There are many adverse reactions to BCG vaccination, which vary from person to person, and may include allergic reactions, enlarged lymph nodes, osteomyelitis, and so on. 1. Allergic reaction: such as allergic rash, anaphylactic shock, and allergic cyanosis, etc. Patients will have fever, skin rash, itching and other symptoms, which will seriously affect breathing and easily lead to hypoxia. 2. Enlarged lymph nodes: BCG vaccination may cause lymphadenitis, which leads to enlarged lymph nodes and lymph node pain. 3. Osteomyelitis: Failure to take proper care of local cleaning after BCG vaccination may cause local bacterial infection, which may easily lead to osteomyelitis, resulting in destruction of bone marrow. The lesion may be red, swollen and painful, and there will be obvious pressure and pain. BCG vaccination should know that if there are symptoms such as body fever, nausea, vomiting, diarrhea, etc., it should not be inoculated, and only after the body has fully recovered to normal, so as not to aggravate the discomfort. If you need BCG vaccination, you should consult your doctor first to understand your personal situation, and in the case that you cannot be vaccinated, you need to postpone the vaccination.