The sudden swelling of the lower eyelid like an eye bag indicates that the formation of swelling is short-lived and is generally related to lack of sleep, inflammatory stimulation, allergies, and body edema, which manifests itself as loose eye skin and sagging fat in the shape of a bag. 1. Lack of sleep: The human body suffers from lack of sleep when it stays up late or has insomnia, and when the body does not get sufficient rest, many discomforts of the body occur, which also include Lower eyelids appear swollen like bags under the eyes. Generally the symptoms will improve after rest, you can carry out appropriate ice packs to eliminate edema or massage the eyes to promote blood circulation; 2. Edema: When you wake up in the morning, the body’s electrolytes are disturbed and more metabolic substances are discharged from the body, it will cause edema of the eyes or face. You can drink some corn husk tea or black coffee, etc., to speed up the metabolism and help remove the edema; 3. Inflammatory irritation: inflammatory irritation may be caused by exposure to a certain allergen, and inflammation occurs as redness, swelling, and heat, such as blepharitis, which can make the lower eyelid swell if the inflammatory factor continues to stimulate it; 4. Allergy: the lower eyelid suddenly swells like a bag under the eye may be the result of an inflammatory infection in the eye, or exposure to some kind of allergen, and if the patient rubs the eyes with unclean hands, it will aggravate the allergy symptoms. If there is redness, swelling, itching and other symptoms, you should go to the hospital in time for examination to identify the allergens and treat them properly. Note: In general, it is important to get enough sleep, use antibiotics for anti-inflammation, develop a good routine, and do not drink too much water before going to bed; avoid contact with allergens that cause eye swelling, apply some anti-inflammatory ointment to relieve symptoms, and seek systematic treatment from a doctor if necessary.