Mucilage content of Slippery Elm puts it in the class of “antitussive” herbs – meaning it is capable of suppressing and relieving coughing and other upper-respiratory complaints.It has also been found to be highly effective against sore throats. One study found that an extract of Slippery Elm killed the Streptococcus pyogenes microbe that can cause a sore throat.3Slippery Elm bark is a common ingredient in herbal remedies for coughs, colds and bronchitis, combining well with marshmallow root, liquorice and boneset herbs Used to make a poultice to treat wounds, cuts, boils and insect bites. may be effective for soothing sore throat.