Swollen hands in summer out for a walk may be caused by physiological factors, or may be caused by pathologic factors such as vascular lesions of the upper extremities, allergies, and other diseases. 1. Physiological factors: due to the high temperature in summer, blood vessel expansion, hands are in a low position when walking, the hydrostatic pressure of the capillaries in the hand increases, and local exudate accumulation leads to swelling of the patient’s hands, which can be relieved after resting in general. 2. Upper extremity vascular lesions: common in the upper extremity venous thrombosis, poor blood circulation, caused by blood accumulation in the hands when walking, thus causing hand swelling. 3. Allergy: due to walking, skin contact with pollen and other allergens, patients may appear hand swelling, some patients may be accompanied by itching and other symptoms. 4 other diseases: such as fractures of the upper limbs, vascular nerve injury, cardiovascular disease, kidney disease, can cause patients to go out for a walk in the summer hand swelling. There may be other reasons for summer walking hand swelling, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.