Viral conjunctivitis
Conjunctivitis is a common condition that causes redness and inflammation of the thin layer of tissue that covers the front of the eye (the conjunctiva).
People often refer to conjunctivitis as red eye.
Other symptoms of conjunctivitis include itchiness and watering of the eyes, and sometimes a sticky coating on the eyelashes (if it's caused by an allergy). Conjunctivitis can affect one eye at first, but usually affects both eyes after a few hours.