Nitroglycerin is mainly used for the treatment of coronary heart disease and angina pectoris as well as for prevention, and also for lowering blood pressure and treating congestive heart failure. In terms of dosage, you can generally take 1 tablet sublingually during an angina attack, and if the symptoms are not relieved, you can repeat the process after 5 minutes until the pain is relieved. If the pain persists after a total of 3 times in 15 minutes, prompt medical attention is required. Prophylactic application can be done 5-10 minutes before activity or bowel movement to avoid angina attacks. During the application process, adverse reactions may occur, among which the more common is headache, which usually occurs immediately after the drug is administered and can be severe or persistent pain, and will be gradually relieved after stopping the drug. Occasionally, dizziness, weakness, palpitations, and upright hypotension may occur. At therapeutic doses, significant hypotensive reactions may occur, manifesting nausea, vomiting, sweating, fainting, and, more rarely, allergic reactions may occur.