Introduction

A perennial herb, marshmallow is native throughout damp areas of Europe and Western Asia. Marshmallow is naturalized in North America in salt marshes from Massachusetts to Virginia, and it’s cultivated from Western Europe to Russia.^1,2,3 Its material of commerce consists of both the whole or cut dried leaves and the peeled or unpeeled, whole or cut, dried roots.⁴ These materials are harvested from cultivated plants mainly from Belgium, Bulgaria, Croatia, Hungary, Russian Federation, and Serbia.^3,5 The therapeutic activity of high-mucilage-containing materials, like marshmallow, can be predicted in part by volumetrically measuring their swelling index. This quality indicating test directly corresponds to the demulcent action (i.e., the soothing of mucous membranes caused by the expansion of mucilage polysaccharides when they absorb moisture, swell, and form a demulcent gel that has bioadhesive properties). Pharmacopeial quality marshmallow root should have a swelling index of not-less-than 10, and for marshmallow leaf, not-less-than 12.⁴ The material used in the traditional systems of medicine in India, the mature dried seeds and roots, are often cultivated in Punjab and Kashmir.^6,7 The plant should be at least two years old before harvesting its roots.⁸ The seeds are collected when they are mature, before the dried fruits fall to the ground.⁶

History and Cultural Significance

Reportedly, marshmallow has been used in traditional European medicine for over 2000 years.² Its therapeutic use was first recorded in the 9^th century BCE, and it was used widely in Greek medicine.⁹ Its genus name Althaea comes from the Greek altho, meaning to cure, and its family name, Malvaceae, is derived from the Greek malake, meaning soft.¹⁰ The root is often used as a component of preparations intended for the treatment of coughs (e.g., teas and syrups).¹¹

Marshmallow’s use in traditional Greek medicine spread to Arabian medicine and to traditional Indian Ayurvedic and Unani medicines.¹ Early Arab physicians prepared a poultice with the leaves to suppress inflammation. The Ayurvedic Pharmacopoeia of India (2006) reports the therapeutic uses of the roots and/or seeds for treating coughs and bronchitis, coryza (runny nose), and throat disorders, among other conditions. An important formulation that contains both marshmallow seed and root, “Gojihvadi Kvath,” indicated for cough, is listed in the Government of India’s Essential Ayurveda Drugs for Dispensaries and Hospitals.¹² In the Unani system of medicine, marshmallow seed is used for treatment of bronchitis, pleurisy, pneumonia, and kidney stones.⁶ The Unani formulation, “Lauq-e-Sapistan,” is indicated for dry and irritative cough, scanty sputum, chronic bronchitis, and chronic catarrh. Lauq-e-Sapistan is a soft, honey-based compound medicine with powdered marshmallow seed, snap melon seed (Cucumis melo, var. momordica, Cucurbitaceae), jujube fruit (Ziziphus jujuba, Rhamnaceae), and quince fruit (Cydonia oblonga, Rosaceae), among other herbs.¹³

The sweet confection known as “marshmallow” is related to the plant through history. In 2000 BCE, ancient Egyptians reportedly made a candy of marshmallow root and honey, which was reserved for gods and royalty.¹⁴ In the more recent past (circa mid-17^th century CE), French druggists made a meringue of marshmallow root extract, egg white, and sugar called Pâté de Guimauve to treat chest complaints.¹⁰ By the late 19^th century, marshmallow confections were easily available to the public, mass-produced, and no longer contained marshmallow extract.¹⁴

In 1989, the German Commission E approved both marshmallow leaf and root for irritation of the oral and pharyngeal (throat) mucosa and associated dry cough.¹⁵ The root was also approved for mild inflammation of the gastric mucosa (stomach lining). The German Standard License for marshmallow leaf or root teas indicates their use to alleviate irritation of the mucous membranes of the mouth and throat accompanied by dry irritated cough, and for mild inflammation of the gastric mucosa.³ As all national pharmacopeias and formularies of European Community member states are in the process of harmonization, a European Community Herbal Monograph for marshmallow root is in development. This monograph will eventually become official in all 27 member states for the purpose of uniform product licensing and labeling for drug preparations containing marshmallow root.¹⁶

The non-official British Herbal Compendium, 1^st edition, indicates marshmallow root internally for soothing the stomach and intestinal tract.⁸ Topically, liquid preparations made from marshmallow root are indicated as a mouthwash or gargle for soothing inflammations in the mouth and throat.⁸

