Abstract: Methods and compositions for forming protective and/or medicated films on body tissue. Liquid compositions contain a hydrophobically modified polymer, other than an esterified lower-hydroxyalkyl-substituted cellulose, suspended or dissolved in a solvent. The modified polymer is soluble in the solvent but insoluble in body fluids. The compositions may optionally contain a separate medicinal component, i.e., one which is present in addition to any medications, if any, present in the solvent, in the modified polymer and in any other additive components such as flavors, skin penetrants, preservatives, other solvents for the additives, etc. A protective and/or medicated film is formed in situ upon body tissue by applying the liquid composition to the tissue and separating the solvent from the composition, e.g., by vaporization.