Calamus

Calamus is vacha in Ayurveda, and the rhizome is the part used. It is classed as pungent and bitter in taste and heating in effect, a warming, drying, stimulating drug ^{1,2Reference 1Rajput SB et al et al. · 2014ReviewAn overview on traditional uses and pharmacological profile of Acorus calamus Linn. (Sweet flag) and other Acorus species — reviewView study →Reference 2Khwairakpam AD et al et al. · 2018ReviewAcorus calamus: a bio-reserve of medicinal values — reviewView study →}.

On the digestive side it is a carminative and a bitter for sluggish digestion, gas and colic. On the mental side it belongs to the medhya group, the herbs given for speech, memory and clarity of mind, and it has a long traditional use in epilepsy ^{1,6Reference 1Rajput SB et al et al. · 2014ReviewAn overview on traditional uses and pharmacological profile of Acorus calamus Linn. (Sweet flag) and other Acorus species — reviewView study →Reference 6Bhat SD et al et al. · 2012AnimalAnticonvulsant activity of raw and classically processed Vacha (Acorus calamus Linn.) rhizomes — animal in vivoView study →}.

The raw rhizome is not dispensed. It is first put through shodhana, a classical purification ^{6Reference 6Bhat SD et al et al. · 2012AnimalAnticonvulsant activity of raw and classically processed Vacha (Acorus calamus Linn.) rhizomes — animal in vivoView study →}.

Western herbalism uses calamus as a warming aromatic bitter: a digestive stimulant and carminative, and an expectorant for damp coughs.

Native American peoples used sweet flag as a medicine and in ceremony. The tribes recorded as using it lived within the range of the native North American sweet flag, Acorus americanus ^{55Reference 55Thompson · 2000Acorus calamus Linnaeus — species description, habitat and distribution — floraView study →}.

In isolated rabbit jejunum, a crude ethanol extract inhibited spontaneous and high-K⁺-induced contractions (EC₅₀ 0.42 and 0.13 mg/mL), consistent with calcium-channel blockade rather than a receptor-specific action ^{14Reference 14Gilani AU et al et al. · 2006In vitroAntispasmodic effect of Acorus calamus Linn. is mediated through calcium channel blockade — in vitroView study →}.

The same mechanism relaxed pre-contracted guinea-pig trachea, adding a bronchodilator effect from combined Ca²⁺-channel blockade and muscarinic antagonism ^{15Reference 15Shah AJ et al et al. · 2010AnimalBronchodilatory effect of Acorus calamus (Linn.) is mediated through multiple pathways — animal in vivoView study →}.

A β-asarone-free oil kept its spasmolytic activity against histamine-induced ileal spasm, matching the antihistamine pyrilamine, while a β-asarone-rich oil showed no spasmolytic activity at the same concentration ^{16Reference 16Keller K et al et al. · 1985In vitroSpasmolytische wirkung des isoasaronfreien kalmus1 — in vitroView study →}.

Gap: every result is an isolated-organ preparation. No human study has tested calamus for dyspepsia, colic or bronchospasm, and no oral dose has been defined for any of them.

Raw and classically processed rhizome both shortened the tonic-extensor phase in maximal electroshock, with the processed form also reducing convulsion and stupor ^{6Reference 6Bhat SD et al et al. · 2012AnimalAnticonvulsant activity of raw and classically processed Vacha (Acorus calamus Linn.) rhizomes — animal in vivoView study →}.

In a ferric-chloride epileptogenesis model, 200 mg/kg orally for 14 days reduced seizure behaviour and spike-wave discharges while lowering brain lipid peroxidation ^{7Reference 7Hazra R et al et al. · 2007AnimalInhibitory role of Acorus calamus in ferric chloride-induced epileptogenesis in rat — animal in vivoView study →}.

A sub-anticonvulsant dose of hydroalcoholic extract potentiated both sodium valproate and carbamazepine in the pentylenetetrazole model, protecting better than either drug alone ^{8Reference 8Katyal J et al et al. · 2012AnimalInteraction of hydroalcoholic extract of Acorus calamus Linn. with sodium valproate and carbamazepine — animal in vivoView study →}. No human study has tested the combination.

The studies are animal-only, and most use whole rhizome of unspecified chemotype.

