Marshmallow Root

Althaea officinalis L. belongs to Malvaceae, the mallow or hibiscus family, and NCBI Taxonomy files it as taxon 145745. WHO describes a perennial herb with erect, woody stems 60–120 cm high, alternate, velvety, toothed leaves that are oval to slightly heart-shaped and sometimes three-lobed, and pale pink flowers in the leaf axils, followed by a ring of small fruits. Britannica gives flowers about 5 cm across on stalks that can reach about 1.8 metres. WHO lists it as native to Europe and western Asia and naturalized in the United States; Britannica, which places its native range in eastern Europe and northern Africa, notes that it grows mainly in marshy areas near the sea, the origin of the English name. Old names collected by WHO include white mallow, sweet weed, and the French guimauve.

The medicinal part is the root. The European Pharmacopoeia defines marshmallow root as the peeled or unpeeled, whole or cut, dried root, with a swelling index of at least 10, a measure of how much the powdered root swells in water (EMA). Roots are taken in autumn from cultivated plants at least two years old (WHO, EMA). The unpeeled root is greyish-brown and deeply furrowed; peeled root is greyish-white and fibrous, with a faint smell and a mucilaginous taste (WHO). Leaves and flowers also contain mucilage, and the leaf has its own traditional uses, but the EU monograph, the WHO monograph, and almost all research concern the root. Related plants cause confusion: in its 2025 review EMA set aside three papers because they concerned a different species, Althaea rosea, a hollyhock.

Mucilage is the defining constituent. EMA’s assessment report cites a mucilage content of 5–11.6% depending on season, while WHO gives 10–20% and sets a minimum of 10% in peeled root. The mucilage is a mixture of polysaccharides: acidic rhamnogalacturonans whose backbone is made of D-galacturonic acid (PubChem CID 439215, C6H10O7) and L-rhamnose units in equal proportions, along with arabinogalactans, arabans, and glucans. The root also holds about 11% pectin, 25–35% starch, and around 10% sucrose, plus small amounts (0.14–0.28%) of flavonoids such as hypolaetin-8-glucoside (EMA). Traditional preparations extract the mucilage by soaking the cut root in water, either as a cold macerate or as a syrup base.

EMA’s assessment report, drawing on the German pharmacognosist Madaus (1938), says marshmallow has been used in European medicine since ancient times, though ancient descriptions do not always clearly refer to the same plant: Theophrastus described an althaea with yellow flowers and Dioscorides one with rose-red flowers. Hippocrates is said to have recommended a decoction of the root for wounds, and Dioscorides listed uses ranging from failure to pass urine, diarrhoea, and stones to nerve pain, bee stings, and toothache. Later European physicians, including Paracelsus, Lonicerus, and Matthiolus, prescribed it to soften abscesses, as an expectorant and diuretic, and externally for ulcers and burns.

Marshmallow root then became a fixture of official pharmacy. EMA traces continuous documentation through the German pharmacopoeia of 1926, the British Pharmaceutical Codex of 1949, Martindale, the British Herbal Pharmacopoeia of 1983, Germany’s Commission E, the WHO and ESCOP monographs, and the European Pharmacopoeia. Marshmallow syrup (Sirupus althaeae) appears in Austrian, Czechoslovak, Polish, and German pharmacopoeias; the 1949 British version is now considered obsolete because it contained chloroform. One Lithuanian syrup has been on the market for more than 100 years, and a German syrup since at least 1976 (EMA). WHO notes that the root was also added to cough mixtures to mask the taste of bitter drugs. The EU herbal committee adopted its first monograph in May 2009 and revised it on 12 July 2016; a periodic review adopted on 19 November 2025 found no reason to change it.

The sweet is the plant’s most famous legacy. Britannica notes that the root was formerly used to make marshmallows, and in French the same word, guimauve, names both the plant and the confection. Modern marshmallows are made with gelatine rather than root: Clarebrough and colleagues (Colorectal Disease 2015) tested the folk belief that eating marshmallows thickens ileostomy output, and attributed the plausible mechanism to the gelatine they contain. In their crossover trial, 28 people with ileostomies who ate three marshmallows three times a day for a week had a median reduction in output of 75 ml a day. That is a property of the confectionery, not of Althaea. Marshmallow root itself is still used as a flavouring in food (EMA), and LactMed notes that the FDA considers marshmallow generally recognized as safe in food amounts.

Marshmallow root works mainly by physical means. WHO attributes its demulcent effect to its high content of polysaccharide hydrocolloids, which form a protective coating on the lining of the mouth and throat and soothe local irritation. EMA notes that the only non-clinical study directly supporting this is an experiment in which purified root polysaccharides adhered moderately, in a concentration-dependent way, to isolated pig cheek lining. Deters and colleagues (Journal of Ethnopharmacology 2010) found that an aqueous root extract stimulated the viability and growth of human epithelial cells in culture, and that the polysaccharides were taken up into epithelial cells and formed adhesive layers on other cells, which the authors linked to tissue repair. These are laboratory findings; no human study has measured how long the coating lasts or what it does to healing.

Animal studies support a cough-suppressing effect. EMA summarizes work in cats in which oral root extract and isolated mucilage reduced mechanically induced coughing, less than codeine but more than two non-narcotic cough drugs. Šutovská and colleagues (Bratislava Medical Journal 2011) found that rhamnogalacturonan from the root suppressed citric-acid-induced cough in guinea pigs in a dose-dependent way, with the higher dose comparable to codeine, without widening the airways; the effect was shorter-lived in animals with allergic airway inflammation. A related study pointed to serotonin 5-HT2 receptors rather than bronchodilation (EMA). Whether these effects occur at human doses has not been tested.

