One of the most remarkable aspects of the human body is its ability to ward off invaders like viruses and bacteria. Sometimes, however, a person’s body overreacts to an otherwise harmless substance like pollen, dust, or mold, and creates an antibody called immunoglobulin E (IgE) – this is called an allergy. When patients with allergic diseases are exposed to allergens, their immune systems react as though fighting off an invader. During this reaction, uncomfortable symptoms may occur, which may become life-threatening in extreme cases.