During an allergic response, the immune system mistakenly identifies harmless substances, known as allergens, as foreign invaders. This triggers an immune response where the body starts to attack healthy tissues, believing they are foreign invaders. This immune response can lead to various symptoms such as inflammation, itching, sneezing, and difficulty breathing. In severe cases, it can even be life-threatening, causing anaphylaxis, a severe allergic reaction that can result in a drop in blood pressure, difficulty breathing, and loss of consciousness.