It is considered the “most diuretic of the mucilages” and “the most mucilaginous of the diuretics.” This illustrates its strongest note as a demulcent for the urinary tract. It is useful for inflammation of the bladder, hematuria, retention of urine, some forms of gravel, and in nearly every affliction of the kidney and bladder.

It has also been employed for inflammation of the gastrointestinal tract. The root has been used as a demulcent (but not as an expectorant) to soothe mucous membranes of the throat and as a cough suppressant. Marshmallow is used specifically for soothing the mucous membrane of the urinary tract and to a lesser degree the gastrointestinal tract. Externally, the root is used as part of many soothing poultices. Marshmallow is valuable, in the form of decoction, in diseases of the mucous tissues: hoarseness, catarrh, pneumonia, gonorrhea, catarrh, renal irritation, acute dysentery, and diarrhea. The root counters excess stomach acid, peptic ulceration, and gastritis. Even though the root is used most often, an infusion of the leaves is used to treat cystitis and frequent urination.