An allergy is an adverse reaction by your body’s immune system to a substance that does not bother other people who are not allergic to it.
Any substance that triggers an allergic reaction is called an allergen. Some common allergens are pollen, dust mites, mold spores, pet dander, latex, various foods, insect stings and certain medicines. An allergic reaction can affect the nose, lungs, throat, sinuses, ears, lining of the stomach or the skin. It can cause a variety of symptoms, such as a runny nose, sneezing, itching, watery eyes, red eyes, wheezing, hives, flaky skin, skin rashes, shortness of breath, swelling or asthma. These symptoms can range from minor to severe and mostly depend on the allergen.