Allergies

An allergic reaction occurs when the immune system misinterprets a non-toxic substance, such as grass, pollen, detergent, or food, as a harmful invader. The immune system responds to this supposed threat, called an allergen, by releasing various substances such as histamine. These substances cause a wide range of physical reactions, including respiratory and nasal congestion, increased mucus production, skin rashes, and conjunctivitis, among others.