Lidocaine is a commonly used local anesthetic in clinical practice, which is relatively safe to apply and generally has few side effects; the more common side effects include central nervous system-related symptoms, cardiovascular symptoms, and skin and subcutaneous tissue injuries. 1. Symptoms related to the central nervous system, such as dizziness, drowsiness, numbness of the mouth and tongue, dizziness, blurred vision, agitation, slurred speech, muscle twitching, in addition to the loss of orientation, a small number of can cause respiratory depression or respiratory arrest. 2. Cardiovascular symptoms, lidocaine overdose can cause myocardial contraction capacity is reduced, blood pressure drop, bradycardia, atrioventricular block and sinus arrest. Therefore, before applying lidocaine injection, it is necessary to master the dosage, to prevent the dosage from being too large, which may cause toxic reactions and ultimately threaten the patient’s life. 3. Skin and subcutaneous tissue injuries, such as blisters, burning sensation of the skin, skin edema and so on. Lidocaine needs to be used under the guidance of a doctor, not blindly used by yourself.