Facial edema may be caused by drinking too much water, or it may be caused by kidney disease, cardiac insufficiency, allergy and so on. 1. Drinking too much water: If you drink too much water, it will cause facial edema, especially if you drink too much water at night, the facial swelling will be more obvious in the morning of the next day. 2. Kidney diseases: such as common nephritis, nephrotic syndrome, etc., due to disease-induced renal insufficiency, resulting in sodium retention, causing edema around the body. 3. Cardiac insufficiency: patients with cardiac insufficiency mainly show edema of lower limbs and face. It is mainly caused by the obstruction of venous return of the heart, resulting in elevated venous pressure. 4. Allergy: When contacting substances that cause body allergy, patients will have itching and redness, and in severe cases, there will be redness and swelling, and even anaphylactic shock. It is recommended that the patient seek medical attention in time, carry out the appropriate examination to clarify the cause, and take appropriate measures under the guidance of the doctor.