Slippery Elm Benefits, Marshmallow Root and DGL: What Works

Slippery elm benefits are mostly plausible rather than proven. Its inner bark is rich in mucilage, a gel-forming fiber that can coat an irritated throat, and the FDA accepts elm bark lozenges as an oral demulcent for sore throat^[1]. For reflux, IBS or gut health, we found no trial of slippery elm on its own, and reviews rate the human evidence as lacking^[2][3].

Marshmallow root has the same coating mucilage and an official European listing for mild stomach discomfort, based on traditional use rather than trials^[4]. DGL (deglycyrrhizinated licorice) works differently and has the best data of the three: a 200-person placebo-controlled reflux trial^[5]. Below: what each herb does, what the studies actually tested, the doses they used, and who should skip them.

Get medical help promptly if reflux or stomach pain comes with trouble swallowing, unexplained weight loss, vomiting, bleeding (vomited blood or black stools) or signs of anemia. Reflux guidelines treat these as alarm symptoms that need an endoscopy soon, not a home remedy^[6].

Slippery elm, marshmallow root and DGL at a glance

All three are sold as "gut-soothing" herbs, but they act in different ways and carry very different evidence.

What is slippery elm good for?

Soothing a sore throat is the best-supported use. Slippery elm is a tree native to the eastern and central United States and Canada, and its inner bark is used for sore throat, stomach upset and skin irritation^[7]. The FDA's over-the-counter monograph lists elm bark as a demulcent for "temporary relief" of sore mouth and sore throat, in lozenges containing 10 to 15 percent elm bark^[1].

The mucilage is the working part. Its polysaccharides turn viscous in water, which is thought to coat mucous membranes, and its fiber is thought to act as a bulk-forming laxative. Memorial Sloan Kettering's herb database still rates human data as lacking for cough, diarrhea and most other claimed uses^[3].

Slippery elm for IBS and constipation

The IBS evidence comes from blends, not slippery elm alone. In an open-label pilot of 31 people with IBS, a formula of slippery elm, lactulose, oat bran and licorice raised bowel movement frequency by 20% in the constipation group and eased straining, pain and bloating^[10]. That arm had 10 people and no placebo.

A second formula for diarrhea-type IBS (bilberry, slippery elm, agrimony and cinnamon) did not normalize bowel habit, though pain, bloating and flatulence improved^[10]. Because the blend also held lactulose and oat bran, the constipation results cannot be credited to the bark alone. For constipation or IBS, strain-specific probiotics have far more trial data; see our guide to probiotics for IBS.

Slippery elm for gastritis and gut lining

Evidence for slippery elm alone is limited to lab work. In inflamed colon biopsies from people with ulcerative colitis, slippery elm scavenged free radicals and reduced oxygen radical release, a result the authors said merits formal testing^[15]. No human trial has tested slippery elm for gastritis, ulcers or leaky gut.

A 16-week study of 43 adults did report less heartburn, indigestion and bowel symptoms, better intestinal permeability scores and more Faecalibacterium prausnitzii on a formula that included slippery elm^[11]. The formula also held curcumin, aloe vera, guar gum, pectin, peppermint oil and glutamine, and the study had no control group.

Can slippery elm heal GERD or heartburn?

There is no evidence that it heals gastroesophageal reflux disease (GERD); at most it may ease the burn for some people, and that has not been tested properly. A critical review of popular remedies for esophageal symptoms, slippery elm and licorice included, found a "substantial gap" between anecdotal and measured benefit^[2].

In the one study with reflux outcomes, almost half of the participants who used proton pump inhibitors no longer needed them by the end^[11]. That was a seven-ingredient formula without a placebo group, so it says little about slippery elm itself.

Guidelines take a different first step. For classic heartburn and regurgitation without alarm symptoms, the American College of Gastroenterology recommends an 8-week trial of a once-daily proton pump inhibitor taken before a meal. Its lifestyle measures are weight loss if overweight, no meals 2 to 3 hours before bed, avoiding tobacco and trigger foods, and raising the head of the bed for nighttime symptoms^[6]. Our GERD page covers causes and other options.

What does marshmallow root do for the gut?

It is a demulcent with official recognition but no gut trials. The European Medicines Agency lists marshmallow root as a traditional herbal medicine for mild gastrointestinal discomfort and for throat irritation with dry cough. "Traditional" means the listing rests on long-standing use, not on proof of efficacy^[4].

In lab tests, marshmallow root extract and its polysaccharides stimulated the vitality of human epithelial cells and formed bioadhesive layers on cell surfaces^[9]. That supports the idea of a protective coating, but it was measured in cell culture.

For stomach use, the EMA monograph gives adults 2 to 5 g of root soaked as a macerate in 150 ml of water, three times daily, up to 15 g a day. It advises seeing a doctor if symptoms last more than 2 weeks and does not recommend it under age 12 or in pregnancy and breastfeeding, for lack of data^[4].

Slippery elm vs. marshmallow root

They are close substitutes. Both rely on mucilage, both are mainly throat and stomach demulcents, and neither has a placebo-controlled gut trial on its own^[3][4]. Marshmallow root has the clearer dosing and safety labeling; slippery elm has the FDA lozenge listing^[1].