A hydroalcoholic extract (600 mg/kg) restored Morris water-maze performance and normalised acetylcholinesterase, SOD and glutathione in scopolamine-induced dementia ^{9Reference 9Malik R et al et al. · 2024AnimalAntioxidative and neuroprotective potential of Acorus calamus linn. and Cordia dichotoma GView study →}, and isolated α-asarone (15–30 mg/kg for 14 days) reversed scopolamine amnesia while lowering cortical and hippocampal AChE ^{10Reference 10Venkatesan K · 2022AnimalAnti-amnesic and anti-cholinesterase activities of α-asarone against scopolamine-induced memory impairments in rats — animal in vivoView study →}.

Both protected spatial memory under noise stress ^{11Reference 11Sundaramahalingam M et al et al. · 2013AnimalRole of Acorus calamus and alpha-asarone on hippocampal dependent memory in noise stress exposed rats — animal in vivoView study →} and preserved Na⁺/K⁺-ATPase under restraint stress ^{12Reference 12Reddy S et al et al. · 2015AnimalEffects of Acorus calamus Rhizome Extract on the Neuromodulatory System in Restraint Stress Male Rats — animal in vivoView study →}.

Mechanistically, β-asarone promoted autophagy and reduced amyloid-β accumulation in an Alzheimer’s cell model ^{13Reference 13Wang N et al et al. · 2019In vitroWang N et al. (2019). β-Asarone Inhibits Amyloid-β by Promoting Autophagy in a Cell Model of Alzheimer’s Disease — in vitro. Front Pharmacol. https://pubmed.ncbi.nlm.nih.gov/32009952/View study →}, and an older study found broad CNS-depressant activity in the ethanol extract ^{53Reference 53Vohora SB et al et al. · 1990AnimalCentral nervous system studies on an ethanol extract of Acorus calamus rhizomes — animal in vivoView study →}.

No human cognition trial exists, and the mechanistic work centres on α- and β-asarone rather than the whole rhizome.

A methanol extract (500 mg/kg) dose-dependently reduced paw swelling, arthritis scores and TNF-α/CRP in adjuvant-induced arthritic rats via the OPG/RANKL pathway ^{23Reference 23Bari MU et al et al. · 2026AnimalAnti-arthritic appraisal of Acorus calamus L. extracts in complete Freund’s adjuvant‑induced arthritic Wistar rats via regulating inflammatory cytokines and OPG/RANKL pathway — animal in vivoView study →}.

In ovalbumin-induced allergic asthma, an ethanol extract (50–200 mg/kg) lowered IL-4, total IgE and nitric oxide while raising IFN-γ ^{24Reference 24Zaheri Abdevand Z et al et al. · 2025AnimalThe evaluation of the anti-inflammatory effects of Acorus calamus L. ethanolic extract on ovalbumin-induced allergic asthma in mice — animal in vivoView study →}, and α-asarone stabilised mast cells and suppressed IL-5/IL-13 through ERK/JAK2-STAT3 inhibition ^{25Reference 25Bai H et al et al. · 2023AnimalBai H et al. (2023). α-Asarone alleviates allergic asthma by stabilizing mast cells through inhibition of ERK/JAK2-STAT3 pathway — animal in vivo. Biofactors. https://pubmed.ncbi.nlm.nih.gov/35861676/View study →}.

A leaf water extract attenuated NF-κB and IRF3 activation and IL-6/IL-8 expression in keratinocytes ^{26Reference 26Kim H et al et al. · 2009In vitroAnti-inflammatory activity of a water extract of Acorus calamus L. leaves on keratinocyte HaCaT cells — in vitroView study →}, with NF-κB downregulation the common thread. Every model is animal or cell-based, and the extracts differ enough between studies that no single preparation is validated.

An ethanol extract (25 mg/kg) improved motor function and cut infarct area from 33% to 19% after middle-cerebral-artery occlusion in rats, raising SOD and glutathione ^{17Reference 17Shukla PK et al et al. · 2006AnimalNeuroprotective effect of Acorus calamus against middle cerebral artery occlusion-induced ischaemia in rat — animal in vivoView study →}.

In traumatic brain injury, a Drosophila paradigm ^{18Reference 18Kalra S et al et al. · 2024AnimalAcorus calamus Linn.: A novel neuroprotective approach for traumatic brain injury in Drosophila melanogaster — animal in vivoView study →} and a mouse weight-drop model using α-asarone (12.5–50 mg/kg) and extract (190 mg/kg) both reduced blood-brain-barrier permeability, oxidative stress and mortality ^{19Reference 19Kalra S et al et al. · 2025AnimalNeuroprotection in traumatic brain injury: effects of alpha-asarone and Acorus calamus extract in mice using weight drop model — animal in vivoView study →}.

