Lidocaine belongs to the local anesthetic drugs and anti-arrhythmic drugs, in the clinical use of the skin test is not required before, but there is a history of allergy to the drug and other amine local anesthetic drug allergy patients, is prohibited to use. The use of lidocaine for local anesthesia or treatment of cardiac arrhythmia in clinical practice does not require skin testing, because the chances of allergy to the drug are relatively small, and in most cases there is no allergic reaction. Before use need to carefully ask the patient’s allergy history, the existence of the drug and amine local anesthetic drug allergy history can not be used. Some patients in the use of the process may be allergic reactions, such as skin rash, itching and edema, etc., serious cases can occur respiratory and cardiac arrest, etc., need to urgently take the relevant treatment. The above reactions have more to do with the local anesthesia when the drug mistakenly into the blood vessels, so in the use of the need to pump back, avoid injecting into the blood vessels. Lidocaine is contraindicated in the following conditions: As syndrome, severe heart block (Ⅱ or Ⅲ degree atrioventricular block, double bundle branch block), severe sinus node dysfunction and allergic patients. In addition to allergic reactions that can be caused, neurological reactions such as optic neuritis, dizziness and convulsions, and cardiovascular adverse reactions such as sinus bradycardia and ventricular fibrillation can occur. Patients are advised to seek timely medical attention and need to use it under the guidance of a medical professional.