-4,9-dihydro-3H-pyrido[3,4-b]indole
Harmalol structure
Harmalol · CID 3565 · C12H12N2O · 200.24 · 1-methyl-4,9-dihydro-3H-pyrido[3,4-b]indol-7-ol
Harmane structure
Harmane · CID 5281404 · C12H10N2 · 182.22 · 1-methyl-9H-pyrido[3,4-b]indole
Tetrahydroharmine structure
Tetrahydroharmine · CID 442118 · C13H16N2O · 216.28 · (1R)-7-methoxy-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole

All structures, depictions and identifiers from PubChem (US National Library of Medicine), retrieved September 2026. The structural logic of the family: a fully aromatic β-carboline (harmine, harmane), its 3,4-dihydro partner (harmaline), the 7-demethylated phenol (harmalol/harmol), and the fully reduced tetrahydro form (THH). Degree of ring saturation and the 7-substituent are what move MAO-A potency and receptor selectivity.

Content and organ distribution — the best single dataset is Herraiz et al. 2010 (PMID 20036304), which quantified the family across organs and tied it directly to MAO inhibition:

Organ Principal β-carbolines (% w/w, dry) MAO-A inhibition (extract IC50)
Seed Harmaline 5.6%; harmine 4.3%; harmalol 0.6%; tetrahydroharmine 0.1% 27 µg/L — potent, reversible, competitive
Root Harmine 2.0%; harmol 1.4% 159 µg/L — strong
Stem / leaf Low Poor inhibitors
Flower Absent —

Source: Herraiz T, González D, Ancín-Azpilicueta C, Arán VJ, Guillén H. Food Chem Toxicol 2010;48(3):839–45. PMID 20036304. Inhibition of MAO-A by seed extract was quantitatively attributable to harmaline and harmine; all extracts were poor MAO-B inhibitors. Confirmed

Why those two numbers matter more than anything else in this article

Roughly 10% of dry seed mass is MAO-A-inhibiting alkaloid, and the harmaline:harmine ratio is about 1.3:1 in favour of harmaline — the more emetic, more tremorgenic, more acutely toxic of the pair. A “small pinch” of seed is not a small dose. Batch-to-batch variation in wild-collected seed means the alkaloid content of any sample is unknown until a laboratory assays it, which is why research and quality-control work on this plant relies on HPLC assay (§6).

7.2 The quinazolines: the respiratory and uterine alkaloids

Vasicine structure
Vasicine (peganine) · CID 667496 · C11H12N2O · 188.23 · (3S)-1,2,3,9-tetrahydropyrrolo[2,1-b]quinazolin-3-ol
Vasicinone structure
Vasicinone · CID 442935 · C11H10N2O2 · 202.21 · (3S)-3-hydroxy-2,3-dihydro-1H-pyrrolo[2,1-b]quinazolin-9-one

Herraiz et al. 2017 (PMID 28279698) isolated and characterised the three major quinazolines — peganine (= vasicine), deoxypeganine (deoxyvasicine) and a newly described peganine β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside. Distribution: peganine high in flowers and leaves; deoxypeganine and peganine high in immature/green fruit; in dry seed, peganine reaches ~1% and the peganine glycoside up to 3.9% w/w; roots and stems low. Confirmed

Critically, the same paper showed that the quinazolines do not contribute to MAO inhibition — that is entirely the β-carbolines. So the psychoactive/MAOI pharmacology and the quinazoline pharmacology are genuinely separable, and the quinazolines are the plausible carriers of the bronchodilator and abortifacient effects reported for the plant. Confirmed (for the MAO finding) / Mechanism (for the attribution of the abortifacient effect).