For marshmallow leaf, the British Herbal Compendium, 2^nd edition, states that no indications are adequately substantiated by pharmacological or clinical studies. However, uses based on experience or tradition include internal use of the tea infusion or liquid extract for irritation and inflammation of the oral and pharyngeal mucosa, dry irritating coughs, respiratory catarrh and bronchitis, digestive tract disorders (peptic ulcer), and urinary tract disorders (cystitis).¹⁷

Similarly, the European Scientific Cooperative on Phytotherapy (ESCOP) indicates marshmallow aqueous cold macerate or syrup for dry cough and irritation of the oral or pharyngeal (throat), and the cold macerate form for gastrointestinal irritation.¹⁸ However, the World Health Organization (WHO) monograph states that medicinal uses for marshmallow root are not supported by clinical data. For uses described in pharmacopeias and in traditional systems of medicine, the WHO lists the same aforementioned indications citing the monographs of the British Herbal Compendium, ESCOP, and the German Commission E.¹⁹

In the United States, marshmallow leaves and roots are used as components of herbal teas, dietary supplement products, and topical demulcent preparations.¹¹ Marshmallow flower and root, and extracts thereof, are also classified by the Food and Drug Administration (FDA) as generally recognized as safe (GRAS) natural flavoring substances when used in the minimum quantity required to produce this intended effect.²⁰

Modern Research

In a pharmacological study involving male and female adult cats with mechanically induced cough, a mucilage polysaccharide extractive of marshmallow flowers demonstrated significantly higher antitussive activity than the non-narcotic drug dropropizine (frequently prescribed for cough treatment). However, it showed somewhat lower activity than the narcotic drug codeine, and whereas codeine had a negative impact on expectoration, marshmallow mucilage was shown to be an effective antitussive with no negative impact on expectoration. No adverse effects were observed in the marshmallow group.²¹

In a randomized, placebo controlled study involving 63 patients who had developed dry cough while taking angiotensin-converting enzyme (ACE) inhibitor drugs, patients received a liquid preparation of marshmallow root or placebo. The marshmallow group showed a significant reduction in cough score compared to placebo.²²

An open-label clinical study containing 42 patients with chronic cutaneous leishmaniasis (CCL) involved the application of an herbal paste to lesions. The herbal paste was prepared from a special extract designated as “Z-HE,” which was modified from a traditional Iranian medicine formula. The Z-HE extract contained extractives of marshmallow and the related hollyhock (A. rosea) (plant parts not specified in study), as well as other herbs. The study reported that 69% had a complete cure, 12% had partial cure, and 19% failed to respond to the therapy. In a subsequent open-label trial, the authors concluded that although the active ingredient(s) and the mechanism(s) of action of Z-HE are not known, its ease of preparation, topical application, lack of adverse effects, low cost, and satisfactory cosmetic effects make it a promising drug for use in the treatment of lesions of CCL.²³

An open-label clinical study containing 62 patients with irritating cough used a combination syrup (Weleda Hustenelixier, Weleda, Schwäbisch Gmünd, Germany) containing extracts of English ivy leaf (Hedera helix, Araliaceae), thyme leaf and wild thyme leaf (Thymus vulgaris and T. serpyllum, Lamiaceae), anise fruit (Pimpinella anisum, Apiaceae), and marshmallow root. The syrup alleviated coughs resulting from the common cold, bronchitis, and respiratory tract diseases that formed mucous.²⁴

A double-blind, placebo-controlled study contained 60 patients diagnosed with acute pharyngitis. The patients were treated with an herbal tea (Throat Coat®, Traditional Medicinals, Sebastopol, CA) that contained marshmallow root, licorice root (Glycyrrhiza glabra, Fabaceae), slippery elm bark (Ulmus rubra, Ulmaceae), and wild cherry bark (Prunus serotina, Rosaceae), among others. The tea was found to be significantly superior to placebo and provided a rapid, temporary relief of sore throat pain.²⁵

Future Outlook

Wild marshmallow is considered a threatened plant in Germany and is listed in the German Federal Ordinance on the Conservation of Species.²⁶ A permit is necessary for import or export of any wild-collected material. Marshmallow is also listed as “nationally scarce” in the United Kingdom,²⁷ and due to its scarcity in Bulgaria, it is prohibited from collection in the wild.²⁸ Commercial marshmallow is, and should continue to be, harvested only from cultivated plants, especially when the root is being sought.

—Gayle Engels

References

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