Other laboratory signals are inconsistent. Isolated mucilage injected into mice lowered blood glucose for several hours, and mucilage stimulated immune cells in mice; a 20% root ointment reduced skin irritation in rabbits, but less than dexamethasone, while an oral alcoholic extract had no anti-inflammatory effect in rats (EMA, WHO). EMA concluded that these results cannot be related directly to clinical use. The interaction warning comes from the same physical property: a mucilage layer in the gut could delay absorption of other medicines, though EMA notes this has never been tested in animals or people.

Mouth and throat irritation with dry cough is the main use, and the evidence is observational. In a post-marketing study (Fasse and colleagues, 2005, reviewed by EMA), 313 children aged 3 months to 12 years with throat irritation and dry cough took an aqueous marshmallow root syrup, 2.5–10 ml four to six times daily, mostly for three days. Physicians and parents rated efficacy very good or good in 84% and tolerability very good or good in 97%. In a retrospective review by 53 physicians (Bässler, 2005), 599 children treated for up to two weeks were rated very good or good in over 90%, with no adverse effects recorded. EMA notes that neither study was randomized or controlled and that no objective measures were made, so they support only traditional use.

Adult evidence is scarcer. EMA describes a double-blind trial by Rouhi and Ganji (2007) in 63 Iranian patients with dry cough caused by ACE inhibitor blood pressure drugs: those taking marshmallow drops, 20 drops three times daily for four weeks, saw their cough score fall from 2.66 to 1.23 on a 0–4 scale, against 2.7 to 2.33 with placebo. EMA could not count it as proof because the preparation was not described. Fink and colleagues (Complementary Medicine Research 2018) surveyed 822 pharmacy customers who bought marshmallow root lozenges or syrup for dry cough and reported rapid relief, often within 10 minutes, with three minor adverse events; EMA’s 2025 review dismissed the surveys as uncontrolled and based only on users’ impressions. A 2020 review by Mahboubi, of the medicinal plants research department of an Iranian pharmaceutical company, concluded that marshmallow is effective for dry cough, especially in combinations, but EMA found it added no new clinical data.

Combination products have the best-controlled data, but cannot isolate marshmallow’s contribution. Brinckmann and colleagues (Journal of Alternative and Complementary Medicine 2003) randomized 60 adults with acute pharyngitis to Throat Coat, a tea containing slippery elm, licorice, and marshmallow root, or a placebo tea. Pain on swallowing fell significantly more with the herbal tea from 5 to 30 minutes after drinking (sum of pain intensity difference −43.8 versus −16.5). The first author worked for the tea’s manufacturer. EMA also notes a liquid combination of marshmallow root and thyme registered in several EU countries for cough.

Mild stomach and gut discomfort is the second traditional EU indication, but EMA states that no clinical data exist for it. WHO lists gastric irritation, along with asthma, cystitis, and dysentery, as folk uses not supported by experimental or clinical data, and the 1983 British Herbal Pharmacopoeia recommended the root for gastritis and peptic ulcer (EMA). LactMed notes that marshmallow is promoted to increase breast milk supply and is in some proprietary mixtures for that purpose, but no scientifically valid clinical trials support this. WHO also records traditional external use as an emollient for wounds and dry skin, which the EU monograph does not cover.

EU traditional use for mouth or throat irritation and dry cough (EMA/HMPC/436679/2015, adopted 12 July 2016): cut root as a macerate, made by soaking in 150 ml of water and used immediately; adolescents and adults 0.5–3 g several times daily, up to 15 g a day; children 6–11 years 0.5–1.5 g three times daily; children 3–5 years 0.5–1 g three times daily. Syrup made from a macerate: adults 10–15 ml three to five times daily; children 6–11, 5 ml three to five times daily; children 3–5, 5 ml up to four times daily. An aqueous liquid extract, dry extracts such as lozenges (not under 6 because of the dosage form), and, for adults only, a 25% ethanol liquid extract at 2–5 ml three times daily are also listed. Preparations can be swallowed or held in the mouth. Not recommended under 3. If symptoms last longer than a week, see a doctor.

EU traditional use for mild gastrointestinal discomfort: adolescents and adults, 2–5 g of cut root in 150 ml of water as a macerate three times daily, up to 15 g a day; not recommended under 12; see a doctor if symptoms last longer than two weeks (EMA). Commission E, quoted by EMA, gave 6 g of root a day and described the traditional cold maceration: 2–5 g in 150 ml of cold water for 30 minutes with frequent stirring, then strained and warmed before drinking, up to three times a day. WHO gives similar doses, 0.5–3 g as a cold macerate or 2–8 ml of syrup for cough and throat irritation, and 3–5 g up to three times daily for gastric irritation.

Practical points: take marshmallow root at least half an hour to an hour apart from other medicines (EMA). Traditional syrups are mostly sugar; German and Austrian pharmacopoeial recipes cited by EMA dissolve roughly 1.6–1.8 parts of sucrose in each part of macerate, which matters for people with diabetes and for children’s teeth. Alcoholic extracts must be labelled for ethanol content (EMA). Choose products made to pharmacopoeial standards; EMA notes that the root can be identified unambiguously, but its 2025 review included two papers examining lead and cadmium in marshmallow root preparations, a reminder that sourcing matters.