An allergy is a condition in which the body's immune system reacts abnormally to substances that are generally considered harmless. These substances are known as allergens, and they can come from a variety of sources such as food, pollen, pet dander, or insect bites. When a person is exposed to an allergen, their immune system produces antibodies, leading to the release of histamine and other chemicals in the body. This reaction can cause symptoms such as itching, redness, swelling, runny nose, coughing, difficulty breathing, and in severe cases, anaphylaxis. The severity of an allergy can vary from person to person and can range from mild to life-threatening.
