Localized lumps after vaccination are a relatively common occurrence, usually caused by skin irritation from the vaccine medication or by pushing the needle too fast during the injection. There is usually no need to worry too much about it, as it usually subsides gradually in about 24-48 hours, but in a few cases it may take longer than 48 hours. It is important to note that you should not take a shower on the day of vaccination to prevent local infection or septicemia. If the size of the lump is relatively large, you can use potato slices to put on the local area at the early stage of swelling, or you can use hot towels for local hot compresses, which can usually be effectively relieved, and you must drink more water during the vaccination period to accelerate the metabolism of the body.