Allergic rhinitis is inflammation of nasal airways caused by an allergen, such as pollen, dust, mould or certain animal danders. Allergic rhinitis often causes cold-like symptoms, such as sneezing, itchiness and a blocked or runny nose. These symptoms usually start soon after being exposed to an allergen. Some people only get allergic rhinitis for a few months at a time because they are sensitive to seasonal allergens, such as tree or grass pollen. Other people get allergic rhinitis all year round.
Allergic rhinitis is caused by the immune system reacting to an allergen as if it were harmful. The immune system is the body's natural defense against infection and illness. If your immune system is oversensitive, it will react by attacking allergens in the same way it attacks viruses and infections. Known allergens include pollen, house dust mites and certain animals.
Note: We are giving only a brief description of each disease for your quick reference with some best related photographs where needed.