Yerba santa is used for respiratory conditions including coughs, colds, tuberculosis, asthma, and chronic bronchitis. It is also used for fever and dry mouth. Some people use it to relieve muscle spasms, to loosen phlegm, and as a tonic. Yerba santa is sometimes applied directly to the skin in a warm dressing (poultice) to treat bruises, sprains, wounds, insect bites, and to relieve joint pain (rheumatism).