Common upper respiratory tract infections
Allergies are inappropriate responses by the body’s immune system to a substance that is not normally harmful. In some persons, the immune system wrongly identifies a nontoxic substance as an invader and the white blood cells overreact and do more damage to the body than to the invader. Thus, the allergic response becomes a disease in itself. Allergic rhinitis is an example of an unruly immune response to pollens in the upper respiratory tract.
Sinusitis is the blocking of the sinus passageways because of inflammation or excess mucus. Internet Photo