Marshmallow (Althea officinalis) is a plant. The leaves and the root are sometimes used to make medicine.
Marshmallow is sometimes used to form a protective layer on the skin and lining of the digestive tract. It also contains chemicals that might decrease cough and fight infections. Don't confuse marshmallow with the mallow (Malva sylvestris) flower and leaf.
Marshmallow leaf and root are commonly used by mouth for stomach ulcers, diarrhea, constipation, and other conditions, but there is no good scientific evidence to support these uses.