IngredientsSlippery elm (Ulmus rubra) is a broad-leafed deciduous tree native to Eastern and Central United States and Canada, the inner bark of which is used orally to treat sore throat and gastrointestinal upset and topically for skin rash and irritation. Also known as red elm, it is called slippery because of the slippery texture of the inner bark when it is chewed or mixed with water. Additional common names include moose elm, Indian elm, and grey elm. The genus Ulmus is proto-European for "mountain elm," and the specific epithet rubra refers to the red color of the bark.
Its accepted botanical name is Ulmus rubra, with the synonym Ulmus fulva still encountered in older literature. Its plant family is Ulmaceae. The tree's range extends from eastern Canada through the central and eastern United States, flourishing in moist woodlands and along riverbanks. It was designated as a specific species in 1793 by Gotthilf Muhlenberg, a German-American clergyman and botanist from Pennsylvania. Slippery elm trees can grow to a height of 65 feet and may have a diameter as large as 20 inches.
Slippery elm resembles the American Elm (Ulmus americana) but is less stately and less susceptible to Dutch Elm disease. Only the inner bark — not the outer bark, leaves, or other plant parts — is used medicinally. The inner bark is collected in the spring.
Slippery elm is available as tablets and capsules, lozenges, finely powdered bark for making teas or extracts, and coarsely powdered bark for poultices. The inner bark of slippery elm, when stripped of the outer bark, can be used as a lozenge to treat sore throat, as a pill for gastrointestinal upset, and as a cream or ointment for skin rash and wound healing. The inner bark is collected in the spring, dried, and typically ground to a fine powder before use. A cold overnight infusion in water can be sipped as a mucilaginous beverage. Alternatively, the bark may be ground into a powder and dissolved in hot water for a tea, or prepared as a thick nourishing gruel to support healing.
Slippery elm preparations were used in Native American traditional medicine for gastrointestinal and urinary tract disorders and topically for skin diseases. The historical significance of slippery elm bark can be traced back to Native American tribes, who revered the tree for its versatility in addressing various health concerns. The Cherokee, Iroquois, and other indigenous communities utilized the bark for its soothing and healing properties.
The inner bark of Ulmus rubra was used widely to poultice eyes, sores, burns, and wounds. Chewed or taken as a decoction, the bark soothed stomach and bowels, served as a mild laxative, supported women during pregnancy, and treated heartburn, dysentery, chronic bowel complaints, sore throats, and coughs. It was also used to treat quinsies (peritonsillar abscess), catarrhs, colds, and consumption.
Slippery elm has been used medicinally by Native Americans for centuries, who would soak the bark and use it as natural bandages and wrap the bark around food to preserve it. Slippery elm also served as a source of nutrition during famine and for making porridge for children and the elderly.
One notable application was in the form of a poultice, where the powdered bark was mixed with water to create a thick paste. This poultice was applied externally to wounds, burns, and other skin irritations. A decoction of the bark was used as a laxative and to aid delivery in childbirth.
The dried inner bark of the slippery elm tree was a favorite medicinal substance of many Indigenous American tribes and was subsequently adopted by European colonists. Like marshmallow and mullein, slippery elm was used as a treatment for sore throat, coughs, dryness of the lungs, skin inflammation, wounds, and digestive tract irritation. It was also made into a porridge to be taken by weaned infants and during recovery from illness.
European settlers called the tree "Indian elm" and quickly adopted the herb. Its use was well established by the 1600s. Various heroes of the American Civil War are said to have credited slippery elm with their recovery from war wounds. George Washington and his troops are believed to have subsisted for several days on gruel made from slippery elm bark during the cold winter at Valley Forge, Pennsylvania.
Slippery elm was included in the United States Pharmacopeia from 1820 to 1960, based largely on its historical use in soothing skin and digestive irritations and as a cough suppressant.
Nineteenth-century doctors and herbalists recommended slippery elm tea in the management of lung diseases such as pneumonia, consumption (tuberculosis), and pleurisy. Midwives also used slippery elm as a birth aid because its lubricant properties were believed to ease labor.
