Allergic conjunctivitis is an allergic reaction on the surface of the eyes.
Pollen, cat dander, and smoke are examples of such substances. The allergens may be in the air, such as smoke or plant pollen. Or they might be on your hands and get into your eyes when you touch your eyes. The symptoms are itchy, watery eyes that are often red and sometimes swollen. Both eyes are affected unless just one eye came into contact with the allergen, as might happen with poison ivy.