In an embodiment, a barrier-forming composition includes a carbohydrate gum, a humectant, and an antimicrobial agent. The composition furthermore meets the following requirements: about 0.01% = C = about 0.4%； about 4.5% = H = about 65%； and 0.050% = A； or about 0%= C <； about 0.4%； about 55% = H = about 65%； and 0.050% <； A. C is the carbohydrate gum； H is the humectant； and A is the antimicrobial agent. All percentages are by weight of the total composition. In an embodiment the barrier-forming composition has an Rf value in water of 0 to about 0.25. A method of making and administering the barrier- forming composition to block, neutralize, or kill microorganisms is also provided.
