Slippery elm
Summary
Slippery elm is the inner bark of a North American elm, rich in gel-forming mucilage. It is traditionally used for sore throat and digestive upset, but no controlled trial has tested it on its own; the only human data come from multi-herb blends (grade D). LiverTox finds no evidence of liver injury, and it is generally regarded as safe.
Key facts
- Inner bark of Ulmus rubra, a deciduous tree of eastern and central North America[1]
- Sore throat and stomach upset by mouth; skin irritation on the skin[1]
- No evidence of liver-enzyme rises or clinically apparent liver injury[1]
- A 2019 review found a large gap between anecdotal and tested evidence for slippery elm and similar remedies[5]
- 3 graded human outcomes on this page
- October 13, 2026
How it works
ProposedThe inner bark contains mucilage, a gel-forming mix of sugars identified in early chemistry work. It is thought to coat and soothe the throat and gut lining. This has not been confirmed in controlled human studies.[7][1]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Digestive symptoms with a multi-ingredient gut formula | Improved | Grade D | Open-label trial · n = 43 · 2020 Adults with digestive disorders (Australia) Form: Formula with curcumin, aloe vera, slippery elm, guar gum, pectin, peppermint oil and glutamine · Dose: 5 g/day, then 10 g/day · Duration: 16-week pre-post study After a control phase, upper and lower digestive symptom scores improved by 60–80% over the study. There was no placebo group. | 32151878 (opens PubMed)Source [3] |
| Digestive symptoms and body composition (detox blend with slippery elm) | No effect | Grade D | RCT · n = 22 · 2019 Healthy young women Form: Proprietary blend of papaya leaf, cascara, slippery elm bark, peppermint, raspberry leaf, fenugreek, ginger and senna · Dose: 1,350 mg/serving blend, daily · Duration: 4 weeks No benefit or harm versus placebo for digestive symptoms, body composition, waist size or blood markers. | 29958034 (opens PubMed)Source [4] |
| IBS symptoms with a slippery elm-containing formula (constipation type) | Improved | Grade D | Open-label trial · n = 10 · 2010 Adults with constipation-predominant IBS (Australia) Form: Formula of slippery elm bark, lactulose, oat bran and licorice root · Dose: Dose not stated in the abstract · Duration: Treatment phase of an uncontrolled pilot In the 10-person constipation arm, bowel movements rose 20% and straining, pain, bloating and global IBS severity fell during treatment (P<0.05 for each). The formula also contained lactulose, a laxative, and there was no control group. | 20954962 (opens PubMed)Source [2] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Powdered inner bark (mixed with water) | Varies[1][7] | No human absorption study; the mucilage acts in the mouth, throat and gut rather than being absorbed.[1][7] | LiverTox finds no evidence that slippery elm raises liver enzymes or causes liver injury.[1] | Traditional use for sore throat and stomach upset; no single-ingredient trial |
| Lozenges | Varies[1] | Acts locally in the throat.[1] | No adverse effects were reported in the PDR monograph summarized by LiverTox.[1] | Sore throat (traditional use) |
| Multi-herb blends (IBS, gut and Essiac formulas) | Varies[2][3][4][6] | Not studied for slippery elm itself.[2][3][4][6] | The pilot formulas were well tolerated; the detox blend showed no harm in blood markers.[2][4] | IBS, digestive symptoms, detox and Essiac products |
Studied doses
Doses studied in human trials ranged from a 1,350 mg/day blend (slippery elm amount undisclosed) to 5–10 g/day of a multi-ingredient gut formula, for 4 to 16 weeks. No trial has tested slippery elm alone.[4][3]
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Oral medicines taken at the same timeReviewSlippery elm's mucilage may slow or reduce absorption of other oral medicines; a professional monograph suggests separating doses by one to several hours. No human interaction study exists.[8]
Who should be careful
- Pregnancy and breastfeeding
- A professional monograph advises avoiding slippery elm in pregnancy because abortion-inducing effects have been described (linked to vaginal use of bark pieces); no trial enrolled pregnant or breastfeeding women.[8][2][3][4]
- People on other oral medicines
- The gel-forming mucilage may slow or reduce absorption of medicines swallowed at the same time; separating doses by one to several hours is suggested.[8]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
How to read the label
Frequently asked questions
Does slippery elm help IBS?
It has not been tested alone. One uncontrolled pilot of a slippery elm-lactulose-oat bran-licorice formula improved constipation-type IBS symptoms in 10 people, but the effect cannot be credited to slippery elm.[2]
Does slippery elm help acid reflux or sore throat?
These are traditional uses. A 2019 review of popular esophageal remedies found the evidence is largely anecdotal.[1][5]
Is slippery elm safe for the liver?
LiverTox finds no evidence that slippery elm raises liver enzymes or causes liver injury, and it is generally regarded as safe.[1]
Is slippery elm in Essiac tea?
Yes. Essiac blends include slippery elm inner bark with burdock, Indian rhubarb and sheep sorrel. A study of 510 women with breast cancer found no quality-of-life benefit from Essiac.[6]
How does slippery elm work?
Its inner bark is rich in mucilage, a gel-forming carbohydrate thought to coat the throat and gut. That idea has not been tested in controlled human trials.[7][1]
Does slippery elm interact with medicines?
No interaction has been documented in people, but its mucilage may slow absorption of other oral medicines, so a professional monograph suggests spacing doses one to several hours apart.[8]
Sources
- [1]Slippery Elm.. LiverTox (NIDDK), 2012. database
- [2]Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study.. J Altern Complement Med, 2010. open-label
- [3]Herbal formula improves upper and lower gastrointestinal symptoms and gut health in Australian adults with digestive disorders.. Nutr Res, 2020. open-label
- [4]A Purported Detoxification Supplement Does Not Improve Body Composition, Waist Circumference, Blood Markers, or Gastrointestinal Symptoms in Healthy Adult Females.. J Diet Suppl, 2019. RCT
- [5]Popular Remedies for Esophageal Symptoms: a Critical Appraisal.. Curr Gastroenterol Rep, 2019. review
- [6]Trial of Essiac to ascertain its effect in women with breast cancer (TEA-BC).. J Altern Complement Med, 2006. observational
- [7]Chemical constitution of slippery elm mucilage; isolation of 3-methyl d-galactose from the hydrolysis products.. Nature, 1950. animal-study
- [8]Slippery Elm (natural product monograph for professionals; last updated Aug 24, 2026). Drugs.com (Wolters Kluwer), 2026. database
What changed
- Independent adversarial review: page had no interaction entry. Added the mucilage absorption interaction (separate doses), the pregnancy caution (abortifacient reports) and an FAQ, sourced to the Drugs.com professional monograph.
- Adversarial review pass: every evidence row's numbers re-checked against its abstract (Europe PMC for abstracts PubMed truncates, PMC full text where open), grades checked against the grading rubric, and safety and overclaim wording re-read. Fixes: IBS row now states the 10-person constipation arm, the lactulose in the formula and the lack of a control group; gut-formula row no longer implies a comparison with the control phase.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year taken from the record) and abstracts read for the cited rows.
- Strict second-pass self review (no separate reviewer agent was available for this batch): every PMID re-fetched via esummary and every evidence row, dose and safety line re-read against its abstract or fact sheet. No NIH ODS or NCCIH fact sheet exists for slippery elm; LiverTox (first posted 2012, updated 2024) is the federal reference used. Every human study found tested slippery elm inside a blend, so all rows are marked as not form-specific. Retraction and erratum flags checked on all PMIDs: none.