What is an allergy? Allergy is an immune response in which, after exposure to certain substances (such as pollen, food, bacteria, drugs, etc.), the immune system treats these substances as foreign invaders. At this time, the immune system produces antibodies to protect our body from harm. However, some people\’s immune systems can overreact to these substances, causing inflammation, irritation, and allergy symptoms. Common symptoms of allergies in children include skin