The combined diphtheria and tetanus vaccine is used to prevent pertussis, diphtheria and tetanus. This vaccine is one of the vaccines in the national immunization program, and the vaccination target is children aged 3-24 months. The incidence of adverse reactions to vaccination is the highest of all vaccines. Common adverse reactions include redness, swelling, pain and itching at the injection site, and systemic reactions may include low fever, which generally does not require special treatment if it does not exceed 38°C. The body temperature will decrease with plenty of water. Rare adverse reactions include irritability, anorexia, vomiting, mental discomfort, etc. Severe febrile reactions or persistent fever should be given symptomatic treatment with drugs and prompt medical consultation to prevent hyperthermia. After the first injection of high fever, convulsions and other abnormalities, no longer inject the second injection, after the injection may have local hard nodules, 1-2 months to absorb. When the second injection is given, the site should be changed to the other side, and in serious cases, it may be accompanied by lymphatic vessels or lymph nodes inflammation, and prompt medical consultation should be sought.