Itchy and swollen eyes can be caused by infections, allergies, overuse of eyes and other reasons. 1. Infection: Itchy and swollen eyes may be caused by bacteria, viruses, chlamydia and other types of pathogens. Pathogen infection of the eye leads to acute inflammatory lesions of the conjunctiva, cornea and other tissues, capillary permeability increases, a large number of inflammatory substances exudate, so the eyes itchy and swollen. 2. Allergy: eye surface contact with dust, pollen, hair, dander, mosquito bites and other allergenic stimuli, triggering an allergic reaction, lid conjunctiva and other tissues can appear edema, congestion, itching and other allergic symptoms. 3. Excessive eye use: excessive eye use caused by prolonged staying up late, long time studying and reading, and too dark or too strong light in the eye environment can also cause itchy and swollen eyes. Itchy and swollen eyes may be related to a variety of factors, if the rest is not relieved, it is recommended to consult a doctor as soon as possible to confirm the diagnosis.