Amlexanox - The active ingredient in Aphthasol. That acts as a potent inhibitor of mast cells which mediate allergic response.

Antihistamine - Anything used to counteract the physiological effects of histamine.

Canker Sores - Shallow, painful sores found in the mouth that are usually red and may sometimes have a white coating over them. These often appear on the inside of the lips and cheeks, the base of the gums or under the tongue. Canker sores differ from fever blisters, which are usually on the outside of the lips or the corners of the mouth. Anyone can get canker sores, however, women, teens and people in their 20s suffer from canker sores most frequently. Canker sores are not contagious. Doctors do not know what causes canker sores, but they may be triggered by stress, poor nutrition, food allergies, menstrual periods and trauma.

Cold Sores - A.K.A. fever blisters/herpes are clusters of small blisters on the lip and outer edge of the mouth. The skin around the blisters is often red and inflamed. The blisters can break open, weep a clear fluid, and then scab over after a few days. Complete healing may take 7 to 10 days. Cold sores are contagious.

Histamine - A physiologically active depressor amine found in plant and animal tissue, derived from histidine by decarboxylation and released from cells in the immune system as part of an allergic reaction. It is a powerful stimulant of gastric secretion, constrictor of bronchial smooth muscle, and vasodilator.

Leukotrienes - Any of a group of physiologically active substances that possibly function as mediators of inflammation and as participants in allergic responses.

Mast Cell - A connective tissue cell whose normal function is unknown but which is frequently injured in allergic reactions, releasing chemicals including histamine that are very irritating and cause itching, swelling, and fluid leakage from cells. Also known as a mastocyte or labrocyte.

Mucoadhesive - An attribute indicating that a material will adhere to mucus. Muco-adhesive material is often used to deliver drugs to places containing mucus, such as the eye.

Prodromal Stage - The primary stage of certain infectious diseases during which prodromal symptoms appear. Also called incubation period, latent stage, incubative stage.

Recurrent Aphthous Ulcer (RAU) - A.K.A. Canker Sores are shallow, painful sores in the mouth that are usually red and may sometimes have a white coating over them. These often appear on the inside of the lips and cheeks, the base of the gums or under the tongue. Canker sores are different from fever blisters, which are usually on the outside of the lips or the corners of the mouth. Anyone can get canker sores; however, women, teens and people in their 20s suffer from canker sores most frequently. Canker sores are not contagious. Doctors do not know what causes canker sores, but they may be triggered by stress, poor nutrition, food allergies, menstrual periods and trauma.