Concentrated potassium nitrate has been used to lessen the pain caused by aphthous stomatitis. The problem with this approach is that it can have difficulty penetrating into the deeper layers of mucosae or skin, and for this reason, its beneficial affects are not routinely predictable. When dimethyl isosorbide is added to potassium nitrate in an aqueous hydroxyethyl cellulose gel, it enhances the capacity of potassium nitrate to more completely permeate these tissues and predictably promote rapid pain control and aphthae healing.