Herbal Monograph
Slippery elm
Ulmus rubra Muhl.
Ulmaceae
Nature's bandage for the gut — the premier mucilaginous demulcent of North Am...
Overview
Plant Description
Ulmus rubra is a medium-sized deciduous tree growing 12–20 m (40–65 ft) tall, occasionally reaching 25 m, with a broad, open, flat-topped crown and spreading branches. The trunk diameter reaches 30–60 cm (12–24 in) at maturity. Bark is dark reddish-brown to grey-brown on mature trunks, deeply furrowed with flat-topped ridges; the inner bark is conspicuously mucilaginous when chewed or moistened, exuding a thick, slippery, gel-like substance that gives the tree its common name. Twigs are coarse, grey-brown, pubescent, with prominent dark brown to nearly black buds densely covered in rusty-orange hairs. Leaves are alternate, obovate to oblong, 10–20 cm long, doubly serrate, with a very rough, sandpaper-like upper surface (more so than any other North American elm) and softly pubescent beneath, strongly asymmetrical at the base. Flowers are small, apetalous, reddish-green, in dense clusters appearing before the leaves in early spring (March–April). Fruit is a single-seeded samara, 1.5–2 cm across, orbicular, with a shallow notch at the apex, the seed centered within the wing, the surface smooth (not pubescent like leaf undersides).
Habitat
Native to mesic deciduous forests, bottomland woods, floodplains, stream banks, lower slopes, ravines, and limestone bluffs. Grows in moist, rich, well-drained soils, often in association with sugar maple, basswood, white ash, beech, and other hardwoods. Tolerates partial shade, particularly as a juvenile understory tree. Prefers neutral to slightly alkaline soils (pH 6.5–8.0). Found from near sea level to approximately 600 m elevation.
Distribution
Native to eastern North America, ranging from southern Quebec and Ontario westward to North Dakota and eastern Nebraska, south through the eastern United States to northwestern Florida and eastern Texas. Most common in the Ohio and Mississippi river valleys and the central hardwood forest region. Range has contracted in many areas due to Dutch elm disease.
Parts Used
Inner bark (Ulmi rubrae cortex)
Preferred: Powdered bark (mixed with water to form gruel or paste), lozenges, decoction, or cold infusion
The inner bark (phloem/bast layer) is the official medicinal part, containing approximately 50% mucilage by dry weight. It is the source of slippery elm's distinctive demulcent properties. The FDA recognizes slippery elm bark as an OTC Category I demulcent (21 CFR 310.545). The AHP monograph and BHP specify the dried inner bark. The outer bark is discarded as it does not contain significant mucilage.
Key Constituents
Mucilage polysaccharides
The mucilage is the primary active constituent responsible for virtually all of slippery elm's therapeutic actions. When mixed with water, it forms a viscous, demulcent gel that coats, soothes, and physically protects irritated or inflamed mucous membranes. The high mucilage content (~50%) makes slippery elm one of the most concentrated mucilaginous herbs in the Western materia medica. The mucilage also provides significant nutritive value as a complex carbohydrate.
Tannins
The tannin fraction provides mild astringent and tissue-toning properties, creating a balanced action — the mucilage soothes while tannins gently tighten inflamed tissues. This dual action makes slippery elm particularly effective for GI inflammation where both soothing and tissue repair are needed.
Phytosterols
Phytosterols contribute anti-inflammatory activity, particularly relevant to the traditional use for gastrointestinal inflammation. Their clinical contribution at the concentrations present in bark preparations is modest but supportive.
Minerals and other compounds
The starch and mineral content underpin the traditional use of slippery elm bark gruel as a nutritive food for convalescents, the elderly, and those with debilitated digestion — one of the few herbal medicines that is simultaneously a food and a medicine.
