Eyelid swelling in one eye may be caused by physiological reasons, and may also be related to pathological reasons, such as blepharitis and eye allergy. 1. Physiological reasons: staying up late, drinking a lot of water before going to bed and other physiological factors can cause patients with eyelid swelling, usually do not need special treatment, the eye can subside after rest. 2. Blepharitis: blepharitis refers to purulent inflammation of the eyelid glands, patients in the inflammatory stimulation, patients can appear eyelid abscess, often occurring in one-sided eyes. Patients need to follow the doctor’s instructions to use tobramycin eye drops and other drugs to control inflammation and promote recovery. 3. Allergy: If the patient’s eyes are bitten by mosquitoes or contacted with pollen, hair and other allergens, the body is allergic, which can lead to the patient’s one side of the eye allergy and swelling. It is recommended that patients with obvious swelling of one side of the eye should consult a doctor in time to assess their condition and follow the doctor’s instructions for treatment.