Children’s vaccination arm swelling, may be an adverse reaction to vaccination, may also be local infection inflammation, allergies and other factors, can be taken according to the cause of the general treatment, drug treatment. 1. Adverse reaction to vaccination: under normal circumstances, there may be slight swelling on the day of vaccination, which is a normal reaction, adverse reaction to vaccination, the day of vaccination can be appropriate ice packs, the second to third days or so can be appropriate hot compresses, can promote absorption. 2. Local infection and inflammation: If the inflammation is caused by local infection and inflammation after vaccination, you can apply erythromycin ointment and mupirocin ointment externally. 3. Allergy: If the local redness, swelling and hard nodules are caused by allergy, it is recommended to take oral loratadine and cetirizine for anti-allergy treatment; if the local reaction is more obvious, hydrocortisone butyrate ointment and budesonide ointment can be applied externally. Children need to be observed for a period of time after vaccination, if the adverse reaction is more obvious, or cause systemic discomfort, should immediately consult a doctor, under the guidance of the doctor standardized treatment.