Slippery Elm
UlmaceaeUlmus rubra
Also known as: Red Elm, Indian Elm, Moose Elm
clinical_notes Clinical Summary
Slippery elm (Ulmus rubra) is a North American deciduous tree whose inner bark is prized for its remarkable mucilaginous properties.
When mixed with water, its polysaccharide-rich bark forms a viscous gel that coats and soothes irritated mucous membranes throughout the gastrointestinal and respiratory tracts, making it invaluable for conditions such as GERD, gastric ulcer, IBS, sore throat, and cough.
It is generally recognized as safe for most adults, with no documented hepatotoxicity, though medicinal doses should be avoided in pregnancy due to historical reports of abortifacient use, and it should be taken at least 2 hours apart from medications to prevent interference with drug absorption.
Pregnancy Safety
Insufficient data; historical use as abortifacient documented. Avoid medicinal doses in pregnancy. Food-level amounts are generally considered lower risk.
Lactation Safety
Insufficient safety data for lactation. Conservative avoidance recommended due to lack of studies.
warning Contraindications
- Pregnancy (high doses / as abortifacient) (avoid)Clinically Proven
- Drug absorption interference (caution)Theoretical
- Elm pollen allergy / contact sensitization (caution)Clinically Proven
vital_signs Clinical Profile
Primary Indications
- check_circle sore throat
- check_circle gastritis
- check_circle gastric ulcer
- check_circle GERD
- check_circle irritable bowel syndrome
- check_circle inflammatory bowel disease
- check_circle constipation
- check_circle diarrhea
- check_circle cough
- check_circle urinary tract inflammation
- check_circle wound healing
- check_circle skin irritation
Therapeutic Actions
System Affinities
- check_circle gastrointestinal
- check_circle respiratory
- check_circle urinary
- check_circle skin
labs Active Constituents
mucilaginous polysaccharides
cellulose
lignin
starch
phytosterols
tannins
oleic acid
palmitic acid
minerals
history_edu Traditional Use
No TCM data available for this herb yet.
Traditional Uses Across Healing Systems
While many herbs lack controlled clinical trials, centuries of traditional practice across cultures provide valuable insight into their therapeutic applications.
Inner bark used as a poultice for wounds, burns, boils, and skin ulcers; decoction drunk for sore throats, coughs, and gastrointestinal complaints; used as a lubricant to ease childbirth.
Used by numerous Native American tribes including the Cherokee, Iroquois, and Menominee.
Inner bark taken as a mucilaginous tea or powder to soothe the gastrointestinal tract in conditions including gastritis, peptic ulcer, IBS, and sore throat. Topically used as a poultice for wounds.
Formally recognized as a demulcent in the US Pharmacopoeia. Widely used by Eclectic physicians in the 19th century.
spa Parts Used
inner bark
- sore throat
- gastritis
- GERD
- peptic ulcer
- IBS
- cough
- urinary tract inflammation
- wound healing
The medicinal part; collected in spring. Dried and powdered for teas, capsules, or lozenges. Mixing the powder with water releases the mucilage. Only the inner bark (not outer bark) is used medicinally.
shield Safety
Contraindications — Evidence Basis
Pregnancy (high doses / as abortifacient)
Traditional use as an abortifacient has been documented historically. While food-level amounts are likely safe, medicinal doses should be avoided due to theoretical uterine-stimulating effects. Case reports of bladder calculi formation in pregnancy also noted.
Drug absorption interference
The mucilage may coat the gastrointestinal tract and delay or reduce absorption of oral medications. Take slippery elm at least 2 hours away from any medications.
Elm pollen allergy / contact sensitization
Oleoresins from Ulmus species can cause contact dermatitis; elm pollen is a known allergen. Individuals with known elm or Asteraceae sensitivities should use with caution topically.
Toxicity
No established toxic dose for inner bark. High doses may cause GI upset.
Large doses may cause loose stools or diarrhea.
Discontinue use; symptoms are self-limiting.
Adverse Effects
CYP Metabolism
No known CYP450 interactions. However, the mucilage physically coats the gut lining and may impair absorption of co-administered medications.
swap_horiz Interactions
Narrow Therapeutic Index Oral Drugs (Warfarin, Digoxin, Phenytoin, Levothyroxine, Cyclosporine)
Class: Multiple Drug Classes
Slippery elm bark mucilage (a complex polysaccharide) forms a thick gel-like layer coating the GI tract when hydrated. This physical barrier and increased viscosity reduces absorption rate and bioavailability of co-administered oral medications by impeding drug-mucosal contact and slowing gastric emptying. All orally administered drugs may be affected.
Separate slippery elm from all oral medications by at least 1-2 hours (take slippery elm at least 1 hour after medications, or per clinician guidance). Critical for narrow therapeutic index drugs: monitor INR, digoxin levels, thyroid function, and phenytoin/cyclosporine levels if slippery elm is started or stopped.
