Allergies, also referred to as allergic diseases, are several situations caused by hypersensitivity of the immune system to normally harmless substances in the ecosystem. These diseases include hay fever, meals allergies, atopic dermatitis, allergic asthma, and anaphylaxis. Food intolerance and meals poisoning are separate conditions. Most common allergens consist of pollen and sure meals. Metals and other materials may also reason problems. Allergies symptoms may additionally consist of swelling, sneezing and an itchy, runny or blocked nose, itchy, red, watering eyes, wheezing, chest tightness, shortness of breath and a cough, a raised, itchy, red rash, swollen lips, tongue, eyes or face.