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Limited evidenceImmunity

Marshmallow Root

Marshmallow root's mucilage forms a soothing film over an irritated throat, which is a plausible mechanism but has never been tested against placebo in a proper randomized trial. It is safe and cheap, and probably worth about what a cup of honey-lemon tea is worth.

What the science says

  • Soothes dry, irritative cough and sore throat Limited evidence

    The root contains 5-11% polysaccharide mucilage that coats pharyngeal mucosa and physically blunts the cough reflex — a real mechanism, confirmed by bioadhesion assays. But the human evidence is two uncontrolled user surveys of a marshmallow syrup (n=822 and n=396) in which 86-95% of respondents rated it effective. Cough placebo response rates in controlled trials routinely run 60-85%, so uncontrolled satisfaction data like this cannot distinguish drug from expectation.

  • Anti-inflammatory action on mucosal tissue Limited evidence

    Aqueous marshmallow root extract inhibits human hyaluronidase-1 and reduces inflammatory mediator release in cultured macrophages at concentrations of roughly 0.1-1 mg/mL. These are cell-culture findings; no trial has measured inflammatory markers or mucosal healing in people taking marshmallow.

  • Helps gastritis, reflux, or 'leaky gut' Limited evidence

    A demulcent that coats the throat during a 10-second swallow is not established to coat the stomach or intestine, and no controlled trial has tested marshmallow root for gastritis, GERD, or intestinal permeability. The European Medicines Agency lists marshmallow root only as a 'traditional use' herbal, meaning efficacy is assumed from long use rather than demonstrated.

Dosage & safety

Studied doseTraditional and monograph doses: 2-5 g dried root as a cold-water infusion (cold maceration preserves mucilage better than boiling), up to 3 times daily; syrups typically 10 mL up to 6 times daily; lozenges around 20 mg dry extract. No dose-response data from controlled trials exist because those trials have not been done.
SafetyVery well tolerated; the main documented issue is pharmacokinetic rather than toxic. Mucilage can coat the gut and delay absorption of other oral medications, so take other drugs at least 30-60 minutes before or after. Syrups are often sugar-heavy — relevant for diabetics. Theoretical additive effect with blood-glucose-lowering drugs has been raised but not documented in humans. Not banned in sport; no hepatotoxicity signals.

Scientific references

Where to buy

Nature's Answer, Marshmallow Root Fluid Extract, Alcohol-Free, 2,000 mg, 1 fl oz (30 ml)

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