Lidocaine hydrochloride is a local anesthetic as well as an antiarrhythmic drug. The side effects of lidocaine hydrochloride are dose-related and are generally used for local anesthesia, intrathecal anesthesia, and nerve blocks. When the dose is too high, toxic reactions may occur, such as dizziness, tinnitus, and in severe cases, convulsive states, sinus bradycardia, and other arrhythmic manifestations. The dose and route of administration of lidocaine as a local anesthetic and an antiarrhythmic drug are different. Anti-arrhythmic drugs are usually administered intravenously and require a relatively small dose, while when used as a local anesthetic, the dose is relatively large. If the local anesthetic is pushed into the blood vessels by mistake, toxic reactions may occur. When a more serious toxic reaction occurs, such as a convulsion, it will be controlled with anticonvulsant drugs.