Medically reviewed by Jurairat J. Molina, MD Allergies are an immune system reaction to substances called allergens. The ...

This heightened reaction is typically directed against harmless antigens, leading to unintended tissue damage. There are four main types of hypersensitivity reactions: Type I, which involves ...

ALLERGIC rhinitis (AR) is a prevalent upper airway condition caused by an IgE-mediated type 1 hypersensitivity reaction to ...