Medically reviewed on June 7, 2018
What is Slippery Elm?
The slippery elm tree is native to eastern Canada and eastern and central US, where it is found most commonly in the Appalachian mountains. The trunk is reddish brown with gray-white bark on the branches. In the spring, dark brown floral buds appear and open into small, clustered flowers at the branch tips. White elm (U. americana) is a related species used in a similar manner.
Ulmus rubra. Also known as U. fulva.
Slippery elm also is known as red elm, Indian elm, moose elm, and sweet elm.
What is it used for?
North American Indians and early settlers used the inner bark of the slippery elm not only to build canoes, shelter, and baskets, but as a poultice or as a soothing drink. Upon contact with water, the inner bark, collected in spring, yields a thick mucilage or demulcent that was used as an ointment or salve to treat urinary tract inflammation and was applied topically for cold sores and boils. A decoction of the leaves was used as a poultice to remove discoloration around blackened or bruised eyes. Surgeons during the American Revolution treated gun-shot wounds in this manner. Early settlers boiled bear fat with the bark to prevent rancidity. Late in the 19th century, a preparation of elm mucilage was officially recognized in the United States Pharmacopoeia.
Slippery elm prepared as a poultice coats and protects irritated tissues such as skin or intestinal membranes. The powdered bark has been used in this manner for local application to treat gout, rheumatism, cold sores, wounds, abscesses, ulcers, and toothaches. The tannins present are known to possess astringent actions. It also has been known to "draw out" toxins, boils, splinters, or other irritants.
Powdered bark is incorporated into lozenges to provide demulcent action (soothing to mucous membranes) in the treatment of throat irritation. It also is used for its emollient and antitussive actions, to treat bronchitis and other lung afflictions, and to relieve thirst.
When slippery elm preparations are taken internally, they cause reflex stimulation of nerve endings in the GI tract, leading to mucus secretion. This may be the reason they are effective for protection against stomach ulcers, colitis, diverticulitis, gut inflammation, and acidity. Slippery elm also is useful for diarrhea, constipation, hemorrhoids, irritable bowel syndrome, and to expel tapeworms. It also has been used to treat cystitis and urinary inflammations.
The plant also is used as a lubricant to ease labor, as a source of nutrition for convalescence or baby food preparations, and for its activity against herpes and syphilis.
What is the recommended dosage?
Slippery elm inner bark has been used for treatment of ulcers at doses of 1.5 to 3 g/day. It is commonly decocted with ethyl alcohol. No formal clinical studies support this dosage.
Contraindications have not yet been identified.
Documented abortive effects. Avoid use.
None well documented.
Extracts from slippery elm have caused contact dermatitis, and the pollen has been reported to be allergenic.
The FDA has declared slippery elm to be a safe and effective oral demulcent.