Substances like dust, pollen, food and medications may be identified as harmful substances by the immune system, which causes the allergens within the body to attack. This results in an array of symptoms, such as a runny nose, post-nasal drip, coughing, and swollen glands. An allergy can spontaneously emerge at any age with little forewarning, which is why hair dye always advises completing a strand test before application.
More significant symptoms include hives, rashes and difficulty breathing. Any sort of sudden breathing difficulties should be treated immediately.Learn more about Allergies