Sudden swelling of the hand can be caused by a variety of reasons such as hand trauma, allergies, infection, compression and so on. 1. Trauma: trauma leads to soft tissue contusion of the hand or hand fracture, joint dislocation, etc., can appear in the hand of sudden swelling, and can be accompanied by pain. Restriction of activities and other manifestations. 2. Allergy: when exposed to allergens, can also induce swelling of the hand, and can be accompanied by itching, redness and other symptoms, should be removed from the allergen as soon as possible. 3. Infection: Bacterial infection in the deep interspace of the palm, acute septic tenosynovitis, septic bursitis and other bacterial infections of the hand can occur in the palm of the hand, the fingers of the swelling, pain and even ischemic necrosis and other serious symptoms. 4. Compression: prolonged pressure on the hands can cause blood circulation disorders and swelling of the hands, which can be relieved when the blood circulation is normalized. If hand swelling persists, it is recommended to consult a doctor as soon as possible for a clear diagnosis.