The hepatitis B vaccine is a recombinant gene vaccine and generally does not have many side effects. A small number of people will have hard nodules under the skin after the injection of the late vaccine, mainly due to local drug stimulation. Generally, no special treatment is needed, and it is necessary to avoid water and local extrusion. With the extension of time, it can generally subside on its own, but if it does not subside even after a week, or even if local pus or infection occurs, it is necessary to go to the hospital for local treatment. If the redness and swelling are only slight, hot towels can be used to promote the absorption of hard nodules, and Xylitol can be applied locally.