Swollen arms after vaccination may be caused by adverse reactions, allergies, infections at the vaccination site, etc., which can be relieved by cold compresses, sterilizing treatments and medications. 1. Adverse reaction: for individual differences, some people may have the adverse reaction of swollen arms after vaccination. Localized cold compresses can be applied to the swollen area to inhibit blood circulation and avoid aggravation of swelling. Adverse reaction symptoms can usually be gradually relieved with time. 2. Allergy: After vaccination, drug stimulation may lead to arm swelling, itching and other allergic symptoms. In this case, you can use loratadine tablets, ebastine tablets and other drugs under the guidance of the doctor to play an anti-allergic role. 3. Bacterial infection: After the vaccination, if you don’t take good care of the eye of the needle, it may lead to bacterial infection, which may cause inflammation of the arm and lead to the symptoms of swollen arm. This situation requires the timely use of povidone-iodine, hydrogen peroxide, etc., to disinfect the local treatment. At the same time, you can use cefaclor capsules, amoxicillin capsules and other antibiotics under the guidance of the doctor to play an antibacterial and anti-inflammatory role. After the vaccine appeared arm swollen situation, it is recommended to go to the hospital in time to do the relevant examination, and under the guidance of professional doctors to carry out the relevant treatment.