Antispasmodic

In animals, unripe-fruit extract antagonised acetylcholine-, histamine- and serotonin-induced gut contraction and slowed gastrointestinal transit, alongside reducing castor-oil-induced intestinal fluid accumulation ^{11Reference 11Dhuley JN · 2003Investigation on the gastroprotective and antidiarrhoeal properties of Aegle marmelos unripe fruit extract — [animal]View study →}. Antagonising three receptor pathways at once points to a broad smooth-muscle effect rather than a single receptor block, which fits diarrhoeal cramping, where more than one mediator is at work.

The evidence is animal only, and it is specifically enteric: no bronchial, biliary or uterine tissue has been tested.

The one human study, a placebo-controlled crossover in 12 volunteers, showed a dry extract prolongs gastrointestinal transit ^{12Reference 12Gotteland et al. · 1995RCTEffect of a dry boldo extract on oro-cecal intestinal transit in healthy volunteers — randomised, placebo-controlled crossover trialView study →}.

It is a slowing effect on gut motility, consistent with smooth-muscle relaxation rather than with digestive stimulation.

Butterbur was given for spasmodic complaints, colic, cramping and spasmodic cough, and that strand of the tradition is the one the modern pharmacology supports.

In rat aortic smooth-muscle cells, iso-S-petasin blocked L-type voltage-dependent calcium channels, and petasin produced endothelium-independent vasorelaxation by lowering cytosolic calcium ^{97,98Reference 97Wang et al. · 2002In vitroCa2+ channel blocking effect of iso-S-petasin in rat aortic smooth muscle cells — in vitroView study →Reference 98Wang et al. · 2010In vitroCellular calcium regulatory machinery of vasorelaxation elicited by petasin — in vitro / animalView study →}. The same calcium antagonism plausibly explains the cerebral-vessel and bronchial effects behind its migraine and asthma use.

Every spasmolytic result is from isolated tissue or animal models. No human trial has measured a spasmolytic endpoint directly.

Forskolin activates adenylate cyclase without touching the β-receptor, so it raises cAMP regardless of receptor sensitivity.

In a randomised, double-masked, placebo-controlled crossover in asthmatics, inhaled dry-powder forskolin (colforsin) significantly increased airway conductance, comparably to fenoterol ^{21Reference 21Bauer K et al. · 1993RCTPharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma — [randomised, placebo-controlled trial]View study →}. In sensitised guinea pigs forskolin prevented antigen-induced bronchospasm while blocking leukotriene and histamine release ^{22Reference 22Kreutner W et al. · 1985AnimalBronchodilator and antiallergy activity of forskolin — [animal model]View study →}.

An oral trial also exists. Forskolin at 10 mg/day reduced the proportion of patients having asthma attacks versus inhaled cromoglycate over six months, though the trial was small and single-blinded ^{23Reference 23González-Sánchez R et al. · 2006RCTForskolin versus sodium cromoglycate for prevention of asthma attacks: a single-blinded clinical trial — [randomised controlled trial]View study →}, and a rodent study found a coleus root and leaf extract eased cough and airway remodelling ^{24Reference 24Ma C et al. · 2019AnimalExtracts of Coleus forskohlii relieves cough and asthma symptoms via modulating inflammation and the extracellular matrix — [animal model]View study →}.

The fenoterol-comparable result is an inhaled isolated molecule, which the root taken by mouth does not reproduce. The action is bronchial: no gut or uterine smooth-muscle data exist for the herb.

Two spasmolytic constituents were isolated from Viburnum itself: viopudial, described in 1972 as a hypotensive smooth-muscle antispasmodic ^{25Reference 25Nicholson et al. · 1972Viopudial, a hypotensive and smooth-muscle antispasmodic from Viburnum opulus — animal/isolated tissueView study →}, and the coumarin scopoletin, identified in 1967 as an antispasmodic component of V. opulus and V. prunifolium ^{26Reference 26Nicholson et al. · 1967In vitroScopoletin, an antispasmodic component of Viburnum opulus and prunifolium — in vitroView study →}. Scopoletin inhibits intracellular calcium mobilisation non-specifically in isolated rat aorta ^{27Reference 27Oliveira et al. · 2001In vitroIntracellular calcium mobilisation as a target for the spasmolytic action of scopoletin — in vitro (rat aorta)View study →}, with calcium-channel-blocking activity confirmed in airway smooth muscle ^{28Reference 28Patel et al. · 2013In vitroBronchodilatory mechanism and identification of scopoletin as the active calcium-channel-blocking ingredient — in vivo/in vitroView study →}.

The effect is a weak, non-selective calcium effect from two constituents present at unquantified levels in the bark, demonstrated in isolated aorta and trachea. No uterine or skeletal-muscle tissue has been studied, and there is no modern controlled trial of any whole cramp-bark preparation for dysmenorrhea or cramp.

The one registered dysmenorrhea trial used a homeopathic 3X dilution (NCT02467543).

