Slippery elm (Ulmus fulva) has been used as an herbal remedy in the United States for centuries and is now enjoying greater popularity than ever. This plant has received recognition from the U.S. Food and Drug Administration as a safe and effective remedy for soothing throat and respiratory irritation. Herbalists also recommend it for suppressing coughs and, externally, for treating wounds and cuts. The mucilage, or gummy secretion, from the bark of the slippery elm is also considered a wholesome nutritional food, similar in texture to oatmeal.

Slippery elm is a small- to medium-sized tree native to North America. It can reach a height of 20 meters and is topped by spreading branches that form an open crown. The red-brown or orange branches grow downward, and the stalkless flowers are arranged in dense clusters. The plant's leaves are long and green, darkening in color during the fall. The bark has deep fissures, a gummy texture, and a slight but distinct odor.

The slippery elm's inner bark is used for medicinal purposes.

Slippery elm is used to treat the following conditions and symptoms:

• Sore throat
• Respiratory irritation
• Gastrointestinal conditions
• Ulcers

Traditionally, slippery elm has also been used as a skin softener and smoother, a cough medicine, and a nutritional food. It is used externally as a poultice to treat wounds, burns, and other skin conditions, as well as vaginitis (inflammation of the vagina, usually caused by infection) and hemorrhoids.

Commercial preparations are made from 10-year-old inner bark, or bast, sold in long flat pieces about two to three feet long, between 1/8 and 1/16 of an inch in thickness. Available forms include the following:

• Finely powdered bark for drinks (infusions and decoctions and liquid extracts)
• Coarsely powdered bark for poultices

Pediatric

• Adjust the recommended adult dose to account for the child's weight. Most herbal dosages for adults are calculated on the basis of a 150 lb (70 kg) adult. Therefore, if the child weighs 50 lb (20-25 kg), the appropriate dose of slippery elm for this child would be 1/3 of the adult dosage.

Adult

The following are recommended adult doses for slippery elm:

• Decoction (1:8) made from powdered bark, 4 to 16 mL three times per day; or 5 to 20 mL (1:10) taken as often as needed (can be added to juice or oatmeal)
• Infusions: 4 g powdered bark in 500 mL boiling water three times per day as nutritional supplement
• Capsules: 2 to 4 g three times per day in 500 mg capsules
• External application: Mix coarse powdered bark with boiling water for poultices 

There are no known health hazards reported for slippery elm when it is properly administered in recommended therapeutic doses.

Taking slippery elm with oral medications may decrease the absorption of these medications; therefore, ingestion of slippery elm several hours before or after other herbs or medications may be warranted.

No noteworthy interactions (positive or negative) between slippery elm and conventional medications are known to have been reported in the literature to date.

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Beveridge RJ, Stoddart JP, Szarek WA, Jones JK. Some structural features of the mucilage from the bark of Ulmus fulva (slippery elm mucilage). Carbohydr Res. 1969;9:429-439.

Blakley T. Slippery elm: Comparative study of the effects of plant spacing on plant development and yield. Research Farm Proposal No. 6088. Collaborating Team, The National Center for the Preservation of Medicinal Herbs. Project Period 1998–2008. Available at: http://www.ncpmh.org/6088.html.

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