Levothyroxine (Synthroid, Euthyrox)
Class: Thyroid Hormone
Levothyroxine requires careful, consistent absorption on an empty stomach. Slippery elm mucilage coating the GI mucosa can form a physical barrier that reduces L-thyroxine absorption and bioavailability. Even small reductions in L-T4 absorption can lead to undertreated hypothyroidism with important clinical consequences.
Levothyroxine should be taken at least 30-60 minutes before breakfast on an empty stomach. If slippery elm is taken concurrently, separate by at least 4 hours. Monitor TSH levels when slippery elm is started or stopped in thyroid patients. Dose adjustment may be required.
Oral Antibiotics (Tetracyclines, Fluoroquinolones, Macrolides)
Class: Antibiotic
Slippery elm mucilage reduces the absorption of orally administered antibiotics by creating a physical gel barrier on GI mucosa and slowing transit. This may result in sub-therapeutic antibiotic concentrations, especially critical for infections requiring prompt therapeutic levels (e.g., community-acquired pneumonia, UTI).
Do not take slippery elm at the same time as oral antibiotics. Separate administration by at least 1-2 hours. Complete the antibiotic course as prescribed; sub-therapeutic levels may risk treatment failure and antimicrobial resistance development.
Oral Antidiabetic Agents (Metformin, Acarbose, Glipizide, Glyburide)
Class: Antidiabetic
Slippery elm mucilage slows gastric emptying and forms a physical barrier that may delay and reduce absorption of oral antidiabetic medications. This can lead to blunted postprandial glucose responses but also delayed drug onset of action and potentially unpredictable glycaemic control.
Take oral antidiabetics at least 1 hour before slippery elm preparations. Monitor blood glucose more closely when initiating slippery elm. The risk is low but important to acknowledge in patients with tight glycaemic control targets.
Topical Corticosteroids (Hydrocortisone, Betamethasone) used concurrently
Class: Corticosteroid
When slippery elm poultices are applied topically alongside topical corticosteroid creams, the occlusive, hydrating mucilage layer may increase skin hydration and potentially enhance percutaneous absorption of co-applied corticosteroids, leading to increased systemic exposure especially on compromised skin.
Apply topical corticosteroids and slippery elm poultices at different times or to different areas. If used together, monitor for signs of systemic corticosteroid effects (skin thinning, adrenal suppression) especially with prolonged use on large areas.
hub Combinations
Synergistic pairings can enhance therapeutic outcomes, while knowing suitable substitutes helps when specific herbs are unavailable or contraindicated.
Synergistic Combinations
3Chamomile
Traditional UseChamomile anti-spasmodic and anti-inflammatory actions complement slippery elm demulcent properties for IBS and functional dyspepsia.
Traditional pairing in Western herbal formulas for GI complaints.
Licorice Root
Moderate EvidenceLicorice provides additional anti-inflammatory and mucosal-healing properties (glycyrrhizin) complementing slippery elm mucilage for gastric and peptic ulcer support.
Traditional combination; licorice DGL well-studied for gastric mucosa protection.
Marshmallow Root
Traditional UseBoth are demulcent herbs with mucilaginous polysaccharides; combined use provides enhanced soothing of mucous membranes throughout GI and respiratory tracts.
Traditional clinical pairing; both used in Throat Coat formulation.
science Studies
Prebiotic Potential of Herbal Medicines Used in Digestive Health and Disease
In VitroThis in vitro fermentation study evaluated the prebiotic potential of slippery elm bark along with licorice and triphala by profiling human gut microbiota through 16S rDNA sequencing. Slippery elm supplementation drove profound changes in diverse microbial taxa, promoting growth of health-associated Bifidobacterium, Lactobacillus, and Bacteroides species while reducing the relative abundance of potential pathogens like Citrobacter freundii and Klebsiella pneumoniae. The herb also induced blooms of butyrate- and propionate-producing bacteria, suggesting beneficial effects on gut barrier function and inflammation. These findings support the hypothesis that slippery elm exerts its digestive benefits partly through prebiotic modulation of the gut microbiome. Clinical trials in humans are needed to validate these findings.
Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study
ObservationalThis pilot study evaluated two herbal formulas on irritable bowel syndrome symptoms, with one formula containing slippery elm bark designed to normalize bowel frequency and consistency. The diarrhea-predominant IBS formula (DA-IBS), which included slippery elm as a key ingredient, was associated with a small but statistically significant increase in bowel movement frequency and changes in stool consistency. Gut transit time and other bowel habit parameters also showed improvement in the treatment group. The study was limited by its open pilot design and multi-herb formulas, making isolation of slippery elm effects difficult. Nevertheless, results support further investigation of slippery elm-based preparations for IBS management.
medication Dosing
tea
1–3 teaspoons (2–6 g) inner bark powder in 240 mL water
2–3x/day
Stir powder into warm (not boiling) water to preserve mucilage; drink 30 minutes before meals for GI conditions.
capsule
400–500 mg standardized inner bark powder
3–4x/day
Take with a full glass of water. Take separately from other medications by at least 2 hours.
Disclaimer: This information is largely AI-generated and reviewed by human experts at Evara Health. It is intended for educational and clinical reference purposes only and should not replace professional medical advice.
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