Patients with sudden swelling below the eyes need to be treated according to the cause, which may be caused by insect bites, blepharitis, trauma and so on, and can be treated by medication and physical therapy. 1. Insect bites: If a mosquito bites a patient under the eye, it can cause sudden swelling under the eye, accompanied by eyelid swelling, itching and other uncomfortable symptoms. The patient can perform local cold compresses, but also follow the doctor’s instructions to use soapy water to wash the eyelids, the use of erythromycin ophthalmic ointment and other medication, to promote the recovery of the condition. 2. Blepharitis: Blepharitis refers to purulent inflammation of the eyelid glands, and patients can experience swelling, pain, congestion and other symptoms, patients can follow the doctor’s instructions to use gentamycin ophthalmic ointment, levofloxacin eye drops and other medications, to control the inflammation, and to promote the recovery of the condition. 3. Trauma: If the patient’s eyes are squeezed or hit by external forces, causing soft tissue edema, it can lead to sudden swelling under the patient’s eyes. The patient’s eye trauma early feasible 48 hours of cold compresses, 48 hours after the feasible eye local hot compresses. It is recommended that patients with sudden swelling under the eye and other discomforts should consult a doctor to evaluate their condition and follow the doctor’s instructions.