Slippery elm was one of the original herbs included in the famous Essiac mixture, the herbal anti-cancer formula devised by the Canadian nurse Rene Caisse. Slippery elm is one of the components in Essiac, an herbal formula used as an alternative cancer treatment. No clinical evidence supports Essiac as a cancer treatment, and this use remains unsupported by rigorous research.
Slippery elm inner bark is predominantly composed of dietary fiber including celluloses, lignin, mucilage, and gums. The mucilage consists of long-chain polysaccharides which combine with water to form a viscous, semi-solid mass, and is regarded as the main active constituent. The polysaccharides are composed of D-galactose, L-rhamnose, and D-galacturonic acid and their methylated derivatives, and are highly branched. Other constituents include phytosterols, starch, minerals, and oleic and palmitic acids.
It contains a complex assortment of chemical and nutritional compounds including mucilage (hexoses, pentoses, methylpentoses), glucose, polyuronides, tannins, starches, fat, phytosterols, and various nutrients (calcium, iron, zinc, magnesium, potassium).
The active ingredients appear to be mucilages, but the inner bark is also rich in tannins and resins which are astringents and may account for some of its effects.
The principal recognized mechanisms of slippery elm are physical and demulcent rather than pharmacological in the conventional drug sense:
The overall body of clinical evidence for slippery elm is limited. Few studies on slippery elm have been reported. Modern scientific evidence for slippery elm's efficacy is limited and mostly based on small pilot studies, case reports, or extrapolation from its general demulcent properties. The following subsections summarize the available evidence by indication.
The FDA OTC monograph recognizes slippery elm inner bark as a safe demulcent for sore-throat irritation. That regulatory recognition is the strongest evidence anchor the ingredient carries, and it is worth noting because very few herbal ingredients hold a dedicated OTC monograph status.
The most directly relevant clinical trial involved a multi-herb formulation containing slippery elm. A multi-centre, randomised, double-blind, placebo-controlled study was carried out to investigate a demulcent herbal tea formulation ("Throat Coat®," containing 8.5% U. rubra powder) for the symptomatic treatment of acute pharyngitis. Patients were given either Throat Coat (n = 30) or placebo (n = 30). Throat Coat was found to be significantly superior to placebo in providing rapid, temporary relief from sore throat pain in patients with pharyngitis (Brinckmann et al. 2003). An important limitation, however, is that Throat Coat contains multiple herbs; it is therefore not possible to attribute the benefit solely to slippery elm.
The demulcent effect on the oropharynx has the strongest direct human-trial evidence in the slippery-elm-adjacent literature. A controlled lozenge onset-of-action study demonstrated that the demulcent base itself produced measurable, short-duration sore-throat relief. In a separate RCT, the demulcent placebo lozenge arm produced meaningful sore-throat relief, reinforcing that coating alone is an active mechanism. These are demulcent-class trials, not slippery-elm-specific trials.
Commercial lozenges containing slippery elm are preferred to the native herb when used for sore throat. The lozenges prolong the pain-relieving effect.
The principal human clinical study in IBS was a pilot trial by Hawrelak and Myers (2010), published in the Journal of Alternative and Complementary Medicine. The study objective was to assess the effects and tolerability of two novel natural medicine formulations in improving bowel habit and abdominal symptoms in patients with IBS. The DA-IBS formula was designed to treat diarrhea-predominant and alternating-bowel-habit IBS, and the C-IBS formula was designed to treat constipation-predominant IBS. This was a two-arm, open-label, uncontrolled pilot study, with subjects recruited from the greater Lismore area (NSW, Australia). The study included 31 patients who fulfilled the Rome II criteria for IBS; 21 were classified as having diarrhea-predominant or alternating bowel habit IBS, and 10 with constipation-predominant IBS.
The DA-IBS formula consisted of a mixture of dried, powdered bilberry fruit, slippery elm bark, agrimony aerial parts, and cinnamon quills. The C-IBS formula consisted of a mixture of dried powdered slippery elm bark, lactulose, oat bran, and licorice root. Ingestion of the DA-IBS formula was associated with a small but significant increase in bowel movement frequency (p = 0.027). Subjects in the DA-IBS group also experienced reductions in straining (p = 0.004), abdominal pain (p = 0.006), bloating (p < 0.0001), flatulence (p = 0.0001), and global IBS symptoms (p = 0.002) during the treatment phase. Subjects in the C-IBS group experienced a 20% increase in bowel movement frequency (p = 0.016) and significant reductions in straining (p < 0.0001), abdominal pain (p = 0.032), bloating (p = 0.034), and global IBS symptom severity (p = 0.0005), as well as improvements in stool consistency.
