The mucilage of slippery elm gives it a soothing effect for coughs. Usnea also contains mucilage, which may be helpful in easing irritating coughs. There is a long tradition of using wild cherry syrups to treat coughs. Other traditional remedies to relieve coughs include bloodroot, catnip, comfrey (the above-ground parts, not the root), horehound, elecampane, mullein, lobelia, hyssop, licorice, mallow, (Malvia sylvestris),red clover, ivy leaf, pennyroyal (Hedeoma pulegioides, Mentha pulegium),onion, (Allium cepa), and plantain (Plantago lanceolata, P. major). None of these has been investigated in human trials, so their true efficacy for relieving coughs is unknown.

Mullein is classified in the herbal literature as both an expectorant, to promote the discharge of mucus, and a demulcent, to soothe and protect mucous membranes. Historically, mullein has been used as a remedy for the respiratory tract, particularly in cases of irritating coughs with bronchial congestion.² Other herbs commonly used as expectorants in traditional medicine include elecampane, lobelia, yerba santa (Eriodictyon californicum),wild cherry bark, gumweed (Grindelia robusta),anise(Pimpinella anisum), and eucalyptus. Animal studies have suggested that some of these herbs increase discharge of mucus.³ However, none have been studied for efficacy in humans.