There are many reasons for the numbness of the back of the hand, such as trauma, skin infections, allergies, mosquito bites, and abnormal neuromodulation. 1. Trauma: for example, by the outside world of extrusion, bruises, friction, physical stimulation, or frostbite and other reasons, may cause the back of the hand numbness. 2. Skin infections: for example, bacterial, viral, fungal and other pathogenic bacteria, resulting in skin and hair follicle infections, can also cause the back of the hands numbness. 3. Allergy: contact dermatitis, urticaria and other allergic diseases, may also lead to tingling on the back of the hand. 4. Mosquito bites: mosquito bites may cause congestion and swelling of the skin on the back of the hand, which may also lead to numbness on the back of the hand. 5. abnormal nerve regulation: such as peripheral neuritis, diabetes-induced neuropathy and shingles, resulting in nerve damage, may lead to the back of the hand numbness. The back of the hand numbness, there may be other reasons need to go to the hospital in time to check, follow the doctor’s instructions for treatment.