Herbal Actions
Soothes and protects irritated mucous membranes
Slippery elm is among the most potent demulcent herbs in Western herbal medicine, owing to its extraordinarily high mucilage content (~50% of dry inner bark). The mucilage forms a thick, bioadhesive gel that coats, soothes, and physically protects irritated or inflamed mucous membranes throughout the gastrointestinal tract, from the oropharynx to the colon. FDA approved as an OTC demulcent. Often described as 'nature's bandage' for the gut lining.
[1, 2, 4, 7]Promotes wound healing
The mucilage-rich bark has a long history of use as a wound-healing agent. Applied as a poultice, it creates a moist, protective environment over wounds, burns, boils, and ulcers that promotes tissue repair and prevents desiccation. The combination of soothing mucilage and mildly astringent tannins supports wound granulation and epithelialization.
[2, 7, 9]Tightens and tones tissue, reduces secretions
The tannin fraction (3–6%) provides a mild astringent action that tones relaxed or inflamed mucous membranes. This creates a unique dual action with the dominant mucilage — simultaneously soothing and toning tissues. Less astringent than dedicated astringent herbs but sufficient to complement the demulcent action.
[2, 10]Reduces inflammation
Anti-inflammatory activity is both physical (mucosal coating prevents irritant contact with inflamed tissue) and pharmacological (phytosterols, particularly beta-sitosterol, inhibit inflammatory mediators). The net effect is significant reduction of GI mucosal inflammation.
[7, 10]Prevents or slows oxidative damage to cells
Bark extracts demonstrate moderate antioxidant activity in vitro, attributed to the tannin and phenolic fractions. Langmead et al. (2002) demonstrated antioxidant activity of slippery elm in the context of inflammatory bowel disease research.
[5]Promotes the discharge of mucus from the respiratory tract
Acts as a soothing (demulcent) expectorant — the mucilage coats irritated bronchial membranes, reduces cough reflex sensitivity, and facilitates expectoration. Particularly effective for dry, non-productive coughs and sore throats. Traditionally classified as a 'reflex demulcent' — soothing the GI mucosa triggers a vagal reflex that increases bronchial secretion.
[2, 7]Therapeutic Indications
Digestive System
Gastritis and gastric ulceration
One of the most important traditional uses. The mucilage physically coats the gastric lining, forming a protective barrier between stomach acid and inflamed epithelium. AHP monograph supports this use. Bark gruel has been a staple remedy for gastric inflammation in North American herbal medicine for centuries. Often combined with marshmallow root and licorice.
[1, 2, 7]Gastro-esophageal reflux disease (GERD)
The viscous mucilage coats the esophageal and gastric mucosa, forming a raft-like protective layer conceptually similar to sodium alginate preparations. Traditionally used for heartburn, acid regurgitation, and esophageal irritation. The physical coating action provides rapid symptomatic relief.
[7, 10]Inflammatory bowel disease (IBD: Crohn's disease, ulcerative colitis)
Langmead et al. (2002) found slippery elm bark demonstrated antioxidant activity relevant to IBD in vitro. A pilot study of a herbal formula containing slippery elm showed symptom improvement in active Crohn's disease patients, though the multi-herb design prevents attribution to slippery elm alone. Traditional use for intestinal inflammation is well-documented.
[5, 10]Irritable bowel syndrome (IBS)
Traditional use for soothing intestinal irritation and calming bowel inflammation. The mucilage coats the intestinal epithelium, reducing irritant contact and potentially modulating visceral hypersensitivity. Hawrelak and Myers (2010) included slippery elm in a naturopathic protocol for IBS showing improvement in both constipation and diarrhea subtypes.
[6, 7]Diarrhea and dysentery
The combination of soothing mucilage and mildly astringent tannins makes slippery elm well-suited for diarrhea — the mucilage protects inflamed intestinal mucosa while tannins provide gentle tissue toning. Traditional use by both Native Americans and Eclectic physicians for acute and chronic diarrhea.
