Slippery elm (also known as red elm, moose elm, Indian elm, gray elm, or soft elm) is a deciduous tree native to the eastern half of the United States and adjacent areas of southern Canada. Growing up to 40 meters in height, slippery elm has alternate, elliptical, doubly serrated leaves, which are dark, glossy green on top and paler and slightly fuzzy underneath. Slippery elm flowers from March to May, bearing small, bright red clusters shortly before the leaves open. The fruit, which matures from May to June, shortly after the leaves appear, is flat and almost disc-shaped, measuring roughly 15 mm in diameter. The tree has a thick, dark, reddish-brown outer bark, which may be deeply furrowed, and a whitish, mucilage-rich inner bark, which is used for health promoting purposes.
Slippery elm bark contains a mucilage composed of various sugars, including pentosans, methyl pentosans, and hexosan, which has a soothing effect on mucous membranes.
Recommended dosages for slippery elm vary widely with intended use and form of delivery (i.e. teas, lozenges, tinctures, or capsules). Most slippery elm products have dosage recommendations printed on the labeling. Slippery elm bark appears to be very safe, and there are no known health hazards or side effects associated with proper administration of designated therapeutic dosages.