Demulcent herbs soothe mucous membranes of the respiratory and digestive tract and include aloe, slippery elm, licorice root, and marshmallow.
The listings of research below represents a compilation of scientific articles found on the topic, with a very brief overview description of each article/study. This compilation of research articles does not necessarily imply that there are adequate results to demonstrate safe and/or effective human use of any herb listed.
In a double blind study, A. officinalis reduced the cough of those taking and having side effects from enzyme inhibitor drugs to treat hypertension. Rouhi, H., & Ganji, F. (2007). Effect of Althaea officinalis on cough associated with ACE inhibitors. Pakistan Journal of Nutrition, 6(3), 256-258.
In an open trial of 62 patients, a cough syrup made from ivy leaves, thyme herb, aniseed and marshmallow root was effective. From: Büechi, S., Vögelin, R., von Eiff, M. M., Ramos, M., & Melzer, J. (2005). Open trial to assess aspects of safety and efficacy of a combined herbal cough syrup with ivy and thyme. Complementary Medicine Research, 12(6), 328-332.
Oral mucositis was successfully treated with chamomile. From: Mazokopakis, E. E., Vrentzos, G. E., Papadakis, J. A., Babalis, D. E., & Ganotakis, E. S. (2005). Wild chamomile (Matricaria recutita L.) mouthwashes in methotrexate-induced oral mucositis. Phytomedicine, 12(1), 25-27.
Neck and cancer patients who received radiation had delayed onset of mucositis and reduced pain and oral symptoms from gargling a blend with manuka and kanuka. From: Maddocks-Jennings, W., Wilkinson, J. M., Cavanagh, H. M., & Shillington, D. (2009). Evaluating the effects of the essential oils Leptospermum scoparium (manuka) and Kunzea ericoides (kanuka) on radiotherapy induced mucositis: a randomized, placebo controlled feasibility study. European Journal of Oncology Nursing, 13(2), 87-93.
This study demonstrated that 1000 mg of burdock of burdock essence taken orally three times a day after meals helped against H. pylori infection and in gastric mucosal repair in those with gastric ulcers. From: Wu, Y. C., Lin, L. F., Yeh, C. S., Lin, Y. L., Chang, H. J., Lin, S. R., … & Lee, S. C. (2010). Burdock essence promotes gastrointestinal mucosal repair in ulcer patients. Fooyin Journal of Health Sciences, 2(1), 26-31. Anise significantly inhibited gastric mucosal damage induced by necrotizing agents in rats. From: Alhaider, A. A., Al-Moqh, I. A., Mossa, J. S., Al-Soohaibani, M. O., & Rafatullah, S. (2007). Aqueous suspension of anise” Pimpinella anisum” protects rats against chemically induced gastric ulcers. World Journal of Gastroenterology, 13(7), 1112-1118.
Lozenges containing marshmallow root showed an effect in treating irritated oropharyngeal mucosa associated with a dry irritable cough. Benbassat, N., Kostova, B., Nikolova, I., & Rachev, D. (2013). Development and evaluation of novel lozenges containing marshmallow root extract. Pak J Pharm Sci, 26, 1103-1107.
Throat coat, a tea including licorice, slippery elm, and marshmallow, reduced throat pain in patients. From: Brinckmann, J., Sigwart, H., & van Houten Taylor, L. (2003). Safety and efficacy of a traditional herbal medicine (Throat Coat®) in symptomatic temporary relief of pain in patients with acute pharyngitis: A multicenter, prospective, randomized, double-blinded, placebo-controlled study. The Journal of Alternative & Complementary Medicine, 9(2), 285-298.
A combination of celandin, aloevera and psyllium was an effective laxative in constipated patients. From: Odes, H. S., & Madar, Z. (1991). A double-blind trial of a celandin, aloevera and psyllium laxative preparation in adult patients with constipation. Digestion, 49(2), 65-71.
In a double blind study, aloe gel was effective in treating the symptoms of ulcerative colitis. From: Langmead, L., Feakins, R. M., Goldthorpe, S., Holt, H., Tsironi, E., De Silva, A., … & Rampton, D. S. (2004). Randomized, double‐blind, placebo‐controlled trial of oral aloe vera gel for active ulcerative colitis. Alimentary pharmacology & therapeutics, 19(7), 739-747.
An herb formula including slippery elm reduced symptoms of irritable bowels.From: Hawrelak, J. A., & Myers, S. P. (2010). Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. The Journal of Alternative and Complementary Medicine, 16(10), 1065-1071.
Aloe and myrrh reduced stomach ulcer symtoms in human patients. From: Mansour, G., Ouda, S., Shaker, A., & Abdallah, H. M. (2014). Clinical efficacy of new aloe vera‐and myrrh‐based oral mucoadhesive gels in the management of minor recurrent aphthous stomatitis: a randomized, double‐blind, vehicle‐controlled study. Journal of Oral Pathology & Medicine, 43(6), 405-409. Aloe reduced constipation in rats. From: Wintola, O. A., Sunmonu, T. O., & Afolayan, A. J. (2010). The effect of Aloe ferox Mill. in the treatment of loperamide-induced constipation in Wistar rats. BMC gastroenterology, 10(1), 95.
