Swelling of the arm after vaccination is mostly due to vaccine irritation, allergy or needle infection. When this phenomenon occurs, different treatments should be taken under the guidance of a doctor according to different situations. Main reasons 1, vaccine stimulation: because the vaccine injected into the body has a certain degree of irritation, if the drug is not completely absorbed, it will easily lead to adverse reactions such as hard nodules, redness or pain at the injection site; 2, vaccine allergy: due to physical reasons, when the patient has an allergic reaction to the vaccine, it will cause arm swelling; 3, needle infection: after the injection of vaccine, do not pay attention to the surrounding skin clean, stained with sewage or When the skin around the vaccine is not cleaned after the injection, and it is contaminated with sewage or sweat, it will easily cause the symptoms of redness and swelling of the arm. If there is bruising at the swollen area, it is considered to be caused by subcutaneous bleeding or tissue fluid exudation, so hot towels can be used to accelerate local blood circulation and eliminate bruising or inflammatory factors as soon as possible; 2. Wipe iodophor for routine disinfection, and if accompanied by itching symptoms, apply glyburide lotion for anti-allergy treatment. The rash, fever and other symptoms should be accompanied by medical examination and treatment. 3, infection leading to arm swelling phenomenon, under the guidance of the doctor in the local application of erythromycin ointment for anti-inflammatory treatment, local inflammation control, arm redness and swelling phenomenon will naturally subside.