The most common causes of swollen hands in the morning are as follows: First, localized edema. This is caused by resistance to local venous lymphatic return or increased capillary permeability. For example, phlebitis, or severe local trauma and allergy. Second, drug-related edema. It may occur with the application of insulin or hormonal drugs and certain Chinese medicines. Third, nephrogenic edema. The presence of some impaired kidney function leads to the phenomenon of water and sodium retention due to reduced renal excretion of water and sodium, and the increase of extracellular fluid causes edema. This type of edema is characterized by mild edema of the eyelids, face, and upper limbs in the morning when waking up. The edema gradually develops into a generalized edema. There are often changes in urine, hypertension, and renal impairment. Other conditions such as cardiogenic edema, hepatogenic edema, dystrophic edema, endocrine dysfunction, etc., mostly start from the foot and ankle rather than from the hand. Moreover, these types of edema often do not have the problem of facial as well as upper limb edema. In the case of young people, localized edema is also considered, which may be related to allergies or obstruction of venous lymphatic return. In short, swollen hands in the morning are most likely to have localized edema, which is the most common case of obstructed venous return. Other possibilities to watch out for are drug-related edema and nephrogenic edema.