7.3 Everything else: minor alkaloids, oils and dye

  • Novel and minor alkaloids. The seed is chemically far richer than the textbook four. Wang et al. (J Nat Prod 2017;80(2):551–9, PMID 28128938) reported two racemic pyrroloindole alkaloids (peganines A–B), two rare thiazole derivatives (peganumals A–B), six new β-carbolines (pegaharmines F–K) and 12 known analogues, with moderate HL-60 cytotoxicity (IC50 4.36–9.25 µM) for four of them. Evidence suggests
  • Harmalacidine — an under-studied harmala constituent recently characterised as a potent MAO-A inhibitor in its own right (PMID 41108932). Worth watching; it complicates the assumption that harmine + harmaline account for all MAO activity in a crude extract. Evidence suggests
  • Flavonoids and phenolics. Present, and carry most of the radical-scavenging activity of seed extracts (Herraiz 2017 showed the quinazolines are poor scavengers while whole seed extract is good, which points at the phenolic fraction). Phytochemical content, mineral profile and antioxidant/antidiabetic/anticholinergic profiling with docking has been published (PMID 39960309). I am not going to list specific flavonoid glycosides here: the reports are inconsistent between provenances and I have not verified a definitive set. Partly unsourced.
  • Seed oil. A real and under-appreciated fraction. Essential oil from seeds at different maturation stages has been characterised with antioxidant/antimicrobial testing (PMID 42241271); volatile profiling by multiple preparation methods with an antidepressant-like behavioural readout has also been done (PMID 38971075). The fixed oil has been worked up as a biodiesel feedstock (PMID 38048811) — which tells you the seed carries a substantial non-polar lipid fraction, and is a genuine valorisation angle for a weed biomass. Evidence suggests
  • Dye chemistry — and the “Turkish red” question. Harmal seed yields a red-orange to yellow dye, historically used on wool for carpets across Anatolia, Iran and Central Asia, and the plant’s American common name “Turkish rue” derives from this use. Traditional A modern study demonstrated microwave-assisted extraction and dyeing of chemically and bio-mordanted cotton with harmal seed as the colourant source (PMID 29411282). Confirmed

    The terminological trap: “Turkey red” in textile history means the madder process (Rubia tinctorum, alizarin) — an entirely different dye, plant and chemistry. Harmal dye and Turkey red are not the same thing, and conflating them is a common error. The chromophore of harmal dye is the β-carboline/harmalol fraction rather than an anthraquinone; I have not verified a definitive structural attribution, so the precise chromophore is unsourced.

A wool rug woven by the Qashqai people of Iran. Harmal seed is one of the historical red-to-yellow wool dyes of this region (see the dye note above); the dyes in this particular rug are not documented.
A wool rug woven by the Qashqai people of Iran. Harmal seed is one of the historical red-to-yellow wool dyes of this region (see the dye note above); the dyes in this particular rug are not documented.
Photo: Berndt Fernow · CC BY-SA 3.0 · Wikimedia Commons
A wild harmal clump on a hillside in Iran.
A wild harmal clump on a hillside in Iran. Photo: Amirh. absnd · CC0 · Wikimedia Commons

Chapter 8How it acts and how it harms: pharmacology and toxicity

8.1 How it works: MAO-A inhibition (why harmine is an MAOI)

Harmine and harmaline are potent, reversible, competitive inhibitors of human MAO-A with relative sparing of MAO-B; seed extract IC50 27 µg/L (PMID 20036304). Confirmed

Reversibility is the clinically important word: unlike phenelzine or tranylcypromine, the block lifts as the compound clears, which makes the dietary tyramine risk lower — but lower is not zero, and it does nothing to reduce the serotonergic-drug interaction risk during the exposure window.

The broader β-carboline MAOI pharmacology, including the tobacco and ayahuasca contexts, is reviewed in PMID 35600851.

Drug and food interactions

Contraindicated / high risk: SSRIs, SNRIs, MAOIs, triptans (sumatriptan, rizatriptan and zolmitriptan are MAO-A substrates — this is a listed contraindication for MAOIs), tramadol, pethidine, dextromethorphan, St John’s wort, 5-HTP/tryptophan, linezolid, sympathomimetic decongestants (pseudoephedrine, phenylephrine).
Caution: other serotonergic or sedating botanicals — Hypericum, Rhodiola, Passiflora, Panax ginseng, kava, valerian; tyramine-rich foods (aged cheese, cured meat, soy sauce, tap beer) in any substantial dose.
Overdose signature: nausea and vomiting, tremor, ataxia, bradycardia, agitation, visual disturbance, hallucination. Harmaline is the usual driver.

