The precautions of norepinephrine application are mainly about some adverse reactions of the drug, mainly in the following aspects: first, is the leakage of the drug can cause local tissue necrosis; second, is the strong vasoconstriction of this product, which can reduce the blood flow to vital organs, thus leading to the corresponding organ function damage; third, is the reaction that should be paid attention to, including intravenous drip, along the vein into the skin whitening, local skin peeling, purple-dry red skin, and severe vertigo, etc. The consequences are more serious. Individual patients may develop allergy, resulting in rash as well as facial edema. In patients with organic heart disease with hypoxic-electrolyte balance, arrhythmias can occur, and reflex slowing of the heart rate can occur after an increase in blood pressure. Special attention should be paid if agitation, dizziness, headache, pallor, heartbeat, heaviness, insomnia, etc. occur. Hypertension, slow heart rate, vomiting and even convulsions can occur if the dose is overdosed. After long-term intravenous infusion, if suddenly stop the drug can cause a sudden drop in blood pressure, so the drug should be gradually reduced.