The use of anesthetic during tooth extraction does not necessarily cause side effects. If the patient is too nervous, allergic to anesthetic or the doctor does not operate properly, it may lead to the following side effects, but serious side effects are not common: 1. syncope: syncope may be caused by fear, nervousness and fatigue during tooth extraction, which may not be entirely caused by the side effects of anesthetic; 2. anesthetic poisoning: if the amount of local anesthetic is too large and the injection speed is too fast, it may cause an increase in blood pressure, abnormal sensation, muscle tremor, convulsion, slowed heart rate, arrhythmia, cardiac arrest, respiratory depression and other adverse reactions; 3. muscle tremors, convulsions, slowing heart rate, arrhythmia, cardiac arrest, respiratory depression and other adverse reactions; 3, allergic or allergy-like reactions: manifested as erythema, pruritus, rash, angioedema, bronchospasm, dermatitis, respiratory distress, laryngospasm, shock, etc., but the possibility of serious allergic reactions is low; 4, nerve damage: injection needle into the nerve can cause nerve pain, numbness or abnormal sensation Most of these injuries are temporary and reversible, and can generally heal on their own, while a few last for a long time or even cannot return to normal.