This is pharmacology, not personal medical advice. Anyone taking a prescription medicine should consult a degree-qualified herbalist with competencies and adequate training in pharmacognosy before using any herbal product. Syrian rue seed is not a herbal product for personal use: see the legal box at the top of this article.

A cluster of harmal seeds (scale bar 5 mm). The seed is the alkaloid-dense part of the plant and the part behind the poisoning reports in this chapter.
A cluster of harmal seeds (scale bar 5 mm). The seed is the alkaloid-dense part of the plant and the part behind the poisoning reports in this chapter.
Photo: Kirkbride, J.H., Jr., C.R. Gunn, and M.J. Dallwitz. 2006. · Public domain · Wikimedia Commons

8.2 The diabetes research: DYRK1A inhibition

Separate from MAO entirely: harmine is a potent inhibitor of the kinase DYRK1A, and DYRK1A inhibition is currently the leading pharmacological route to human β-cell proliferation. The chain of evidence is strong and comes from a serious group:

  • Combined DYRK1A + SMAD (TGF-β) + trithorax pathway inhibition drives robust replication in adult human β cells (PMID 30581122). Evidence suggests
  • Genetic and pharmacological dissection confirming DYRK1A as the mitogenic target (PMID 31821176).
  • A CNS-avoidant, selective harmine-derived DYRK1A inhibitor was designed and validated specifically to keep the β-cell effect and lose the β-carboline CNS pharmacology (PMID 32003560) — i.e. the field is actively engineering the psychoactivity out.
  • Harmine + exendin-4 expanded human β-cell mass in vivo in a mouse xenograft, a combination the authors describe as safe in that model (PMID 38985854, Sci Transl Med 2024). Evidence suggests
  • Mechanistic follow-up: harmine drives human β-cell differentiation and function via PKA pathways (PMID 41573826, preprint — flagged as bioRxiv, not peer-reviewed); α-cell origin of regenerated β cells (PMID 39626675).
What this does, and does not, mean

This is the one area where “Peganum harmala for diabetes” has a real mechanistic spine.

Note carefully what it does not license: none of this is evidence that eating harmal seed regenerates β cells in a person. The work is on isolated harmine and engineered analogues, at controlled exposures, largely in xenograft models.

8.3 Other targets in the body

  • Benzodiazepine/GABAA site. β-Carbolines have a genuine, historically important relationship with the benzodiazepine site — norharman binding sites were characterised in rat brain (PMIDs 3366173, 2156525, 8232719), carboline interactions with GABA and BZD receptors were studied directly (PMID 3031382), and flumazenil-sensitive behaviour has been demonstrated with harmine (PMID 2846933). Evidence suggests — this literature is old, largely rodent, and the affinities are modest; it justifies saying “these are not purely MAO drugs”, not a claim of anxiolytic action.
  • Harmaline and the inferior olive. Harmaline is the standard pharmacological model of essential tremor, acting through olivocerebellar rhythmicity — used as a model, not proposed as a therapy (PMIDs 39368533, 34925722, 33048308). Confirmed as a model system. This is also the mechanistic basis of tremor as an overdose sign.
  • Efflux transporters. Harmane, harmine and norharman inhibit MDR1 and MRP1 in cancer cells (PMID 41276548) — relevant both as an anticancer angle and as an under-recognised interaction mechanism. Mechanism

8.4 How the body handles it: pharmacokinetics

Human PK is known mainly from the DMT/harmine co-administration work (§11): oral harmine is subject to heavy first-pass metabolism (primarily CYP-mediated O-demethylation to harmol, then conjugation), which is why the route of administration dominates the exposure.

Population PK-PD modelling of co-administered DMT and harmine in healthy subjects (PMID 40639043) and a PBPK model spanning rats and humans (PMID 40839168) are the current best descriptions; a PBPK model predicting ayahuasca-alkaloid/SSRI interactions has also been published (PMID 41788629). Confirmed (human PK data exist and are controlled) — with the caveat that all of it describes isolated harmine or a defined formulation, not a seed decoction.

