Soreness and weakness of the back of the hand after blood draw is considered to have the following causes: 1. Emotional tension: This can lead to soreness and weakness of the back of the hand after bleeding. 2. Local pain at the needle opening: This stimulates the patient and leads to soreness and weakness of the entire back of the hand. 3. Change in the body’s environment: The flow of a large amount of blood in a short period of time can lead to a change in the body’s internal environment and cause soreness and weakness of the back of the hand. For soreness and weakness in the back of the hand after blood sampling, it is important to relax, especially to properly relax the back of the hand to prevent excessive muscle tension that can cause soreness and weakness in the back of the hand. For the pain caused by the needle opening, most of them can recover in 1-2 days by applying heat.