What does DGL licorice do for you?

DGL is licorice root with most of its glycyrrhizin removed, used mainly for reflux, indigestion and ulcers. Glycyrrhizin is the compound linked to high blood pressure, low potassium and heart rhythm problems, so removing it is the point^[13][16]. DGL's remaining flavonoids are thought to increase mucus production and blood flow to the stomach lining rather than reduce acid^[8].

DGL licorice for heartburn and regurgitation

The best trial is recent. In a double-blind trial, 200 adults with reflux symptoms took GutGard, a flavonoid-rich deglycyrrhizinated extract, at 75 mg twice daily after meals, or placebo, for 28 days. The extract group reported better quality of life and earlier relief of heartburn (by day 14) and regurgitation (by day 7)^[5].

Read it with care. The manufacturer sponsored the trial and supplied the product, and planned pH and sphincter-pressure tests were dropped, so all results are self-reported^[5]. An earlier placebo-controlled trial of the same extract (75 mg twice daily for 30 days) reduced functional dyspepsia symptoms by days 15 and 30^[12].

DGL for stomach ulcers

Most ulcer data are decades old. A 2020 review summarizes a one-month trial in 33 people with gastric ulcers: DGL at 760 mg three times daily shrank ulcers by 78%, versus 34% on placebo, and 44% versus 6% healed completely^[8]. In a 1979 study, 350 mg of DGL taken with each aspirin dose reduced aspirin-related fecal blood loss^[17]. These were small, older studies; peptic ulcers need a diagnosis and medical treatment, not self-care with supplements.

The same review notes that DGL capsules were not shown to work in ulcer trials and that chewable tablets taken 20 minutes before meals were used instead^[8]. The newer reflux trial used capsules after meals^[5], so the "must be chewed" rule rests on old data and is not settled.

Do these herbs affect the gut microbiome?

In a test tube, yes; in people, unknown. When researchers added slippery elm or licorice root to cultured stool from 12 healthy donors, roughly a third of 299 bacterial species shifted in abundance. Bifidobacterium, Lactobacillus and Bacteroides species rose, while potential pathogens such as Citrobacter freundii and Klebsiella pneumoniae fell^[18].

Slippery elm significantly increased bacteria that make butyrate, a short-chain fatty acid, while licorice gave the largest rise in propionate producers. The licorice used was whole root, not DGL, and the authors expect effects in the body to be smaller than in culture^[18].

How to take them: doses used in studies

We found no gut trial that tested a dose of slippery elm alone^[3], so the figures below come from regulators, blended-formula studies and reviews. For slippery elm powder, capsules or tea, follow the product label.

Take mucilage herbs apart from medicines. The EMA advises not taking marshmallow root within 30 to 60 minutes of other medicines because it may delay their absorption^[4]. Slippery elm's mucilage forms a similar viscous gel^[3], so ask a pharmacist how to space it around any prescription.

Who should avoid slippery elm, marshmallow root or DGL?

Most people can use slippery elm and marshmallow root with little risk; DGL needs more care. Slippery elm preparations are generally recognized as safe, with no evidence of liver injury^[7]. The EMA lists no known side effects for marshmallow root; its only contraindication is an allergic reaction to the plant^[4].

Licorice is different. In a meta-analysis of 18 studies, regular intake of at least 100 mg of glycyrrhizin a day raised systolic blood pressure by about 5.5 mmHg and lowered potassium^[16]. "Deglycyrrhizinated" does not always mean zero: GutGard is standardized to no more than 3% glycyrrhizin^[5]. One case report describes high blood pressure, low potassium and fainting after years of heavy DGL use^[14].

Talk to a clinician before using these herbs if you:

• take any regular oral medicine, because mucilage may slow its absorption^[4];
• have high blood pressure, heart or kidney disease, or a high-salt diet (licorice products)^[13];
• take corticosteroids, which interact with licorice^[13];
• are pregnant or breastfeeding: large licorice intake during pregnancy is unsafe, and marshmallow root is not recommended for lack of data^[13][4].

When to see a doctor

See a clinician rather than trying another herb if:

• you have trouble or pain swallowing, unplanned weight loss, vomiting, black stools or vomited blood, or are told you have anemia^[6];
• heartburn and regurgitation keep coming back: guidelines use a supervised 8-week medication trial, then endoscopy if symptoms do not respond^[6];
• stomach symptoms last more than 2 weeks on marshmallow root or similar remedies^[4];
• a sore throat is severe, lasts more than 2 days, or comes with fever, headache, rash, nausea or vomiting^[1];
• you notice palpitations, an irregular heartbeat, fainting or rising blood pressure readings while taking a licorice product^[13][14].

For other gentle options, see what the evidence shows for ginger and for peppermint, ginger and fennel teas.

This article is for general educational purposes and is not medical advice. Slippery elm, marshmallow root and DGL are not substitutes for diagnosis or prescribed treatment of reflux, ulcers or bowel disease. Talk to a qualified healthcare professional before using them, particularly if you are pregnant, immunocompromised, taking prescription medication, or managing a diagnosed condition.