8.5 Side effects, poisoning and overdose in people

Documented human harm

  • Fatal poisoning of pregnant women by P. harmala — case report series, PMID 34401132 (Ann Med Surg 2021). Confirmed
  • P. harmala intoxication in a pregnant woman — PMID 24955262 (Case Rep Emerg Med 2014). Confirmed
  • The traditional abortifacient/emmenagogue use (§2) and the quinazoline uterotonic pharmacology (§7.2) are the direct route to this harm. Pregnancy is an absolute contraindication.
  • Herraiz’s 2017 paper explicitly notes the plant is “increasingly involved in toxic cases” as recreational ayahuasca-analogue use spreads. Confirmed
  • In mice, central inhibition prevents the acute toxicity of harmine (PMID 34078836) — i.e. the acute lethality is CNS-mediated. Mechanism

On hepatic effects the literature is genuinely two-directional, which is worth stating plainly rather than cherry-picking: rodent studies report hepatoprotective activity against ethanol-induced damage (PMID 25974007) and seed oil protecting against plasticiser-induced hepatic/cardiac/brain injury (PMID 33396140), while high-dose alkaloid exposure is hepatotoxic and neurotoxic. Dose decides. Evidence suggests

Flower and buds of harmal, Akmachit.
Flower and buds of harmal, Akmachit. Photo: Mirishkorlik · CC BY-SA 4.0 · Wikimedia Commons

Chapter 9Is Syrian rue used in medicine today?

The headline finding of this monograph

As of September 2026 I can find no controlled clinical trial of Peganum harmala, or of any whole-plant preparation of it, for any therapeutic indication. The human trial literature on its constituents consists of pharmacokinetic and pharmacodynamic studies of isolated harmine co-administered with DMT in healthy volunteers (§11) — safety and exposure work in a psychedelic-development context, not therapeutic trials of the herb. Every therapeutic claim below is therefore preclinical, traditional, or both. Anyone who tells you otherwise — including us — is wrong.

9.1 Traditional uses

Evidence of practice, not of efficacy.

Traditional throughout. Across Persian, Unani, Arabic-Islamic, Uyghur/Chinese and North African systems, harmal is classed as a “hot, dry” drug used for: joint pain and rheumatic complaints; colic and digestive spasm; intestinal worms; amenorrhoea and menstrual obstruction (and, explicitly, as an abortifacient — see §8.5); cough and asthma (aerial parts, in Chinese practice — this is the quinazoline indication and the one with the best mechanistic support); low mood; lice and skin parasites; and as fumigation for purification and against the evil eye.

The standard modern review of traditional use is Moloudizargari et al. (Pharmacogn Rev 2013;7(14):199–212, PMID 24347928). A more recent botany/traditional-use/phytochemistry/pharmacology/quality-marker/toxicity review is Li (PMID 37350001).

Fruiting harmal, its capsules turning orange, at the Jeyran breeding centre, Bukhara region, Uzbekistan.
Fruiting harmal, its capsules turning orange, at the Jeyran breeding centre, Bukhara region, Uzbekistan.
Photo: Humoyun Mehridinov · CC BY-SA 4.0 · Wikimedia Commons

