Tetanus injection is also known as tetanus antitoxin injection, and tetanus antitoxin injection is usually associated with gastrointestinal adverse reactions or the development of allergic reactions. In case of fasting, the injection may cause gastrointestinal adverse reactions or aggravate the original adverse reactions, such as abdominal distension, abdominal pain, nausea or even vomiting. If allergic symptoms occur, because the blood sugar level in the body is much lower than normal when fasting, it can easily lead to the aggravation of systemic symptoms, and in serious cases, allergic reactions can occur, inducing anaphylaxis and life-threatening, so it is recommended to eat before injecting tetanus antitoxin.