Practitioners rate it a reliable but gentle relaxant.

Classic isolation work identified butylidenephthalide as an antispasmodic that inhibited uterine contractions induced by prostaglandin F2α, oxytocin and acetylcholine, three unrelated stimulants, so the relaxation is not receptor-specific. It relaxed smooth muscle generally, though less potently than papaverine ^{29Reference 29Ko · 1980A newly isolated antispasmodic — butylidenephthalide (isolated-tissue / comparative study)View study →}.

The effect is shared with Z-ligustilide, consistent with the root’s phthalide-rich essential oil ^{30Reference 30Wei et al. · 2016ReviewAngelica sinensis in China — a review of botanical profile, ethnopharmacology, phytochemistry and chemical analysis — reviewView study →}.

The data are isolated rat uterus and guinea-pig ileum from 1980, essentially unreplicated, and there is no controlled human dysmenorrhea trial of dong quai as a single herb. The phthalides are poorly bioavailable by mouth, so a decoction or 1:2 tincture is unlikely to reach the bath concentrations used ex vivo.

Estafiate shows direct smooth-muscle relaxant activity, which supports both its antidiarrhoeal use and the traditional Mexican application for colic and menstrual cramps.

The target has not been identified, and there is no human trial.

The relief of colicky biliary pain in the controlled trial ^{20Reference 20Niederau C · 1999RCTThe effect of chelidonium- and turmeric root extract on upper abdominal pain due to functional disorders of the biliary system — a placebo-controlled double-blind randomised studyView study →} is the antispasmodic component of greater celandine’s action, attributed to the alkaloids coptisine and protopine. Chelidonine relaxes isolated ileum by a papaverine-like musculotropic action, with protopine the stronger of the two on nerve-stimulated contraction ^{1Reference 1Hiller KO et al. · 1998Antispasmodic and relaxant activity of chelidonine, protopine, coptisine, and Chelidonium majus extracts on isolated guinea-pig ileum — ex vivo/animalView study →}.

The clinical result comes from a combination product, and no smooth-muscle endpoint has been measured for the herb alone.

Gumweed entered the US Pharmacopoeia in the nineteenth century as an antispasmodic and expectorant for asthma and bronchitis. The airway relaxation pairs with its anti-inflammatory work, the combination an asthma herb needs.

The spasmolysis has not been measured directly, and there is no human trial.

Kavain and methysticin inhibit voltage-operated Na⁺ channels in rat CA1 hippocampal neurons and in synaptosomes ^{51,52Reference 51Gleitz et al. · 1995In vitroGleitz, J., Beile, A., & Peters, T. (1995). (±)-Kavain inhibits veratridine-activated voltage-dependent Na⁺ channels in synaptosomes [in vitro]. Neuropharmacology. https://pubmed.ncbi.nlm.nih.gov/8532183/View study →Reference 52Magura et al. · 1997AnimalKava extract ingredients (+)-methysticin and (±)-kavain inhibit voltage-operated Na⁺-channels in rat CA1 hippocampal neurons [animal]View study →}, and reduce depolarisation-evoked calcium influx and glutamate release ^{52Reference 52Magura et al. · 1997AnimalKava extract ingredients (+)-methysticin and (±)-kavain inhibit voltage-operated Na⁺-channels in rat CA1 hippocampal neurons [animal]View study →}. That explains the muscle-relaxant and spasmolytic effects observed in the animal pyrone work of the 1960s to 1990s, where methysticin showed spasmolytic activity directly.

The case is animal and in-vitro, and no human antispasmodic trial exists. The muscle-tension relief people report is plausibly downstream of general relaxation rather than a direct effect on muscle.

Linalyl acetate relaxed isolated rat uterine smooth muscle ^{53Reference 53Koto et al. · 2006In vitroLinalyl acetate as a major ingredient of lavender essential oil relaxes the rabbit/rat smooth muscle — in vitro/animal modelView study →}, and classic mode-of-action work showed lavender oil relaxes guinea-pig and rat preparations through a non-specific, cyclic-AMP-mediated spasmolytic effect ^{54Reference 54Lis-Balchin et al. · 1999In vitroStudies on the mode of action of the essential oil of lavender (Lavandula angustifolia) — in vitro smooth-muscle studyView study →}. Culpeper gave lavender for “cramps, convulsions, palsies”.

The work is ex-vivo tissue and animal. No clinical trial has tested lavender for menstrual, gut or any other spasm.

Houpo is a canonical Chinese remedy for abdominal distension, bloating and diarrhoea ^{55Reference 55Luo et al. · 2019ReviewA review of the phytochemistry and pharmacological activities of Magnoliae officinalis cortex — reviewView study →}. In isolated intestinal tissue, magnolol and honokiol relax smooth muscle by acting on the TRPC4 channel to reduce extracellular calcium influx ^{56Reference 56Niu et al. · 2022In vitroMagnolol and honokiol target TRPC4 to regulate extracellular calcium influx and relax intestinal smooth muscle — in vitro / ex vivoView study →}.