In vitro, extract and α-asarone protected hippocampal neurons from glutamate and ER-stress death by lowering ROS and PERK phosphorylation ^{20Reference 20Mikami M et al et al. · 2021In vitroAcorus calamus extract and its component α-asarone attenuate murine hippocampal neuronal cell death induced by l-glutamate and tunicamycin — in vitroView study →}.

Much of this work used isolated α-asarone rather than a whole-rhizome preparation.

Ethyl-acetate and methanolic extracts protected six regions of rat brain against noise-stress oxidative damage, restoring SOD, catalase and glutathione ^{21Reference 21Manikandan S et al et al. · 2005AnimalProtective effect of Acorus calamus LINN on free radical scavengers and lipid peroxidation in discrete regions of brain against noise stress exposed rat — animal in vivoView study →}.

At 100–200 mg/kg orally for seven days, the extract reduced nickel-chloride-induced renal oxidative stress, lipid peroxidation and hyperproliferation ^{22Reference 22Prasad L et al et al. · 2006AnimalAcorus calamus extracts and nickel chloride: prevention of oxidative damage and hyperproliferation response in rat kidney — animal in vivoView study →}.

The activity is attributed to the rhizome’s phenolic acids, caffeic acid and chlorogenic acid, alongside the asarones. The endpoints are biomarkers in stressed rodents, with no clinical endpoint.

The antidiabetic activity sits in the rhizome’s ethyl-acetate fraction. In streptozotocin and db/db mice, the fraction (100 mg/kg) lowered fasting glucose and raised plasma GLP-1 and insulin, upregulating incretin genes in intestinal L-cells ^{27Reference 27Liu YX et al et al. · 2015In vitroEffects and molecular mechanisms of the antidiabetic fraction of Acorus calamus L. on GLP-1 expression and secretion in vivo and in vitro — animal in vivoView study →}.

Related work found insulin sensitisation — lower glucose, triglycerides and free fatty acids, higher adiponectin in db/db mice, better glucose uptake in L6 myotubes ^{28Reference 28Wu HS et al et al. · 2009In vitroInsulin sensitizing activity of ethyl acetate fraction of Acorus calamus L. in vitro and in vivo — animal in vivoView study →} — plus α-glucosidase inhibition and increased insulin release from HIT-T15 cells at 400–800 mg/kg ^{29Reference 29Si MM et al et al. · 2010In vitroInsulin releasing and alpha-glucosidase inhibitory activity of ethyl acetate fraction of Acorus calamus in vitro and in vivo — animal in vivoView study →}.

Gap: the active material is an ethyl-acetate fraction, which is a laboratory preparation rather than a rhizome powder or a tincture. Nothing shows the traditional forms carry the same activity.

A hydroalcoholic extract (100–200 mg/kg for 14 days) attenuated thermal and mechanical hyperalgesia and allodynia in chronic-constriction-injury ^{30Reference 30Muthuraman A et al et al. · 2011AnimalAttenuating effect of Acorus calamus extract in chronic constriction injury induced neuropathic pain in rats: an evidence of anti-oxidative, anti-inflammatory, neuroprotective and calcium inhibitory effects — animal in vivoView study →}, vincristine-induced ^{31Reference 31Muthuraman A et al et al. · 2011AnimalAttenuating effect of hydroalcoholic extract of Acorus calamus in vincristine-induced painful neuropathy in rats — animal in vivoView study →} and nerve-transection ^{32Reference 32Muthuraman A et al et al. · 2011AnimalEffect of hydroalcoholic extract of Acorus calamus on tibial and sural nerve transection-induced painful neuropathy in rats — animal in vivoView study →} neuropathy, each time lowering superoxide, myeloperoxidase and calcium alongside the behavioural benefit.

All three studies come from one group using one extract, so nothing here has been independently replicated, and the mechanism offered is anti-oxidative rather than a distinct analgesic pathway.

Crude extract lowered mean arterial pressure in normotensive rats through Ca²⁺ antagonism and a nitric-oxide component ^{33Reference 33Shah AJ et al et al. · 2009AnimalBlood pressure-lowering and vascular modulator effects of Acorus calamus extract are mediated through multiple pathways — animal in vivoView study →}.

