When symptoms like a runny nose, continuous sneezing and coughing, or itchy body rashes are making your life miserable, it often means you are suffering from an allergy. Your body shows symptoms of allergy when it is trying to fight external allergens. Of the several factors that cause allergies, the most common ones are food products like milk, soy,, dairy products, peanuts etc, external atmospheric factors like smoke, dust or pollution or other kinds of allergens like dog fur, pollen or even some medicines.