A critical limitation of this study is that the bark was part of a mixture of ingredients, and no study to date has supported these findings with an isolated slippery elm arm. The IBS evidence is preliminary, unreplicated, and almost entirely from multi-herb formulas.
The daily dose of slippery elm that was demonstrated as potentially beneficial for the reduction of abdominal pain, bloating, and flatulence in individuals suffering from IBS was 9 g per day (within the multi-herb C-IBS formula).
Slippery elm has been used traditionally to treat coughing, diarrhea, and gastrointestinal tract diseases by Native Americans. Recently, the bark of slippery elm was suggested to be effective for treating IBD patients owing to its antioxidant effects; however, further studies are needed to confirm its efficacy.
The primary laboratory evidence comes from an in vitro study by Langmead et al. (2002), published in Alimentary Pharmacology & Therapeutics. An in vitro study was carried out to investigate the antioxidant effects of herbal therapies used by patients with inflammatory bowel disease. Among the herbs tested were slippery elm, fenugreek, devil's claw, tormentil, and wei tong ning. Chemiluminescence was used to identify the effects of the herbs on oxygen radicals under mucosal biopsies taken from patients with active ulcerative colitis. It is unclear whether the herbs were applied in combination or individually. The results showed that oxygen radical release from biopsies was reduced after incubation. The study concluded that all six herbs have antioxidant effects.
In that study, slippery elm was found to elicit a similar response in patients with the inflammatory bowel disease ulcerative colitis when compared with 5-aminosalicylic acid. Researchers examined the anti-inflammatory effect of slippery elm on colonic cells biopsied from 45 patients with active ulcerative colitis, with findings revealing a nearly equal dose-dependent response in both slippery elm and 5-aminosalicylic acid. Further investigation is needed to assess the effects of slippery elm as a novel therapy in inflammatory bowel disease.
There is some interesting lab research, but no proven clinical benefit in IBD at this time. Scientific research on slippery elm's efficacy specifically for IBD is limited.
Its medicinal effects appear to be due to stimulation of mucous and saliva, which may alleviate sore or dry throat and coat irritated or ulcered esophageal or gastric mucosa. The mucosal-coating proof-of-concept for GERD is preclinical and comes from analog mucilages, not from human trials of slippery elm. Models with alginate, cashew gum, and lemon gum establish that mucilage-class polysaccharides can physically protect the esophageal epithelium from acid exposure, but none of those studies used slippery elm. Direct human trial data for slippery elm in GERD are absent.
Mucilage in slippery elm is responsible for its demulcent, emollient, and antitussive properties. The mucilage coats the throat, so it is unsurprising that slippery elm is present in many brands of throat lozenges. While slippery elm may help manage a cough or sore throat, there are not enough human studies to support this specifically.
The bark is traditionally used as an external treatment for burns, infected or inflamed wounds, and other ruptures and skin complaints. Additionally, the external application of slippery elm is indicated in other skin inflammations and irritations such as abrasions, minor burns, scalds, boils, and abscesses. Some slippery elm products are applied to irritated skin, but this use is also not well studied.
Slippery elm preparations were used in Native American traditional medicine for gastrointestinal and urinary tract disorders. Traditionally, it has been used to relieve inflammation of the urinary tract. No controlled human clinical trials specifically evaluating slippery elm for urinary tract indications have been identified.
Some in vitro studies have demonstrated antioxidant and anti-inflammatory effects, and small clinical trials have suggested that slippery elm may improve symptoms such as abdominal pain and diarrhea in people with irritable bowel syndrome (IBS). However, the evidence base as a whole is characterized by a very small number of human trials, most using multi-ingredient formulas, an absence of large-scale randomized controlled trials isolating slippery elm's specific effect, and a predominance of in vitro and traditional-use data. Slippery elm remains a popular ingredient in cough lozenges, but the scientific research supporting these uses is limited. Some small-scale studies suggest its effectiveness for cough relief, but overall, there is a lack of substantial evidence backing its efficacy for other claims.