An aqueous-methanolic extract produced cardiac depression with EDHF-mediated coronary vasodilation ^{34Reference 34Shah AJ et al et al. · 2012AnimalAqueous-methanolic extract of sweet flag (Acorus calamus) possesses cardiac depressant and endothelial-derived hyperpolarizing factor-mediated coronary vasodilator effects — animal in vivoView study →}.

A 30-day course attenuated isoproterenol-induced cardiomyopathy via reduced calcineurin and oxidative stress ^{35Reference 35Singh BK et al et al. · 2011AnimalIsoproterenol-induced cardiomyopathy in rats: influence of Acorus calamus Linn.: A. calamus attenuates cardiomyopathy — animal in vivoView study →}.

A 2026 study traced the vasorelaxation to β-asarone itself (1–30 µg/mL, L-type VDCC modulation) ^{36Reference 36Parashar S et al et al. · 2026AnimalParashar S et al. (2026). β-Asarone-induced vasorelaxation in isolated rat mesenteric artery: An efficacy vs toxicity paradox of Acorus calamus — animal in vivo. J Ethnopharmacol. https://pubmed.ncbi.nlm.nih.gov/41519184/View study →}.

Gap: the vasoactive constituent is β-asarone, the constituent kept low in the safer types of the plant.

Activity is broad in vitro, almost all of it from the essential oil or β-asarone. β-Asarone inhibited Candida albicans growth and biofilm and was fungicidal at higher concentrations ^{37Reference 37Rajput SB et al et al. · 2013In vitroRajput SB et al. (2013). β-Asarone, an active principle of Acorus calamus rhizome, inhibits morphogenesis, biofilm formation and ergosterol biosynthesis in Candida albicans — in vitro. Phytomedicine. https://pubmed.ncbi.nlm.nih.gov/23123225/View study →}.

The essential oil showed bactericidal MBCs of 0.032–0.143 mg/mL against Gram-positive and -negative bacteria and fungi ^{38Reference 38Joshi RK · 2016In vitroAcorus calamus Linn.: phytoconstituents and bactericidal property — in vitroView study →}, and inhibited Aspergillus flavus and A. niger, with (Z)-asarone dominant ^{39Reference 39Bisht D et al et al. · 2011In vitroTerpenoid composition and antifungal activity of three commercially important essential oils against Aspergillus flavus and Aspergillus niger — in vitroView study →}.

An ethanolic extract was broadly antibacterial, including against MRSA and ESβL producers ^{40Reference 40Aqil F et al et al. · 2007In vitroAntibacterial properties of traditionally used Indian medicinal plants — in vitroView study →}.

Gap: the active fraction is the volatile oil, which is also the form behind the recorded poisonings ^{52Reference 52Björnstad K et al et al. · 2009Case reportBioanalytical investigation of asarone in connection with Acorus calamus oil intoxications — human case seriesView study →}. The water and alcohol preparations the herb is taken as were not the ones tested.

This rests on isolated polysaccharide fractions, not the whole herb or its asarones. A water-soluble polysaccharide activated macrophages, stimulated IL-12 and nitric oxide, and promoted a Th1 response while suppressing Th2-dependent IgG1/IgE in mice ^{41Reference 41Belska NV et al et al. · 2010AnimalWater-soluble polysaccharide obtained from Acorus calamus L. classically activates macrophages and stimulates Th1 response — animal in vivoView study →}.

A related screen found calamus polysaccharides stimulated macrophage NO synthase at levels comparable to LPS ^{42Reference 42Danilets MG et al et al. · 2010In vitroEffect of plant polysaccharides on TH1-dependent immune response: screening investigation — in vitroView study →}.

Separately, a benzene rhizome extract protected against stress-induced immunosuppression, preserving leukocyte and lymphocyte counts and bone-marrow cellularity ^{43Reference 43Sarjan HN et al et al. · 2017AnimalThe protective effect of the Vacha rhizome extract on chronic stress-induced immunodeficiency in rat — animal in vivoView study →}.

All of it is constituent-level, tied to specific isolates, with no whole-herb or human data.

Water-soluble polysaccharides enhanced chemotherapy efficacy while reducing cytostatic toxicity to blood, liver and intestinal epithelium in tumour-bearing animals ^{44Reference 44Safonova EA et al et al. · 2012AnimalProspects for the use of plant polysaccharides in complex treatment of malignant tumors — animal in vivoView study →}.