A rat model of diarrhoea-predominant IBS reported that magnolol, honokiol and obovatol improved GI motility, intestinal permeability and inflammatory cytokines ^{57Reference 57Wang et al. · 2026AnimalDeciphering the multi-target mechanism of Magnolia officinalis in irritable bowel syndrome with diarrhea — network pharmacology, machine learning and in vivo (rat) validationView study →}, though that study leaned on network pharmacology and molecular docking rather than direct measurement.

No controlled human trial exists in functional GI disorders, the herb’s strongest traditional use.

Small doses of the dried plant for menstrual cramping and spasmodic pain are the plant’s principal historical action, recorded consistently across North American and European practice.

No study of this species addresses spasm, and the mechanism is unresolved.

The evidence is isolated-tissue work in which harmaline and the related harmala alkaloids blocked voltage-gated calcium channels in vascular and intestinal smooth muscle ^{59Reference 59Karaki et al. · 1986In vitroInhibition of calcium channels by harmaline and other harmala alkaloids in vascular and intestinal smooth muscles — in vitroView study →}.

Harmane and harmine are present at very low concentrations in P. incarnata, so whether the plant delivers enough to produce this effect at ordinary doses is unresolved. The mechanism is secure and the dose relevance uncertain.

Classic work showed paeoniflorin blocks transmission at the neuromuscular junction in frog and mouse preparations when blended with glycyrrhizin from licorice, the pharmacological basis of the peony–licorice synergy ^{60Reference 60Kimura et al. · 1984In vitroBlocking effects of blended paeoniflorin or its related compounds with glycyrrhizin on neuromuscular junctions in frog and mouse — in vitro/animalView study →}. A randomised trial in painful muscle cramps from lumbar spinal stenosis found Shakuyaku-kanzo-to effective and established a minimum effective dose ^{61Reference 61Takao et al. · 2015RCTShakuyaku-kanzo-to (Shao-Yao-Gan-Cao-Tang) as treatment of painful muscle cramps in patients with lumbar spinal stenosis and its minimum effective dose — randomised controlled trialView study →}.

The crude root also carries analgesic activity in animal pain models ^{62Reference 62He et al. · 2011ReviewAnti-inflammatory and immunomodulatory effects of Paeonia lactiflora Pall., a traditional Chinese herbal medicine — reviewView study →}, and albiflorin accompanies paeoniflorin in the root ^{63Reference 63Tan et al. · 2020ReviewEfficacy, chemical constituents, and pharmacological actions of Radix Paeoniae Rubra and Radix Paeoniae Alba — reviewView study →}.

The effect as evidenced is a two-herb effect. The trial dose is 2.5–7.5 g/day of the combined formula, the mechanism paper tests the blend, and peony alone has no controlled human antispasmodic evidence.

In isolated rat trachea, thyme extract relaxed airway smooth muscle and inhibited endothelin-induced contraction, an effect carried by the whole extract rather than thymol alone ^{86Reference 86Engelbertz et al. · 2008AnimalThyme extract, but not thymol, inhibits endothelin-induced contractions of isolated rat trachea — ex vivoView study →}. The companion high- and low-thymol comparison localised part of the relaxation to β2 receptors ^{87Reference 87Begrow et al. · 2010Impact of thymol in thyme extracts on antispasmodic action and ciliary clearance — animal ex vivo studyView study →}, and the essential oil of an Ethiopian Thymus species produced concentration-dependent tracheal relaxation with a defined mechanism ^{88Reference 88Rehman et al. · 2021In vitroTracheal relaxant and antimicrobial effects of the essential oil of an Ethiopian thyme species — in vitro / ex vivoView study →}.

There is no human spirometry or bronchodilation trial of thyme. The effect needs whole-extract or standardised-phenol material, and it is respiratory-specific: no gut or uterine tissue has been tested.

A double-blind RCT (n=100, 255 mg three times daily for the first three days of menstruation over two cycles) found significantly greater pain reduction than placebo, credited to the antispasmodic action ^{92Reference 92Mirabi P · 2011Effects of valerian on the severity and systemic manifestations of dysmenorrheaView study →}. A 2025 systematic review pooled five controlled trials (201 intervention / 207 control) for a large effect on menstrual pain (SMD −1.03, 95% CI −1.74 to −0.33) ^{93Reference 93Rabiei F et al. · 2025Meta-analysisEffect of Valeriana officinalis on Primary Dysmenorrhea: A Systematic Review and Meta-AnalysisView study →}.

That review reports very high heterogeneity (I²=90%) across few, small, largely single-region trials. No study measures spasmolysis, and neither dysmenorrhea trial assayed the valepotriate or volatile-oil content the effect is attributed to.

The valepotriates are the herb’s least stable constituent class, so a stored or aged product may not carry them.