Slippery elm is associated with the following body systems based on traditional use and the available scientific literature:
Slippery elm is available as tablets and capsules, lozenges, finely powdered bark for making teas or extracts, and coarsely powdered bark for poultices.
Specific dosages reported in sources include:
Researchers have not established what amount of slippery elm makes up a safe dose, and there is no research on how much slippery elm one should take or how often. Dosage guidance in commercial products varies considerably.
Slippery elm preparations are generally recognized as safe and there is no evidence that they can cause elevations in liver-related enzymes or clinically apparent liver injury. The FDA classifies slippery elm as "generally recognized as safe" (GRAS). While not approved as therapy for any disease or condition, over-the-counter preparations are sold as demulcents and for gastrointestinal upset.
The mucilage present in slippery elm may reduce absorption of medicines if taken concomitantly, and it has been suggested that other medicines should be taken 1 hour prior to, or several hours after, slippery elm preparations. Slippery elm should be taken 2 hours before or after other medications. It coats the lining of the GI tract and may interfere with the absorption of other medications. The interactions between slippery elm and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with slippery elm is incomplete.
Folklore says that slippery elm bark can cause a miscarriage when it is inserted into the cervix of a pregnant woman. It is not recommended during pregnancy and lactation, in children and adolescents under 18 years of age, or in patients with liver disease, gallstones, and other biliary disorders, due to lack of safety data.
Slippery elm can cause allergic reactions in sensitive people. Slippery elm ointment on the skin can sometimes cause a rash. In some people, slippery elm can cause allergic reactions and skin irritation when applied to the skin.
Side effects are usually mild and relate to texture and serving size: fullness, bloating, or nausea. Some experience nausea or texture aversion to the "slimy" consistency when mixed with water.
Slippery elm is currently included on the United Plant Savers "At-Risk" List due to concerns over the continued industry dependence on wild-harvested material to fill market demand. It is under pressure due to overharvesting and to Dutch Elm disease, which has reduced populations of elm species. Since the inner bark of slippery elm is used medicinally, harvesting the tree can kill it, and slippery elm should not be used from wild-harvested sources. The slippery elm is a rare or threatened species in some parts of the United States, particularly in the northeastern US where Dutch Elm disease has devastated elm forests. United Plant Savers recommends that plants defined as at-risk be used in cultivated forms whenever possible. Wildharvesting should be very limited, carefully monitored, and aligned with federal, state, and local rules.
Health conditions that Slippery elm bark may help support.
Clinical data from both the Hawrelak & Myers IBS pilot study and the Australian multi-ingredient gut supplement study demonstrate significant reductions in abdominal pain and bloating with slippery elm-containing formulas. Attribution to slippery elm alone remains uncertain given multi-ingredient compositions, but the evidence is human clinical in nature.
In vitro and ex vivo studies have confirmed measurable antioxidant and free radical-scavenging activity in slippery elm bark extracts, including peroxynitrite scavenging and superoxide scavenging in IBD patient tissue comparable to 5-ASA. The bark's polyphenols, tannins, and flavonoids are the active antioxidant constituents.
Ex vivo laboratory studies in IBD patient tissue demonstrated anti-inflammatory and antioxidant effects of slippery elm extract, with superoxide scavenging activity comparable to 5-ASA. The inner bark tannins and polyphenols also contribute documented anti-inflammatory activity. These are in vitro findings; no controlled human trials of slippery elm for systemic chronic inflammation have been conducted.
Slippery elm bark polysaccharides and arabinogalactan-type fibers are documented as having prebiotic potential, feeding Lactobacillus and Bifidobacterium species. A 2018 review in the Journal of Alternative and Complementary Medicine (Peterson et al.) specifically evaluated slippery elm among herbs with prebiotic potential for digestive health. A 2020 clinical study also documented improved microbial profiles in participants taking a slippery elm-containing formula.
The strongest clinical evidence for slippery elm is in IBS. A 2010 published pilot study (Hawrelak & Myers) using two slippery elm-containing formulas in 31 IBS patients found significant improvements in bowel movement frequency, stool consistency, abdominal pain, bloating, and global symptom severity—particularly in constipation-predominant IBS. MSKCC and Memorial Sloan Kettering both cite this as supporting evidence.
