After vaccination, swelling and hard nodules at the injection site are usually normal if there is no serious pain or other discomfort, and can usually be relieved by themselves. If the hard nodules are <30mm, they can be treated with hot compresses, and >30mm can be treated with external magnesium sulfate solution. If caused by infection or allergy, it is necessary to seek medical attention and carry out corresponding medication. 1.Hot compress: Patients can apply local hot compress 24 hours after vaccination, which can help promote blood circulation in the hard nodes and play a role in reducing swelling and relieving pain; hot compress is not recommended within 24 hours of vaccination, which may aggravate swelling; if pain occurs, cold compress can be used to relieve pain; 2.Topical medication: magnesium sulfate solution can be used for External application can help relax muscles and promote vasodilation, thus relieving swelling and hard knots; 3. Oral or injectable drugs: If, in addition to swelling and hard knots, symptoms such as abscesses and ulcers occur, accompanied by fever, dizziness, pain and other discomfort, consider the occurrence of infection or allergy. If the condition is caused by infection, antibiotic drugs such as amoxicillin can be applied under the guidance of a professional doctor, and if allergy exists, symptoms can be relieved by using drugs such as dexamethasone and loratadine. In addition, it is normal for some vaccines to have hard nodules after injection, for example, BCG vaccine, small hard nodules will appear locally after 2-3 weeks of injection, which may then turn into small pustules and form permanent scars after the crusts fall off, which is a normal phenomenon.