[2, 8, 9]Convalescent nutrition and debilitated digestion
Slippery elm bark gruel has been used for centuries as an easily digestible, nutritive food for convalescents, infants, the elderly, and those with severely irritated or ulcerated GI tracts who cannot tolerate other foods. The starch and mucilage provide gentle nourishment without irritating the gut.
[7, 8, 9]Respiratory System
Dry, irritative cough
Acts as a soothing demulcent expectorant — coats irritated bronchial membranes, reduces cough reflex sensitivity, and facilitates expectoration of dry, non-productive coughs. Traditionally combined with licorice, marshmallow, and wild cherry bark for persistent dry cough.
[2, 7]Bronchitis (dry, non-productive type)
Traditional demulcent expectorant for dry bronchitis with scanty, difficult expectoration. Not indicated for productive, wet coughs with copious sputum. The 'reflex demulcent' mechanism — soothing the GI tract triggering vagal-mediated bronchial secretion — is the proposed mechanism.
[2, 7]Urinary System
Urinary tract irritation and mild cystitis
BHP lists slippery elm as a urinary demulcent. Traditional use for cystitis, urethritis, and dysuria. The mucilage is thought to provide some soothing action on urinary mucosa, though the mechanism is less direct than GI application. Often combined with marshmallow root, corn silk, and bearberry.
[2, 7]Skin / Integumentary
Minor wounds, burns, and abrasions
Major traditional use as a poultice ('bark plaster'). The mucilaginous bark creates a moist, protective wound dressing that promotes healing, prevents desiccation, and soothes pain. Native American peoples used slippery elm bark poultices extensively for wounds, burns, boils, and skin ulcers. The Eclectics adopted and expanded this practice.
[2, 8, 9]Energetics
Temperature
cool
Moisture
moist
Taste
Tissue States
hot/excitation, dry/atrophy
Slippery elm is a quintessentially cool, moist remedy — the archetype of the nutritive demulcent. Its sweet, bland taste reflects the dominant mucilage and starch content. It directly counteracts hot, dry, irritated tissue states: inflamed mucous membranes that are red, raw, and deficient in their natural protective mucus coating. Ideal for conditions where tissue is depleted, atrophied, or overheated. The neutral-to-cool temperature means it can be used safely across a wide range of constitutions without aggravating cold conditions. The moistening quality is profound — few herbs match its capacity to restore hydration to desiccated tissues.
Traditional Uses
Native American Medicine
- Demulcent bark tea and gruel for sore throats, coughs, and intestinal inflammation
- Poultice of moistened inner bark for wounds, burns, boils, skin ulcers, and gunshot wounds
- Nutritive gruel for infants, the elderly, and convalescents
- Bark strips used as bandages and wound dressings — 'nature's bandage'
- Treatment of diarrhea and dysentery
- Facilitation of childbirth (bark tea as a parturient lubricant)
"Moerman (1998): Slippery elm was one of the most widely used medicinal trees among Native American peoples. The Menominee used the inner bark poultice for sores and wounds. The Iroquois used bark tea for sore throat and cough. The Meskwaki (Fox) used it as a poultice for boils and to ease childbirth. The Ojibwa prepared bark gruel as food for the sick. At least 28 distinct tribal groups documented medicinal use of U. rubra."
[9]
Eclectic and Physiomedical Medicine
- Demulcent for inflammation and ulceration of the stomach and bowels
- Nutritive gruel for exhaustion, convalescence, and diseases where the patient cannot retain food
- Poultice for inflamed surfaces, wounds, burns, boils, and abscesses
- Soothing expectorant for coughs and bronchial irritation
- Vaginal suppositories and rectal enemas for local inflammation
- Vehicle for administering other medicines (bark powder mixed with drug powders)
"Felter and Lloyd, King's American Dispensatory (1898): 'An efficient demulcent...in inflammatory conditions of the mucous membranes of the stomach, bowels, and urinary organs...The finely powdered bark makes an excellent gruel or food for infants, invalids, and convalescents; it is very nutritious and so bland as to be retained by the most delicate stomach.' 'As a poultice it is valuable for every case where a poultice is required.'"