9.2 Where the laboratory and animal evidence is strongest

Area What actually exists Grade
Respiratory (antitussive, expectorant, bronchodilator) The best-characterised non-CNS activity. Vasicine, deoxyvasicine and vasicinone from aerial parts, dosed orally at 5/15/45 mg/kg in mice and guinea pigs: significant cough suppression (comparable to codeine phosphate 30 mg/kg at the top dose), increased phenol-red secretion, and prolonged pre-convulsive time against acetylcholine/histamine bronchoconstriction (aminophylline comparator). PMID 26547531. Consistent with the long use of vasicine-bearing Adhatoda vasica and with bromhexine/ambroxol being vasicine-derived. Evidence suggests (animal)
Antiparasitic / antileishmanial A coherent, multi-decade line: harmine in vesicular delivery systems (PMID 15203896); peganine HCl dihydrate as an orally active antileishmanial with structure-based target work (PMIDs 19339182, 18694906); P. harmala vs L. major in vitro/ex vivo (PMID 34598403); anti-amoebic activity against Acanthamoeba (PMID 34357992). Broad antimicrobial review: PMID 35807407. Evidence suggests
Metabolic / antidiabetic Rodent: seed extract in streptozotocin-diabetic rats (PMID 40365181); hippocampal apoptosis modulation in diabetic rats (PMID 36915407); harmine reducing diabetic testicular damage (PMID 38757277); α-amylase/α-glucosidase inhibition in vitro (PMIDs 39135016, 32164186). Plus the entire DYRK1A β-cell programme (§8.2) — mechanistically the most important, and the least about the herb. Evidence suggests (animal/in vitro)
Anti-inflammatory / antiarthritic P. harmala appraised for anti-arthritic and anti-inflammatory potential (PMID 33563161); harmaline in a rheumatoid-arthritis context with a novel HOCl-probe angle (PMID 39096720); harmine modulating macrophage polarisation and osteogenic differentiation in inflammatory bone destruction (PMID 34079546); harmine enhancing type-H vessel formation and preventing bone loss in ovariectomised mice (PMID 29721090). Evidence suggests (animal)
Oncology Large and growing in vitro/in vivo literature: harmine derivatives with selective antileukaemic activity (PMID 41668452); harmine in ovarian cancer EMT via HDAC7/RECK (PMID 41061932); network-pharmacology plus validation in gastric cancer (PMID 41942580); harmane inducing apoptosis via RRM2B in colorectal cancer (PMID 42262096); MDR1/MRP1 inhibition to address chemoresistance (PMID 41276548). Structure–activity review: PMID 40024888. Evidence suggests (preclinical only — no human oncology trial)
Neuro / psychiatric Neuroprotective mechanisms of harmine reviewed (PMID 38758470); harmaline and the gut–brain–immune axis in neuroinflammation/ulcerative colitis (PMID 42417936); antidepressant-like activity of the volatile fraction in animals (PMID 38971075); β-carboline MAOI psychopharmacology reviewed (PMID 35600851). Evidence suggests

9.3 What the evidence does and does not support

  • Supported: P. harmala is a major traditional medicine of the Persianate and Islamic world; its seeds are an exceptionally rich source of reversible MAO-A-inhibiting β-carbolines; and its constituents are under active, serious pharmaceutical investigation — most notably harmine in β-cell regeneration.
  • Not supported: any claim that it treats diabetes, cancer, arthritis, depression, leishmaniasis or migraine in humans. There is no clinical evidence for any of those, and in Australia the Schedule 9 position makes therapeutic promotion a regulatory matter as well as a scientific one.
  • Migraine, specifically. The serotonin-depletion model of migraine makes a fast-acting reversible MAO-A inhibitor mechanistically interesting. But there is no trial of harmala in migraine, the plant’s emetic and other acute effects would confound any informal observation, and the traditional-use claim is itself unsourced (§2). Mechanism — a hypothesis, not a finding.
Harmal in cultivation at the botanical garden in Poznań, Poland.
Harmal in cultivation at the botanical garden in Poznań, Poland. Photo: Krzysztof Ziarnek, Kenraiz · CC BY-SA 4.0 · Wikimedia Commons

Chapter 10Where the research is heading

  1. DYRK1A inhibitors for β-cell regeneration — the one genuinely translational programme. The field has already produced CNS-avoidant harmine analogues (PMID 32003560) and combination regimens expanding human β-cell mass in vivo (PMID 38985854); a 2026 medicinal-chemistry review surveys the scaffold landscape (PMID 42634309). Watch for first-in-human dosing. This is the most likely route by which a Peganum-derived molecule becomes a registered medicine.
  2. Harmine as a psychedelic-adjunct pharmacological tool — the DMT/harmine formulation work (§11) is being pursued explicitly to make DMT clinically tractable; harmine there serves as enabling pharmacology for DMT, which is the agent under study.
  3. Quinazoline respiratory agents — vasicine chemistry already gave medicine bromhexine and ambroxol; P. harmala aerial parts are an alternative, weed-abundant source.
  4. Chemoresistance reversal — β-carboline inhibition of MDR1/MRP1 (PMID 41276548) is an under-explored adjunct hypothesis.
  5. Weed-biomass valorisation — a naturalised weed that is simultaneously a dye source, a seed-oil/biodiesel feedstock (PMID 38048811) and an alkaloid source is an unusual circular-economy proposition.
  6. Allelopathy / bioherbicide — the alkaloids have differential effects on dicot and monocot crops, which is a real agronomic research line.
Harmal flowering in the Hrazdan valley, Yerevan, Armenia.
Harmal flowering in the Hrazdan valley, Yerevan, Armenia.
Photo: Krzysztof Ziarnek, Kenraiz · CC BY-SA 4.0 · Wikimedia Commons
Flowers of Banisteriopsis caapi, the ayahuasca vine and the other major β-carboline source discussed in this chapter.
Flowers of Banisteriopsis caapi, the ayahuasca vine and the other major β-carboline source discussed in this chapter. Photo: Maria Gabriela Yejo · CC0 · Wikimedia Commons