Citrus aurantium and d-limonene promote gastric mucosal healing without any apparent toxic effect in rats. From: Moraes, T. M., Rozza, A. L., Kushima, H., Pellizzon, C. H., Rocha, L. R. M., & Hiruma-Lima, C. A. (2013). Healing actions of essential oils from Citrus aurantium and d-limonene in the gastric mucosa: the roles of VEGF, PCNA, and COX-2 in cell proliferation. Journal of medicinal food, 16(12), 1162-1167.
In constipated rats, aloe was as effective as the laxative drug Gaviscon.From: Ashafa, A. O. T., Sunmonu, T. O., Abass, A. A., & Ogbe, A. A. (2011). Laxative potential of the ethanolic leaf extract of Aloe vera (L.) Burm. f. in Wistar rats with loperamide-induced constipation. Journal of Natural Pharmaceuticals, 2(3), 158-162.
In vitro, marshmallow extracts stimulated epithelial cells to support the traditional use for treatment of irritated mucous membranes. From: Deters, A., Zippel, J., Hellenbrand, N., Pappai, D., Possemeyer, C., & Hensel, A. (2010). Aqueous extracts and polysaccharides from Marshmallow roots (Althea officinalis L.): Cellular internalisation and stimulation of cell physiology of human epithelial cells in vitro. Journal of ethnopharmacology, 127(1), 62-69.
Glycyrrhiza glabra (licorice root) and Adhatoda vasica had an antitussive activity in mice comparable to that of codeine sulphate. From: Jahan, Y., & Siddiqui, H. H. (2012). Study of antitussive potential of Glycyrrhiza glabra and Adhatoda vasica using a cough model induced by sulphur dioxide gas in mice. International journal of Pharmaceutical Sciences and research, 3(6), 1668.
Deglycyrrhizinated licorice reduced gastric mucosal damage in rats. From: Rees, W. D. W., Rhodes, J., Wright, J. E., Stamford, I. F., & Bennett, A. (1979). Effect of deglycyrrhizinated liquorice on gastric mucosal damage by aspirin. Scandinavian journal of gastroenterology, 14(5), 605-607.
Polysaccharides from the roots of Glycyrrhiza glabra were strong anti-adhesives against Helicobacter pylori gastric bacteria invasions. From: Wittschier, N., Faller, G., & Hensel, A. (2009). Aqueous extracts and polysaccharides from liquorice roots (Glycyrrhiza glabra L.) inhibit adhesion of Helicobacter pylori to human gastric mucosa. Journal of ethnopharmacology, 125(2), 218-223.
Glycyrrhiza glabra induced cough efforts in guinea pigs more effectively than codeine. From: Saha, S., Nosál’ová, G., Ghosh, D., Flešková, D., Capek, P., & Ray, B. (2011). Structural features and in vivo antitussive activity of the water extracted polymer from Glycyrrhiza glabra. International journal of biological macromolecules, 48(4), 634-638.
In vivo studies attributed the antitussive effect of coltsfoot to the following constituents: chlorogenic acid, 3,5-dicaffeoylquinic acid, and rutin. From: Li, Z. Y., Zhi, H. J., Zhang, F. S., Sun, H. F., Zhang, L. Z., Jia, J. P., … & Qin, X. M. (2013). Metabolomic profiling of the antitussive and expectorant plant Tussilago farfara L. by nuclear magnetic resonance spectroscopy and multivariate data analysis. Journal of pharmaceutical and biomedical analysis, 75, 158-164.
Flower buds from coltsfoot had an antitussive and expectorant effect on mice. From: Li, Z. Y., Zhi, H. J., Xue, S. Y., Sun, H. F., Zhang, F. S., Jia, J. P., … & Qin, X. M. (2012). Metabolomic profiling of the flower bud and rachis of Tussilago farfara with antitussive and expectorant effects on mice. Journal of ethnopharmacology, 140(1), 83-90.
Marjoram extract reduced gastric ulcers in rats. From: Al-Howiriny, T., Alsheikh, A., Alqasoumi, S., Al-Yahya, M., ElTahir, K., & Rafatullah, S. (2009). Protective Effect of Origanum majorana L.’Marjoram’on various models of gastric mucosal injury in rats. The American journal of Chinese medicine, 37(03), 531-545.
Tea tree oil showed action against Candida albicans and maybe useful in treating fungal mucosal and cutaneous infections. From: D’auria, F. D., Laino, L., Strippoli, V., Tecca, M., Salvatore, G., Battinelli, L., & Mazzanti, G. (2001). In vitro activity of tea tree oil against Candida albicans mycelial conversion and other pathogenic fungi. Journal of chemotherapy, 13(4), 377-383.
Gallic acid, a polyphenolic compound in certain plants, significantly prevented and healed induced gastric injury of gastric mucosal cells in vivo. From: Pal, C., Bindu, S., Dey, S., Alam, A., Goyal, M., Iqbal, M. S., … & Bandyopadhyay, U. (2010). Gallic acid prevents nonsteroidal anti-inflammatory drug-induced gastropathy in rat by blocking oxidative stress and apoptosis. Free Radical Biology and Medicine, 49(2), 258-267.
V. opulus showed gastroprotective activity in rats. From: Zayachkivska, O. S., Gzhegotsky, M. R., Terletska, O. I., Lutsyk, D. A., Yaschenko, A. M., & Dzhura, O. R. (2006). Influence of Viburnum opulus proanthocyanidins on stress-induced gastrointestinal mucosal damage. Journal of physiology and pharmacology, 57, 155.