Try to drink water after 30 minutes after taking nitroglycerin. Nitroglycerin is not suitable to be taken orally because it is affected by the first-pass effect and its bioavailability is only 8%, so it is mostly taken sublingually. Because of the high fat solubility, it is very easy to be absorbed through the oral mucosa by sublingual intake, and it can be effective in 1~2 minutes after intake, and the efficacy lasts for 20~30 minutes, and the elimination half-life is 2~4 minutes. Therefore, after taking nitroglycerin under the tongue, try to drink water after 30 minutes to avoid affecting the absorption of nitroglycerin, thus affecting the effect of the drug. Nitroglycerin is mostly used in the clinic for the rapid relief of all kinds of angina pectoris and myocardial infarction. It is also used to diastole pulmonary blood vessels, improve pulmonary ventilation, for acute respiratory failure and pulmonary hypertension. Adverse reactions include temporary flushing of the skin of the cheeks, throbbing headache, upright hypotension and syncope. Hypersensitivity to the drug, shock, low systolic blood pressure, postural hypotension, etc., lactation and pregnancy need to be prohibited. The above drugs need to be used under the supervision of a physician, do not use drugs without authorization.