Chapter 11Ayahuasca analogues and “underground” use

The mechanism, stated plainly. Orally ingested DMT is inactive because gut and hepatic MAO-A destroy it before it reaches the systemic circulation. A reversible MAO-A inhibitor present at the same time blocks that first-pass degradation, which is the pharmacological basis of ayahuasca.

In traditional Amazonian ayahuasca the MAOI comes from Banisteriopsis caapi; in the globalised “anahuasca” or “pharmahuasca” practice, P. harmala seed is the commonest substitute because it is widely traded and far more alkaloid-dense. It is not a lawful substitute in Australia: see the legal box at the top of this article. Confirmed

Comparative chemistry of traditional versus analogue ayahuasca has been published (PMID 32896230), as have analytical methods for harmala seed infusions specifically (PMID 27377797) and salivary/serum kinetics of DMT and β-carbolines after oral ayahuasca in a religious context (PMID 33119972).

The controlled clinical work. This is where the only real human trial data on harmine sit:

  • First-in-human trial of novel administration routes for DMT and harmine, aimed at overcoming the clinical limitations of traditional ayahuasca (PMID 38089057).
  • Randomised controlled PK/PD of an innovative DMT/harmine formulation in healthy participants (PMID 39774840).
  • Factorial dose-escalation examining the DMT–harmine interaction in healthy volunteers (PMID 39923404), with population PK-PD modelling (PMID 40639043).

Confirmed — these are genuine human studies, in healthy volunteers, on defined isolated compounds under clinical supervision. They are not evidence that self-prepared seed decoctions are safe.

Safety facts for anyone who encounters this practice

  • Dose uncertainty is the core hazard. Wild seed at ~10% β-carboline w/w varies widely from batch to batch, so no home preparation of the seed has a predictable or safe dose.
  • Harmaline dominates the seed and is the more emetic, tremorgenic and toxic of the pair — the adverse-effect profile of harmal-based analogues is worse than that of B. caapi-based traditional brews at comparable MAOI effect.
  • The MAOI window is the drug-interaction window. Serotonin toxicity with SSRIs/SNRIs/triptans/tramadol is the realistic fatal-adverse-event pathway, and PBPK modelling of exactly this interaction now exists (PMID 41788629).
  • Australian law: harmala alkaloids and DMT are both Schedule 9. Nothing in this section is advice to obtain or use either.
  • If someone is unwell: call 000 in an emergency, or the Poisons Information Centre on 13 11 26.
A flowering harmal bush in sand near Baikonur, Kazakhstan.
A flowering harmal bush in sand near Baikonur, Kazakhstan. Photo: Yuriy75 · CC BY-SA 3.0 · Wikimedia Commons

