Nitroglycerin and isosorbide nitrate are both drugs used in the treatment of angina pectoris, but they have different onset of action, duration of action and side effects. 1. Onset of action and duration of action: nitroglycerin is usually taken under the tongue, but there are also spraying agents, 2 to 3 minutes or so onset of action, the effect lasts about 30 to 40 minutes. Isosorbide nitrate oral drug effect lasts longer, about 4 to 6 hours, and common sublingual tablets, about 2 to 5 minutes onset of action, the effect lasts 1 to 2 hours. 2. Side effects: nitroglycerin can reduce myocardial oxygen consumption, can quickly relieve angina pectoris caused by coronary artery disease, but the side effects of the drug is larger, after taking it, there will be a more intense persistent headache, there will be nausea, vomiting, and so on. Isosorbide nitrate can also be used to relieve angina, with a slow onset of action, but with fewer side effects, such as dizziness and nausea. Both drugs should be used under medical supervision.