The dried inner bark of the slippery-elm tree was a favorite of many Native American tribes, and was subsequently adopted by European colonists. Like marshmallow and mullein, slippery elm was used as a treatment for sore throat, coughs, dryness of the lungs, inflammation of the skin inflammations, wounds, and irritation of the digestive tract.1 It was also made into a kind of porridge to be taken by weaned infants and during convalescence from illness: various heroes of the Civil War are said to have credited slippery elm with their recovery from war wounds.
Slippery elm has not been scientifically studied to any significant extent. It's primarily used today as a cough lozenge, widely available in pharmacies. Based on its soothing properties, slippery elm is also sometimes recommended for treating irritable bowel syndrome, inflammatory bowel disease (such as Crohn's disease and ulcerative colitis), gastritis, esophageal reflux (heartburn), and hemorrhoids. However, there is no meaningful evidence that it is helpful for any of these conditions.
Suck cough lozenges as needed. For internal use, a typical dose is 500 to 1,000 mg of 3 times daily.
Other than occasional allergic reactions, slippery elm has not been associated with any toxicity. However, its safety has never been formally studied. Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.