Nitroglycerin mainly refers to nitroglycerin tablets and nitroglycerin injection, the dosage of tablets is usually 0.25-0.5 mg sublingual, can be repeated every 5 minutes, but the maximum amount of no more than 3 tablets. Injections are usually started at 5 μg/min, and the dosage is adjusted according to the condition. Nitroglycerin is mainly used to treat angina pectoris, but can also be used to lower blood pressure or treat congestive heart failure. During angina attacks, 0.25-0.5 mg can be taken sublingually. If the pain is not relieved in 5 minutes, you can take it again. If the symptoms are still not relieved even after taking 3 tablets in a row, it may be myocardial infarction or other diseases, and you need to consult a doctor immediately. Nitroglycerin injection needs to be applied intravenously and the starting dose is 5 micrograms per minute, increasing by 5 μg/min every 3 to 5 minutes, and can be increased in 10 μg/min increments if it is not effective at 20 μg/min. Adjustments need to be made according to the patient’s blood pressure/heart rate and other hemodynamic parameters, under the guidance of medical personnel. Nitroglycerin has the potential to cause hypotension, headache, vertigo, palpitations, syncope, flushing, rash, exfoliative dermatitis and other adverse reactions, for patients with low blood pressure, early myocardial infarction, glaucoma, severe anemia, increased intracranial pressure and other contraindications. The use of nitroglycerin should be carried out under the guidance of a physician or pharmacist to avoid the adverse consequences of self medication.