[8]
American Folk Medicine
- Bark lozenges for sore throat and cough (a practice continuing to the present day)
- Bark tea as a household remedy for stomach upset, heartburn, and digestive complaints
- Bark gruel as convalescent food during illness and recovery
- Poultice for splinters, thorns, and drawing infections
"Slippery elm bark has been a staple of the North American domestic medicine chest since colonial times. Early settlers learned its uses from Native Americans and it became one of the most popular household remedies in 19th and early 20th century America. Commercially produced slippery elm throat lozenges have been sold continuously for well over a century."
Modern Research
Antioxidant activity and inflammatory bowel disease
In vitro study examined slippery elm bark alongside other herbal medicines for antioxidant activity relevant to inflammatory bowel disease.
Findings: Langmead et al. (2002) tested aqueous extracts of herbal medicines commonly used for IBD and found slippery elm bark demonstrated significant antioxidant activity, scavenging reactive oxygen species in a dose-dependent manner. The authors suggested this antioxidant activity could contribute to therapeutic benefit in IBD.
Limitations: In vitro study only. Clinical translation not established. Antioxidant activity in a test tube does not directly predict therapeutic efficacy in human IBD.
[5]
Naturopathic treatment of IBS
A pilot study evaluated a naturopathic protocol including slippery elm for irritable bowel syndrome.
Findings: Hawrelak and Myers (2010) conducted a pilot study of a naturopathic treatment protocol for IBS that included slippery elm bark alongside dietary modifications, probiotics, and other interventions. Both IBS-C (constipation) and IBS-D (diarrhea) subtypes showed improvement in symptom severity scores. Participants reported improved bowel habits and reduced abdominal pain.
Limitations: Multi-component intervention — improvements cannot be attributed solely to slippery elm. Small sample size. No placebo control. Open-label design.
[6]
Mucilage characterization and demulcent properties
Pharmacognostic studies characterizing the polysaccharide composition and physical properties of slippery elm bark mucilage.
Findings: The mucilage of U. rubra inner bark consists primarily of hexose and pentose sugar polymers including galactose, glucose, rhamnose, and galacturonic acid. On hydration, the mucilage swells to many times its dry volume, forming a highly viscous gel with significant bioadhesive properties. The mucilage content of the inner bark (~50% dry weight) is exceptionally high compared to other mucilaginous herbs, contributing to its reputation as one of the most potent botanical demulcents.
Limitations: Primarily descriptive pharmacognostic data. Formal clinical trials of slippery elm as a standalone agent remain limited.
Conservation status and sustainable sourcing
Research and position statements on the ecological status of Ulmus rubra and sustainable harvesting practices.
Findings: Dutch elm disease (caused by Ophiostoma novo-ulmi, vectored by bark beetles) has devastated North American elm populations since the mid-20th century, including U. rubra. Combined with increasing commercial demand for slippery elm bark, wild populations are under significant pressure. United Plant Savers lists U. rubra on its 'To Watch' list. Bark harvesting, if done improperly (girdling), kills the tree. Sustainable sourcing through branch harvesting, managed forestry, and cultivation is increasingly emphasized.
Limitations: Comprehensive population-level surveys of U. rubra are limited. Conservation status varies regionally.
[11]
Preparations & Dosage
Decoction
Strength: 1:8 (bark to water)
BARK DECOCTION: Place 2–4 g (approximately 1–2 teaspoons) of dried, powdered or coarsely cut slippery elm inner bark in 250 mL (1 cup) of cold water. Bring slowly to a gentle simmer, stirring frequently (the mucilage tends to thicken and settle). Simmer gently for 10–15 minutes. Remove from heat, cover, and steep for an additional 10 minutes. Strain if desired, though many practitioners consume the entire preparation including the bark material for maximum nutritive and demulcent benefit.
