Allergy: Signs and Symptoms

Allergy is an immune system reaction to substances that are usually harmless. Signs and symptoms of an allergic reaction vary from person to person and range from mild to severe. Common signs and symptoms of an allergic reaction include sneezing, itching, watery eyes, and a runny or blocked nose. More severe allergic reactions can cause anaphylaxis, a potentially life-threatening condition that requires immediate medical attention. Knowing the signs and symptoms of an allergic reaction is important for people who have allergies, as it can help them take steps to prevent anaphylaxis.