An allergy is a reaction of our immune system to a foreign substance, also called an allergen. Examples of the types of substances that often cause an allergy are pollen, dust mites, mold, pets or food components such as peanuts.
When these allergens come into contact with our skin, mucous membranes or eyes or if they enter the body through our respiratory tract or mouth, our immune system sometimes reacts with an 'too exaggerated' reaction. This reaction aims to make allergens harmless. Unfortunately, this is accompanied by complaints such as a runny nose, watery eyes, itching, shortness of breath and possibly diarrhoea. These are all kinds of reactions of our immune system to an allergen.