Why Allergic Reactions Happen
What causes allergic reactions?
One thing that makes the human body so amazing is its ability to defend itself against harmful substances and dangerous invaders, such as bacteria or viruses. However, in certain people, their body’s immune system is over sensitive and reacts defensively when exposed to allergens (generally harmless substances such as animal dander, dust, peanuts, mold, pollen or shellfish) by producing immunoglobulin E (IgE) antibodies. These antibodies attach to the receptors of a blood cell called a mastocyte (mast cell). When patients with an allergic disease (for example, asthma or allergic rhinitis) are exposed to an allergen[s], their immune system then rallies its defenses, launching a multitude of complex chemical weapons for an attack to destroy the supposedly identified “enemy.” What is happening in your body is that the allergens are binding to the IgE, which is attached to the mast cell (the main purpose of a mast cell is to destroy microorganisms invading your body). This triggers a reaction that allows the mast cells to release a variety of chemicals including histamine and leukotriene, which causes most of the symptoms of an allergy. Histamine attaches to receptors in blood vessels and causes them to enlarge. Histamine also binds to other receptors causing redness, swelling, itching and changes in secretions. During this process, unpleasant and in extreme cases life-threatening symptoms may be experienced.Content Created/Medically Reviewed by our Expert Doctors