A little swelling under the eyes may be due to physiological factors, eye diseases and systemic diseases. 1. Physiological factors, due to the looseness of the tissues around the eyes, when you drink too much water before going to bed, it is easy to lead to edema of the skin under the eyes; in addition, when the age gradually grows up, the skin fat around the eyes will gradually lose, and it is more likely to accumulate fluids, resulting in swelling under the eyes. 2. Eye diseases, such as blepharoplasty, blepharitis caused by Staphylococcus aureus infection, and allergies around the eyes, can also cause swelling under the eyes. 3. Systemic diseases, when suffering from liver and kidney diseases that affect the function of the liver and kidney, the metabolism of the whole body will be disturbed, resulting in swelling of the body, and the thin skin around the eyes is more prone to swelling. If the swelling under the eyes is not relieved or even aggravated by rest, it is recommended to consult a doctor in time.