Most of the vaccinations are given subcutaneously, and the hard bumps that appear after the vaccination are caused by subcutaneous bleeding. In the early stage, you can apply cold towels or ice cubes on the surface or press the injection area with your hand to compress it, which can effectively reduce local bleeding. After one or two days, if you want the hard bumps to be eliminated as soon as possible, you can use hot towels to apply hot compresses, and at the same time, pay attention to the eye of the needle should not be in direct contact with water when applying hot compresses, because there is a possibility of bacterial infection and pain, and the hard bumps can be eliminated after 7-10 days. If there is swelling and abscess formation inside the hard bumps, puncture to draw out the abscess if necessary.