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Western herbalism

Slippery elmUlmus rubra

A bark that turns to a gel in water; no placebo-controlled trial alone, and one 10-person constipation pilot of a four-ingredient formula.

Botanical name
Ulmus rubra
Part used
inner bark
Also called
Red elm, Indian elm, Gray elm, Ulmus fulva (older name)
Used in
Western herbalism
Taken for
The gut lining, Constipation, Indigestion, Reflux and heartburn
Sold as
powder, capsules, lozenges, tea

The plant

Slippery elm is the inner bark of Ulmus rubra, a tree native to eastern North America, named for the slimy feel of the bark when it is wet. The outer bark is stripped away and the inner layer is dried and milled to a pale, fibrous powder. Mixed with water, the powder swells into a thick, tacky gel, because the bark is rich in mucilage and also contains fiber and tannins.

The powder is stirred into hot or cold water as a drink or porridge, pressed into lozenges, or packed into capsules. It also turns up as one ingredient in blended gut products, which matters for the research: most of what has been tested in people is a formula containing slippery elm along with other ingredients, not the bark alone. The two studies we found used mixtures with lactulose and oat bran, or with aloe vera, curcumin, guar gum, pectin, peppermint oil and glutamine.

Slippery elm is also one component of Essiac, an herbal mixture promoted as an alternative cancer treatment; that use is outside this entry, and the cancer-center summary we cite states there is no evidence it treats cancer.

How the traditions use it

Western herbalism

North American peoples used slippery elm widely as a medicine. A US Department of Agriculture plant guide records that the Menomini took the inner bark as a tea for use as a physic, that the Dakota and Omaha-Ponca drank a decoction of the fresh inner bark as a laxative, that the Ojibwe used it for sore throats, and that several tribes applied the bark to sores and swollen glands. The guide adds that the knowledge was passed to early settlers, and that today the bark is sold in health food stores for sore throats, coughs and other bronchial ailments, and as a laxative. A reference source from a cancer center lists the traditional gut uses as gastrointestinal disorders and diarrhea, and notes that evidence for diarrhea is lacking.

What is in it

The relevant material is the mucilage, a viscous polysaccharide that was chemically described from the bark in 1946, together with fiber and tannins, according to a cancer-center herb summary. The summary attributes the demulcent (soothing, coating) action to the mucilage, a proposed bulk-laxative and transit-slowing action to the fiber, and an astringent action to the tannins. It also lists fatty acid esters (oleic and palmitic acid) with unclear antitumor activity. These are descriptions of the constituents and of laboratory-level proposals. We could not find a human study that measures a coating of the stomach or bowel lining by slippery elm.

What the human trials show

No placebo-controlled trial of slippery elm alone for a gut condition turned up in our searches. A 2020 systematic review of 33 double-blind placebo-controlled trials of Western herbal medicines in irritable bowel syndrome names peppermint oil, aloe vera, asafoetida, anise oil and several formulas in its abstract, and slippery elm is not one of them.

The human data are two small uncontrolled studies of formulas. In an open-label pilot of 31 people with IBS, a constipation-focused formula of powdered slippery elm bark, lactulose, oat bran and licorice root (10 people) increased bowel-movement frequency by 20% (P = 0.016) and reduced straining (P < 0.0001), abdominal pain (P = 0.032), bloating (P = 0.034) and global symptom severity (P = 0.0005). A second formula, for diarrhea-type IBS, contained slippery elm with bilberry, agrimony and cinnamon, and improved several symptoms without improving bowel habit. In a 16-week before-and-after study of 43 adults, a blend containing slippery elm, aloe vera, curcumin, guar gum, pectin, peppermint oil and glutamine was associated with 60% to 80% improvements in symptoms such as indigestion, heartburn and constipation.

Neither study had a placebo group or isolates the bark. A critical appraisal of popular remedies for esophageal symptoms lists slippery elm among herbal products of interest and concludes that anecdotal and empirical understanding remain far apart. A cancer-center summary states that evidence for slippery elm in diarrhea is lacking.

StudyDoseWhat it found
Open-label uncontrolled pilot, 10 people with constipation-predominant IBS (formula: slippery elm, lactulose, oat bran, licorice) PMID 20954962Formula taken in the pilot (amounts not in abstract)Bowel-movement frequency +20% (P = 0.016); straining, pain, bloating and global severity improved
Open-label uncontrolled pilot, 21 people with diarrhea-predominant or alternating IBS (formula: bilberry, slippery elm, agrimony, cinnamon) PMID 20954962Formula taken in the pilot (amounts not in abstract)Bowel habit not improved; pain, bloating, flatulence and global symptoms improved
16-week before-and-after study, 43 adults with digestive disorders (blend with slippery elm, aloe vera, curcumin, guar gum, pectin, peppermint oil, glutamine) PMID 321518785 g a day, then 10 g a day for 4 weeksSymptom frequency and severity improved 60% to 80% with no control group
Systematic review of 33 double-blind placebo-controlled trials of Western herbal medicines in IBS PMID 31987249VariousSlippery elm not among the preparations named in the abstract

How much the studies and the texts used

No dose of slippery elm has been tested alone for a gut outcome. The 16-week before-and-after study gave a multi-ingredient blend at 5 g a day, then 10 g a day for four weeks. The IBS pilot gave powdered bark mixed with lactulose, oat bran and licorice, and its abstract does not state the amount of bark. A US government plant guide records that the Dakota and Omaha-Ponca drank a decoction of fresh inner bark as a laxative, and the Menomini used a tea; no measured amount is given. We could not find a European monograph, WHO monograph or pharmacopoeial posology for slippery elm bark that we could cite.