4–16 mL of a 1:8 decoction, or 0.5–2 g of powdered bark per dose
3 times daily, ideally between meals for GI indications
May be used continuously; no known time restrictions
Half adult dose for children 6–12 years; suitable for children as a nutritive gruel
The traditional 'bark tea.' The preparation becomes increasingly viscous as the mucilage hydrates. Best consumed warm. Prepare fresh daily as the carbohydrate-rich preparation supports microbial growth.
Capsule / Powder
Strength: Powdered whole inner bark
POWDERED BARK: Fill capsules with finely powdered slippery elm inner bark, or take the powder directly mixed into water, juice, or applesauce. Commercial capsules typically contain 300–500 mg of powdered bark per capsule.
400–800 mg powdered bark per dose, 3 times daily; or 1–2 g stirred into water as a gruel
3 times daily, preferably before meals
May be used continuously
200–400 mg for children 6–12 years
Convenient form retaining the full mucilage content. When the powder is mixed directly into warm water, it forms the traditional nutritive gruel. Capsule form is less effective as a topical demulcent for the esophagus and stomach since the mucilage is not released until the capsule dissolves.
Tincture
Strength: 1:5 in 25% ethanol
TINCTURE: Macerate powdered or finely cut slippery elm bark in low-alcohol menstruum (25–40% ethanol). Note: mucilage is water-soluble and poorly extracted by high-proof alcohol, making tincture a suboptimal preparation for slippery elm. A glycerite may be preferable.
5 mL of 1:5 tincture (25% ethanol) three times daily
3 times daily
4–8 weeks
Not the preferred form for children due to alcohol content and limited mucilage extraction
The least effective preparation for slippery elm because alcohol precipitates mucilage polysaccharides. Tinctures contain minimal mucilage and miss the herb's primary therapeutic action. Cold water preparations, powdered bark, or lozenges are strongly preferred.
Poultice
Strength: Thick paste consistency (approximately 1:2 powder to water)
POULTICE: Mix powdered slippery elm bark with warm water (or a warm infusion of other herbs such as calendula or chamomile) to form a thick, smooth paste. Spread directly onto the affected area in a layer approximately 0.5–1 cm thick. Cover with clean muslin or gauze. Replace every 2–4 hours or when dried.
Sufficient powdered bark to cover the affected area; apply 2–3 times daily
2–3 times daily; may be applied continuously for acute conditions
Until inflammation resolves or wound has healed (typically 3–10 days)
Same as adult, adjusted to area
The traditional 'slippery elm plaster.' One of the most highly regarded herbal poultices in North American herbalism. Creates an ideal moist wound environment. Felter and Lloyd stated it was 'valuable for every case where a poultice is required.'
Infusion (Tea)
Strength: 1:60 to 1:125 (bark to water)
COLD INFUSION: Place 2–4 g of powdered or finely cut slippery elm bark in 250 mL of cold or room-temperature water. Stir well and allow to stand for 30 minutes to 2 hours, stirring occasionally. The preparation will thicken as the mucilage hydrates. Consume as is, including the bark material, or strain through cheesecloth.
250 mL (one cup) 3 times daily
3 times daily between meals
May be used continuously
Half the adult volume for children 6–12
Cold infusion preserves the mucilage better than hot decoction (heat can partially degrade polysaccharides). Produces a thicker, more viscous preparation ideal for coating the upper GI tract. Can be gently warmed but should not be boiled.
[7]
Syrup
Strength: Variable; commercial lozenges typically contain 100–200 mg bark per lozenge
THROAT LOZENGES/SYRUP: For a syrup, prepare a strong cold infusion or decoction (1:5), strain, and add an equal volume of honey. Stir thoroughly. Refrigerate. Commercial lozenges contain powdered slippery elm bark compressed with sweetener and binder.
