The most common allergy symptoms can range from watery eyes, runny nose, sneezing, a rash or hives or other more serious symptoms, like trouble breathing and swelling in your mouth or throat, or could even be a life-threatening reaction called anaphylaxis.
An allergy occurs when the body’s immune system sees a harmless substance as a germ and overreacts to it. The substances that cause allergic reactions are allergens.
To protect your body from the allergens, your immune system produces IgE antibodies that attack the allergens. The symptoms that result are an allergic reaction.
Pollens, dust mites, insect venom and food such as nuts or shellfish are also common substances that people are allergic to.