Nitroglycerin should be taken sublingually when angina occurs due to coronary artery disease. Nitroglycerin belongs to the nitrate class of drugs and is mainly used for the prevention and rapid relief of angina attacks due to coronary artery disease. It is taken sublingually when angina attacks, or when angina precursors such as chest pressure appear. If angina attacks are frequent, it can be used prophylactically 5~10 minutes before activities or bowel movements to avoid angina induced by exertion or force. It should be noted that it should be prohibited for those who are allergic to nitrates, early stage of myocardial infarction (with severe hypotension and tachycardia), severe anemia, glaucoma, and increased intracranial pressure. It is also contraindicated in people taking sildenafil citrate because sildenafil citrate can enhance the hypotensive effect of nitroglycerin. Adverse reactions such as headache, dizziness, vomiting, flushing, hypotension, drowsiness, rapid heartbeat, and fatigue can occur with the use of this product. Therefore, this product should be used under the supervision of a doctor and should not be taken on its own to avoid adverse consequences.