Chapter 12Related plants and medicines

Property or use Related plant or medicine Note
Reversible MAO-A inhibition, clinically Moclobemide A prescription-only medicine in Australia: dose-defined and not a β-carboline. Whether it suits anyone is a decision for their prescriber.
β-Carboline MAOI in a traditional context Banisteriopsis caapi Harmine/harmaline/THH, but a markedly higher THH fraction and a gentler adverse profile; also Schedule 9 in Australia by virtue of its alkaloids.
Vasicine/quinazoline respiratory action Adhatoda vasica (malabar nut); bromhexine/ambroxol The same chemistry with a far better safety record and, for the semi-synthetics, registered products.
Trace β-carboline / mild sedative-anxiolytic Passiflora incarnata Contains harman-type alkaloids at trace level; not an MAOI at herbal doses. Do not combine with harmal.
Anthelmintic, emmenagogue, antiparasitic traditional roles Species-appropriate registered agents The traditional indications are precisely where harmal’s toxicity did its historical damage.
Red-orange natural dye Rubia tinctorum (madder) The actual “Turkey red” chemistry — see §7.3.
Trunk of a mature Banisteriopsis caapi vine, Centro Takiwasi botanical garden, Peru.
Trunk of a mature Banisteriopsis caapi vine, Centro Takiwasi botanical garden, Peru.
Photo: Jaime Torres/Archivo Centro Takiwasi · CC BY-SA 4.0 · Wikimedia Commons
Peganum harmala in flower, Georgia.
Peganum harmala in flower, Georgia. Photo: Lazaregagnidze · CC BY-SA 3.0 · Wikimedia Commons

Discussion: conclusions, hypotheses and research still required

What the evidence supports

Confirmed Syrian rue is chemically unusual because its seeds are rich in β-carboline alkaloids, chiefly harmine and harmaline, with reversible MAO-A inhibition as the central pharmacological fact. Traditional The cultural record also supports a separate conclusion: Peganum harmala is a major plant in Persianate, Islamic, North African and Central Asian ritual and household practice, especially as protective smoke. Evidence suggests The biomedical literature is strongest for isolated constituents and preclinical models; it does not establish the whole plant as a human treatment for diabetes, cancer, arthritis, depression, migraine or infection.

Hypotheses and musings worth keeping alive

Mechanism The cleanest translational hypothesis is harmine-like DYRK1A inhibition as a medicinal-chemistry scaffold for β-cell regeneration. It does not extend to the whole plant as a medicine. Mechanism The quinazoline fraction also deserves more attention as a respiratory-pharmacology lead, because vasicine chemistry has a better safety precedent than the seed β-carbolines. Mechanism Harmal’s cultural use as smoke may preserve observations about scent, ritual state and household protection, but that is a different exposure route from ingestion and should be studied as fumigation chemistry and ethnobotany. It gives no basis for therapeutic advice.

Where research should begin

  • Botany / QA: secure authenticated voucher material and build a local microscopy and HPLC reference set for seed, aerial parts and likely substitutes.
  • Phytochemistry: map batch-to-batch alkaloid variation across geography, plant part, season and storage, including harmine:harmaline ratios and quinazoline markers.
  • Pharmacology: separate β-carboline, quinazoline and whole-extract effects instead of treating “harmal” as one pharmacological object.
  • Toxicology / medicine: collate Australian poison-centre and hospital presentations, especially interactions with serotonergic medicines, and only then consider any ethics-approved clinical question.
  • Ethnobotany / history: trace Persian, Arabic, Uyghur and North African primary sources for smoke, headache, melancholia, childbirth and protection claims, separating attested practice from later internet repetition.
  • Regulatory science: keep the Schedule 9 position and any research-permit pathway current before any specimen handling, teaching display or analytical work is planned.

About AIP and this series

The Australian Institute of Pharmacognosy (AIP) is based in Cardwell, in the wet tropics of far north Queensland. Pharmacognosy is the study of medicines and poisons that come from natural sources: how a plant is identified, what it contains, and what that chemistry does in the body.

This monograph series is part of our education and research work. Each monograph follows the same structure and grades every claim by the evidence behind it, so you can see what is tradition, what is laboratory or animal work, and what has actually been tested in people.

Nothing in this series is an offer of treatment, a product or a service, and nothing in it is a reason to use a plant. If you find an error, or a source we have missed, we would like to hear about it.

References

Show all 69 references (every PMID links to PubMed)

All PMIDs verified against PubMed on 12 September 2026; chemical identifiers verified against PubChem the same day. Listed in order of first citation.

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About this monograph

AIP monographs are written to a fixed thirteen-section standard and grade every substantive claim by the kind of evidence behind it. We would rather tell you a claim is unsourced than repeat it. If you find an error, or a source we have missed, we want to hear about it.

Suggested citation: Ridley T. Syrian rue (Peganum harmala L.): an evidence-graded monograph. AIP Monograph No. 2. Cardwell (QLD): Australian Institute of Pharmacognosy; 2026.

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