Aphthous are erosions, that is, cavities in the mucous membrane, on the soft tissues of the mouth (most often on the inside of the cheek, lips or surface of the tongue). Aphthous on the lips often arise after mechanical damage, e.g. by an orthodontic apparatus. Aft support products are available without a prescription. Most often they occur in the form of an ointment or gel, due to the easy application. Preparations in the form of liquid or aerosol are also available.