Doses here describe what studies and pharmacopoeias used. They are not a recommendation for any person; a clinician or pharmacist who knows your medicines and conditions is the right person to ask.

Side effects and cautions

The two formula studies reported that their products were well tolerated, and neither flagged serious problems. Beyond that, the sources we could read are sparse. A cancer-center herb summary does not give side effects, pregnancy guidance or interactions for slippery elm, and the European herbal committee has not issued a monograph for it, so there is no regulator’s statement on pregnancy, breastfeeding or children to quote. We could not find a controlled safety study, a published case series or toxicology data for the bark taken by mouth. That is absence of data, not evidence of safety. People who are pregnant, breastfeeding or giving it to children are in a group the sources do not address.

Interactions

We could not find an interaction study of slippery elm with any medicine. The nearest guidance comes from a related mucilage herb: the European monograph on marshmallow root says the mucilage may delay the absorption of other medicines taken at the same time and advises a gap of half an hour to an hour. Slippery elm gel has the same physical character, though that has not been tested for this bark. The bark’s fiber is also described as capable of bulk-laxative and transit-slowing effects. The catalog’s own drug rules for slippery elm are listed automatically on this page.

Slippery elm on the shelf: the products that contain it

The products here name slippery elm among their actives. How much of it a serving holds, and whether that matches any trial, is on each page.

Inno Supps Inno Cleanse 4.1 out of 5 from 12,407 ratings from Amazon · $1.33 a day Dr. Berg Gallbladder Formula Extra Strength 4.4 out of 5 from 11,974 ratings from Amazon · ~$0.80 for a 2-capsule dose with a meal Nature’s Way Slippery Elm Bark Capsules 4.5 out of 5 from 11,033 ratings from Amazon · $0.34 a day Liver Medic Leaky Gut Repair 4.1 out of 5 from 3,474 ratings from Amazon · $1.00 per day at two capsules; the label’s advanced dose of four to six is $2.00 to $3.00 Terra Origin Healthy Gut Powder 4.3 out of 5 from 1,990 ratings from Amazon · $1.02 a day Totaria 5-in-1 Probiotic, Prebiotic and Postbiotic, 60 Billion CFU 4.5 out of 5 from 1,246 ratings from Amazon · $0.19 a day Clean Nutra GI Defend 4.4 out of 5 from 1,152 ratings from Amazon · $1.00 a day NanoRevive EsoRepair Esophageal & Stomach Liquid 3.9 out of 5 from 1,003 ratings from Amazon · $2.00 a day Arrae Bloat Capsules 4.1 out of 5 from 853 ratings from Amazon · $1.50 a day Organics Ocean Better Fiber with Psyllium Husk and Slippery Elm 4.4 out of 5 from 726 ratings from Amazon · $1.20 a day Soothe Naturals Stomach Soothe 4.1 out of 5 from 459 ratings from Amazon · $1.53 a day Terra Health Essentials Acid Relief 4 out of 5 from 452 ratings from Amazon · $1.63 a day

5 more entries list it; the full catalog is grouped by the job each product does.

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Often paired or compared

Western Marshmallow root Althaea officinalis Ayurvedic / TCM / Western Licorice Glycyrrhiza glabra Ayurvedic / Western Psyllium Plantago ovata TCM / Western Aloe vera Aloe vera (L.) Burm.f. (Aloe barbadensis Miller)

The questions that come up

Does slippery elm coat or heal the gut?

The mucilage in the bark forms a slippery gel in water, and that coating idea is the traditional rationale. We could not find a human study that measures a coating or healing effect. The human data are two small uncontrolled studies of formulas that contained slippery elm among other ingredients.

Is there a trial of slippery elm for constipation or IBS?

One open-label pilot gave a four-ingredient formula (slippery elm, lactulose, oat bran, licorice) to 10 people with constipation-predominant IBS, with a 20% rise in bowel-movement frequency. It had no placebo group and the formula had other laxative ingredients, so the bark’s share is unknown.

Is slippery elm the same as marshmallow root?

No. They are different plants, though both are rich in mucilage and both are used as soothing coatings. Marshmallow root has a European herbal monograph for mild gastrointestinal discomfort, while slippery elm has none and is traditionally North American.

Can slippery elm interfere with medicines?

We could not find a study on this. The European monograph for marshmallow root, another mucilage herb, advises a gap of half an hour to an hour from other medicines because absorption may be delayed. Whether the same applies to slippery elm bark has not been measured.

Sources