10–15 mL syrup 3–4 times daily for cough and sore throat; 1–2 lozenges as needed
Every 2–4 hours as needed for acute sore throat
As needed for acute conditions
5–10 mL syrup for children over 3 years; lozenges for children who can safely manage them
Slippery elm throat lozenges are one of the most widely available commercial herbal products, sold continuously for over a century. The lozenge form is particularly effective because it dissolves slowly in the mouth, providing prolonged mucosal contact time.
Safety & Interactions
Class 1
Can be safely consumed when used appropriately (AHPA Botanical Safety Handbook)
Contraindications
Allergic reactions to slippery elm are exceedingly rare but theoretically possible. No well-documented cases of anaphylaxis.
Drug Interactions
| Drug / Class | Severity | Mechanism |
|---|---|---|
| All oral medications (general class effect) (Any orally administered drug) | minor | The viscous mucilage may physically coat the GI mucosa and delay or reduce absorption of co-administered oral drugs. This is a non-specific physical interaction, identical to the interaction profile of marshmallow root. |
Pregnancy & Lactation
Pregnancy
likely safe
Lactation
likely safe
AHPA Class 1: 'Herbs that can be safely consumed when used appropriately.' No restriction on pregnancy or lactation use in the AHPA Botanical Safety Handbook. Long history of safe traditional use during pregnancy, including use as a nutritive food (bark gruel) by Native American and colonial-era women. No mutagenicity, teratogenicity, or reproductive toxicity reported. Note: Some historical texts mention the use of slippery elm bark as a mechanical cervical dilator (the bark swells on hydration), but this is a physical obstetric application unrelated to oral use. Oral consumption during pregnancy is considered safe.
Adverse Effects
References
Monograph Sources
- [1] Upton, R., Graff, A., Jolliffe, G., et al.. American Herbal Pharmacopoeia and Therapeutic Compendium: Slippery Elm Inner Bark — Ulmus rubra Muhl.. American Herbal Pharmacopoeia (2011) . ISBN: 978-1-929425-29-1
- [2] British Herbal Medicine Association. British Herbal Pharmacopoeia. BHMA (1996) . ISBN: 978-0-903032-09-5
- [3] Gardner, Z., McGuffin, M. (eds.). American Herbal Products Association's Botanical Safety Handbook, 2nd Edition. CRC Press (2013) . ISBN: 978-1-4665-1695-3
- [4] U.S. Food and Drug Administration. OTC Active Ingredients — Oral Demulcents (21 CFR 310.545). Federal Register / Code of Federal Regulations (1994)
Clinical Studies
- [5] Langmead, L., Dawson, C., Hawkins, C., Banna, N., Loo, S., Rampton, D.S.. Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study. Alimentary Pharmacology & Therapeutics (2002) ; 16(2) : 197–205 . DOI: 10.1046/j.1365-2036.2002.01157.x . PMID: 11860402
- [6] Hawrelak, J.A., Myers, S.P.. Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. Journal of Alternative and Complementary Medicine (2010) ; 16(10) : 1065–1071 . DOI: 10.1089/acm.2009.0090 . PMID: 20954962
Traditional Texts
- [7] Hoffmann, D.. Medical Herbalism: The Science and Practice of Herbal Medicine. Healing Arts Press (2003) . ISBN: 978-0-89281-749-8
- [8] Felter, H.W., Lloyd, J.U.. King's American Dispensatory, 18th Edition. Ohio Valley Company (1898)
- [9] Moerman, D.E.. Native American Ethnobotany. Timber Press (1998) . ISBN: 978-0-88192-453-4
Pharmacopeias & Reviews
- [10] Mills, S., Bone, K.. Principles and Practice of Phytotherapy: Modern Herbal Medicine, 2nd Edition. Churchill Livingstone / Elsevier (2013) . ISBN: 978-0-443-06992-5
- [11] United Plant Savers. Species At-Risk List and 'To Watch' List. United Plant Savers (2023)
Last updated: 2026-03-02 | Status: review
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