Dust mite allergy, also known as house dust allergy, is a sensitization and allergic reaction to the droppings of house dust mites. The allergy is common [54] and can trigger allergic reactions such as asthma, eczema, or itching. Signs and symptoms of allergic reactions include shortness of breath, itching, watery eyes, fatigue, and wheezing. An allergic reaction is the body's way of responding to an invader. When the body senses a foreign substance, called an antigen, the immune system is triggered. Learn about different types of allergies, allergic reactions, their types, symptoms, and severity. Many people suspect they have allergies. Learn about allergen types, common allergy signs and symptoms, how to get diagnosed and available treatment options. What is an allergic reaction? Allergic reactions are a set of symptoms that happen after you touch, inhale or eat something you’re allergic to. They can also happen after a bee sting. Examples of allergens that can set off allergic reactions include pollens, pets, dust, foods and medications. Allergies are your immune system’s overreaction to foreign substances. When you touch, inhale or eat something you’re allergic to, your body thinks it’s harmful and reacts to try to get rid of it. Allergies happen when the immune system reacts to a foreign substance that gets inside the body. These substances are known as allergens. They include pollen, bee venom and pet dander. Allergies also can happen due to certain foods and medicines that don't cause reactions in most people. Read about allergy treatment, symptoms, testing, shots, and medicine. Learn about the types of allergies (asthma, allergic rhinitis, seasonal, conjunctivitis, eczema, anaphylaxis, hives) causes, risk factors, and more. An allergic reaction typically triggers symptoms in the nose, lungs, throat, sinuses, ears, lining of the stomach or on the skin. For some people, allergies can also trigger symptoms of asthma. Allergic reactions can affect your eyes, skin, breathing or more. If you were having one, would you know it? WebMD tells you what you need to know.