Allergies that can cause swollen eyes, as well as red and itchy eyes, include dust mites, allergic rhinitis, pet dander, pollen allergies, makeup reactions, perfume reactions, chemical reactions and contact lenses reactions. Most eye allergies are not dangerous and do not cause permanent damage, reports the American Academy of Allergy, Asthma and Immunology.
Allergies are also not contagious. It is important for persistent swollen eyes, red eyes or itchy eyes to be examined by an eye professional, as it can be a symptom of a threatening disease and not an allergy, notes the American Academy of Allergy, Asthma and Immunology. To help soothe eyes inflamed from allergies, it is recommended to wash the face, rinse or flush the eyes with water, use allergy eye drops and use a cold compress to help with the swelling, reports Everyday Health.