slippery elm

Slippery elm is a dietary supplement made from the inner bark of the North American slippery elm tree (Ulmus rubra), a deciduous tree native to the eastern and central United States and Canada. The inner bark is rich in mucilage, a gel-forming soluble fiber, and also contains tannins. It is sold as powders, capsules, lozenges, teas, and throat-coat-style products.

There is no dedicated fact sheet on slippery elm from the NIH Office of Dietary Supplements or NCCIH, and rigorous human studies are limited. The NIH/NLM LiverTox resource describes slippery elm's inner-bark mucilage as the presumed active component and notes it has been used orally for sore throat and digestive upset and topically for the skin, with roots in Native American traditional medicine — but it states that slippery elm is not approved as a treatment for any disease or condition. In short, these uses reflect traditional and folk practice rather than proven medical benefits, so slippery elm should not be assumed to treat or cure any condition. Talk with a clinician before relying on it for any health problem.

There is no established or government-recommended dose for slippery elm, and products differ widely by form (lozenge, capsule, powder, or tea). Follow the directions on the specific product label and, because standardized dosing and supporting evidence are lacking, talk to your doctor or pharmacist before starting it — especially if you are pregnant, breastfeeding, or considering it for a child.

Slippery elm has a long history of use and is generally recognized as safe for most adults when used short-term as directed; the NIH/NLM LiverTox resource reports no published cases of liver injury linked to it and rates it an unlikely cause of liver harm. However, there is little rigorous safety data in many populations, and it has not been formally evaluated for safety by US government supplement authorities across all groups. Pregnant or breastfeeding people, and anyone with a chronic condition, should check with a clinician first. As with all supplements, the FDA does not review these products for safety and effectiveness before they are sold.

Reported side effects are uncommon and usually mild; the gel-forming fiber may cause stomach upset, and allergic reactions — including skin reactions — have rarely been reported. Because formal safety data is limited, stop use and seek care if you develop a rash, swelling, trouble breathing, or other concerning symptoms.

Because slippery elm's mucilage coats the digestive tract, it could in theory slow or reduce the absorption of medicines taken at the same time, so it is often suggested to separate it from other drugs by a couple of hours. Formal interaction data is limited, so review your full medication and supplement list with a pharmacist or doctor before combining them.