Red, swollen and itchy eyes may be caused by allergic conjunctivitis, keratitis and acute conjunctivitis. 1. Allergic conjunctivitis: When allergic body comes into contact with pollen or animal fur, it can lead to a specific reaction in the eyes, resulting in redness, swelling, itching and other symptoms. In addition, skin care products, cosmetics, shampoos, hair dyes, etc., may also trigger an allergic reaction, resulting in red, swollen and itchy eyes. 2. Keratitis: When the eyes are infected by bacteria, resulting in keratitis, it can also cause redness, swelling, hot pain, itching and other symptoms. 3. Acute conjunctivitis: when the eyes are infected by microorganisms, it is easy to cause acute conjunctivitis. Acute inflammation of the conjunctival tissue occurs, which leads to an increase in eye secretions, and can also cause itching and swelling of the eyes. When the eyes appear red, swollen and itchy, you should pay attention to eye hygiene, avoid rubbing the eyes with your hands, so as not to aggravate the symptoms. If the symptoms are serious, it is recommended to go to the ophthalmology department of the hospital in a timely manner to clarify the cause of the disease and carry out targeted treatment.