Laboratory studies have demonstrated antioxidant activity of slippery elm in tissue from IBD patients comparable to 5-aminosalicylic acid. A PMC review and the Saudi Journal of Gastroenterology confirm these antioxidant findings in IBD patient tissue. Human clinical trials are lacking, but the ex vivo tissue evidence constitutes preliminary scientific evidence.
A multi-ingredient clinical study including slippery elm demonstrated significant reduction of intestinal permeability (measured by lactulose-to-mannitol ratios) in Australian adults with digestive disorders over three months. In vitro and in vivo studies suggest slippery elm mucilage enhances epithelial repair. However, slippery elm has not been tested in isolation for leaky gut.
Slippery elm is one of the most well-established uses: the FDA recognizes it as a safe and effective oral demulcent for sore throat. Memorial Sloan Kettering notes it may help relieve minor cough or sore throat. Mucilage coating of pharyngeal mucosa is the accepted mechanism, and the bark is widely incorporated into throat lozenges on this basis.
Slippery elm bark has been used in traditional Native American and folk herbal medicine as a topical poultice for boils and abscesses. The mucilage is thought to soften tissue and draw out infection when applied as a paste. No controlled human clinical studies exist for this specific indication.
Slippery elm has a long traditional history of use for heartburn and indigestion, supported by its mucilage mechanism: when mixed with water the gel coats the esophageal and gastric mucosa. A multi-ingredient Australian clinical study including slippery elm reported reductions in heartburn and reflux symptoms, but slippery elm was not isolated as the active agent. Formal review of available research has found little standalone clinical evidence that it helps GERD.
Slippery elm bark's mucilaginous polysaccharides are used in traditional herbalism to protect and soothe inflamed anorectal tissue in anal fissures, reduce irritation, and support mucosal healing. It is cited in multiple herbal therapeutic databases as a specific supportive ingredient for anal fissure and fistula. Traditional use is established in North American botanical and Eclectic medicine.
Slippery elm has a documented traditional role in soothing the respiratory mucosa, particularly for dry, unproductive coughs and throat irritation. Its mucilage is thought to coat and soothe inflamed bronchial and pharyngeal membranes. Clinical evidence is limited and mostly confined to sore throat lozenges; no bronchial-specific trials have been conducted.
Slippery elm bark is the primary medicinal part of Ulmus rubra, listed in the EBSCO Research Starters evidence database among proposed bronchitis treatments. It is listed in the US Pharmacopeia as an emollient and demulcent for irritated mucous membranes. Its mucilaginous properties soothe bronchial mucous membranes and reduce cough irritation.
Slippery elm bark has been applied as a topical poultice for burns and scalds in Native American and early American folk traditions. The mucilage creates a moist, cooling, protective layer over damaged skin. No human clinical trials specifically for burns have been conducted.
Slippery elm bark (Ulmus rubra) is used in North American traditional medicine for sore throat, cough, and pharyngeal irritation associated with cold and flu. The FDA recognizes slippery elm bark as a safe and effective OTC oral demulcent for sore throat. EBSCO lists slippery elm as a proposed natural treatment for cold and flu. It has been used by Native American tribes for respiratory ailments for centuries.
Slippery elm bark has a documented traditional use for colic, cited in multiple herbal references and historically used as a soothing porridge for weaned infants. No controlled clinical trials have evaluated this application. The soothing demulcent effect on gastrointestinal mucosa provides the rationale.
Slippery elm bark has a well-documented Native American traditional use for gastrointestinal inflammatory conditions including colitis. Its mucilage forms a soothing coating on inflamed colonic mucosa. Preliminary research supports antioxidant effects relevant to IBD, but formal RCT data are absent.
Slippery elm bark (Ulmus rubra) produces a thick mucilage that coats and soothes the intestinal and colonic lining, traditionally used in North American herbal medicine as a demulcent and gentle bowel normalizer. It is a standard ingredient in commercial colon-cleanse formulas, acting as a mucosal protectant rather than a stimulant laxative. Clinical evidence is primarily traditional and mechanistic.
