Sudden redness and swelling of the upper eyelid overnight can be caused by infection or allergy.
Infections in the upper eyelid area are a common cause of eyelid redness and swelling, such as blepharitis and acute cellulitis of the eyelids, which can be characterized by redness, swelling, heat and pain around the eyelids.
Allergic factors can also cause sudden redness and swelling of the upper eyelids, which may usually be accompanied by localized itching sensations, related to eye contact with cosmetics, hair dyes, shampoos, pollen and other allergens, such as contact blepharitis, spring keratoconjunctivitis, and so on.
It is difficult for patients to determine on their own which condition is causing the problem, and they need to go to the ophthalmology department of the hospital to clarify the cause of the problem and follow the doctor’s instructions for treatment.