There are several common reasons for the swelling of the arm after the rabies vaccination: a. The patient has a more serious allergic reaction to the rabies vaccine, which will be accompanied by obvious swelling, pain and elevated skin temperature in the arm. As soon as possible, the swollen area should be given a topical application of glyburide lotion, oral anti-allergy drugs such as paracetamol and loratadine, and a large amount of water to promote the accelerated metabolism of toxins in the body to reduce the allergic metabolic reaction. Most patients after 24-48 hours of active treatment, the allergic reaction in the body can gradually ease, the swelling of the arm, pain symptoms can subside on their own. Second, if the needle accidentally sticks to the artery, it can cause the formation of local intermuscular hematoma, and cause obvious swelling and pain in the arm, and limb movement is limited. At this time, local pressure can be given to stop the bleeding, if the effect is not good, it is necessary to perform surgery as soon as possible to cut the skin and subcutaneous tissue, to clear the hematoma treatment. Postoperative treatment such as anti-infection, hemostasis and edema reduction can relieve the swelling of the arm more quickly.