Slippery elm bark (inner bark of Ulmus rubra) contains demulcent mucilage that acts as a bulk-forming and lubricating laxative. A 2021 review confirmed it stimulates intestinal mucin production. Included in combination herbal formulas showing IBS-C improvement; isolated placebo-controlled human RCTs are not available.
Slippery elm is listed in herbalist and integrative medicine references as a traditional supportive remedy for Crohn's disease, primarily due to its demulcent properties and potential to soothe inflamed intestinal mucosa. No Crohn's-specific clinical trials have been conducted.
Slippery elm has been used traditionally by Native Americans for diarrhea, and is cited across herbal references for this indication. The soluble fiber mucilage can absorb excess luminal water and the tannins provide astringent activity. Clinical evidence for slippery elm alone treating diarrhea is lacking; MSKCC states evidence is absent for this specific claim.
Slippery elm is traditionally listed in herbal and integrative references for diverticulitis. RxList and Herbal Reality both cite diverticulitis among its traditional indications. The mucilage is proposed to soothe inflamed diverticula and support bowel regularity. No clinical trials specifically for diverticulitis have been identified.
Slippery elm bark is traditionally used for gastritis and stomach irritation, with its mucilage proposed to coat and protect the gastric mucosa from acid and inflammatory insult. It is listed across multiple herbal references for this indication. Preliminary clinical data from multi-ingredient supplement studies are suggestive but not isolating.
Slippery elm bark is listed in multiple traditional medicine references for hemorrhoid relief, both orally and topically. The mucilage softens stool to reduce straining, and topical preparations may soothe inflamed anorectal tissue. No clinical trials specific to hemorrhoids have been conducted.
Slippery elm bark (Ulmus rubra) is the dried inner bark used as a demulcent for respiratory mucous membrane soothing. It is recognized by the FDA as a safe OTC demulcent and has traditional use in treating cough and airway irritation. Its mucilage content provides protective coating to inflamed airway tissue.
Slippery elm bark (inner bark of Ulmus rubra) contains polysaccharide mucilage that coats and soothes the throat and respiratory tract, traditionally used by Native Americans for cough and respiratory conditions. Western herbalism classifies it as a demulcent expectorant for sticky, irritating mucus and unproductive cough. Evidence is primarily traditional with recognition in naturopathic and herbal pharmacopeias.
Slippery elm has been traditionally used for nausea and stomach upset. An Australian multi-ingredient clinical study including slippery elm reported reduced nausea among participants with digestive disorders. However, slippery elm has not been studied in isolation for nausea, and attribution cannot be confirmed.
Slippery elm bark is specifically the pharmaceutical/herbal preparation form of Slippery Elm (Ulmus rubra inner bark) traditionally used for tonsillitis and sore throat. Its mucilage coats and soothes inflamed tonsillar mucosa. Multiple authoritative herbal references specifically recommend the bark preparation for tonsillitis symptom management.
Slippery elm has a long traditional use for gastric and duodenal ulcers. RxList and other references list stomach ulcer prevention among its traditional indications. The mucilage is proposed to form a protective barrier over ulcerated mucosa. No controlled clinical trials for gastric ulcer treatment have been published.
Slippery elm bark (Ulmus rubra inner bark) is an FDA-recognized safe and effective OTC throat demulcent. Its mucilage physically coats irritated pharyngeal mucosae to soothe sore throat and cough associated with upper respiratory infections. Used for centuries in North American Indigenous medicine for respiratory conditions.
Slippery elm has a well-documented traditional use for urinary tract inflammation and irritation in Native American medicine. The NIH LiverTox monograph explicitly states it was used for urinary tract disorders. No controlled human trials for urinary indications exist.
Slippery elm bark has traditional documented use for UTI and urinary tract inflammation by Native Americans and is listed across multiple herbal references for cystitis. No controlled clinical trials for UTI exist. The soothing demulcent mechanism is the rationale for this traditional use.
Slippery elm has a deeply documented traditional role in wound healing, from Native American use and Civil War accounts to modern traditional herbal references. The mucilage creates a moist, protective environment promoting tissue regeneration. No controlled human trials for wound healing specifically have been published.
Body systems that Slippery elm bark may help support.
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