A defined polysaccharide reduced Lewis-lung-carcinoma tumour size and metastasis with lower CD274/CD326 expression ^{45Reference 45Lopatina KA et al et al. · 2017AnimalEffect of Acorus calamus LView study →}.

An extract reduced exosome secretion by downregulating Rab27a and nSMase2 across three breast-cancer cell lines ^{46Reference 46Gupta S et al et al. · 2025In vitroRole of Acorus calamus extract in reducing exosome secretion by targeting Rab27a and nSMase2: a therapeutic approach for breast cancer — in vitroView study →}.

A review treats asarone-based chemoprevention as a hypothesis rather than an established effect ^{54Reference 54Das BK et al et al. · 2019ReviewExperimental evidence for use of Acorus calamus (asarone) for cancer chemoprevention — reviewView study →}. The findings so far involve scattered targets, small studies and isolated fractions.

β-Asarone. The main safety concern is β-asarone, a phenylpropene that is genotoxic and carcinogenic in rodents, causing liver and small-intestine tumours through a liver epoxide metabolite ^{47,5,4Reference 47Cartus AT et al et al. · 2015In vitroHepatic metabolism of carcinogenic β-asarone — in vitroView study →Reference 5Chellian R et al et al. · 2017ReviewPharmacology and toxicology of α- and β-Asarone: A review of preclinical evidence — reviewView study →Reference 4Uebel T et al et al. · 2021ReviewUebel T et al. (2021). α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation — review. J Appl Toxicol. https://pubmed.ncbi.nlm.nih.gov/33236787/View study →}. Regulators have restricted β-asarone and calamus preparations on this basis ^{4Reference 4Uebel T et al et al. · 2021ReviewUebel T et al. (2021). α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation — review. J Appl Toxicol. https://pubmed.ncbi.nlm.nih.gov/33236787/View study →}, and calamus is banned as a food additive in the United States.

Type of plant. β-Asarone follows the plant’s ploidy. Diploid rhizome from United States wetlands measured 0.2% β-asarone by weight, against 4.4% in commercial Indian rhizome ^{51Reference 51Hanson KM et al et al. · 2005In vitroRapid assessment of beta-asarone content of Acorus calamus by micellar electrokinetic capillary chromatography — in vitroView study →}, and tetraploid oil can be 70–96% β-asarone ^{58Reference 58Szczeblewski P et al. · 2022The role of centrifugal partition chromatography in the removal of β-asarone from Acorus calamus essential oil — analytical, Scientific reports, 12. https://pubmed.ncbi.nlm.nih.gov/36564541/View study →}. Low-asarone diploid or triploid rhizome is the material recommended for use ^{16Reference 16Keller K et al et al. · 1985In vitroSpasmolytische wirkung des isoasaronfreien kalmus1 — in vitroView study →}.

Other constituents. α-Asarone is carcinogenic in male mice and probably genotoxic ^{48Reference 48Cartus AT et al et al. · 2016In vitroMetabolism of the carcinogen alpha-asarone in liver microsomes — in vitroView study →}, and methyl eugenol is a recognised rodent carcinogen. A 2025 OECD-guideline Ames test on Indian rhizome and β-asarone was negative for bacterial mutagenicity. This does not overturn the rodent carcinogenicity data, but suggests the mechanism is not simple point mutation ^{49Reference 49Narayana DBA et al et al. · 2025In vitroReporting negative Ames test results for Indian Acorus calamus L., rhizome, extracts, and beta asarone — in vitroView study →}.

Essential oil. Between 2003 and 2006 the Swedish Poisons Information Centre was consulted on 30 cases of intentional intoxication with calamus products sold online as hallucinogens. The main symptom was prolonged vomiting, sometimes lasting more than 15 hours ^{52Reference 52Björnstad K et al et al. · 2009Case reportBioanalytical investigation of asarone in connection with Acorus calamus oil intoxications — human case seriesView study →}.

Antiepileptic drugs. A hydroalcoholic extract potentiated valproate and carbamazepine in rodents, which points to a possible interaction with antiepileptic drugs ^{8Reference 8Katyal J et al et al. · 2012AnimalInteraction of hydroalcoholic extract of Acorus calamus Linn. with sodium valproate and carbamazepine — animal in vivoView study →}. No human drug-interaction or CYP450 studies have been done.