Babies usually have redness, swelling and hard nodes within 24 hours after vaccination, which are normal reactions to vaccines and usually related to the type of vaccine and individual differences. It is more common for babies to have local redness, swelling and hard nodes after BCG vaccination. The diameter of redness and swelling is below 2.5 cm for weak reaction; 2.6-5 cm for moderate reaction; and above 5 cm for strong reaction, which may cause local lymph node swelling and pain when strong reaction occurs. It is recommended to apply cold compresses with cool water or fresh potato slices within 72 hours, after 72 hours local hot compresses can be applied to promote the absorption of drugs and the improvement of local inflammation, the symptoms of the milder ones will subside on their own in 2-3 days, the baby should not be given a hot bath, need to feed more water as well as a light diet, and communicate with the doctor in time if there is a fever.