Swollen eyes may be caused by eye diseases, allergic reactions, other systemic diseases and other factors, or it may be physiological reasons. 1. Eye diseases: due to bacterial, viral and other infections that cause inflammatory reactions in the eyes, there may be redness, swelling, heat, pain and other inflammatory reactions, common diseases such as erysipelas, folliculitis, etc.; after the eye tissues have been traumatized, the exudation of tissue fluids will be increased to cause the symptom of edema in the eyes. 2. Allergic reaction: mosquito bites, food, drugs and other factors may cause the body to produce an immune response, resulting in anaphylactic edema of the eye. 3. Other systemic diseases: renal system diseases can lead to sodium retention, causing eyelid edema, common diseases include glomerulonephritis, nephrotic syndrome, etc.; right heart failure due to the body’s circulation stagnation, ocular tissue reflux obstruction, resulting in edema; cirrhosis of the liver, hypoproteinemia, hepatocellular carcinoma, and other diseases can also lead to sodium retention, the emergence of the symptom of eyelid edema. 4. Physiological reasons: drinking a lot of water before going to bed can lead to the manifestation of edema in the eyes in the morning, which usually does not need special treatment and will recover by itself. There are many factors that can cause edema, so it is recommended that patients consult a doctor in a timely manner to identify the cause of the problem and then carry out the relevant treatment.