Antihistamine drugs help to block the effects of histamine. A type of antibody that is produced when one is exposed to an allergen. This type of antibody takes part in allergic inflammation. Leukotrienes - Substances produced by mast cells during an allergic reaction. Pollen - Microscopic particles from the male flower that can fertilize the female flower to produce seed.
Allergenic pollen is usually from wind-pollinated plants.
Sinusitis - Infection in the cavities of facial bones. Symptoms include pressure or pain around or below the eyes, persistent yellow nasal discharge, mucus drainage in the throat, and nasal stuffiness. Urticaria - Hives. A rash consisting of irregularly shaped itchy wheals that come and go within a 24 hour period. Chronic urticaria is urticaria that persists for 3 or more months continuously, usually with no obvious external cause, and sometimes found to be due to an autoimmune process in the body.