Take this medication by mouth as directed by your doctor, usually once daily when you wake up. Swallow this medication whole with a half glass of water (4 ounces/120 milliliters) unless your doctor directs you otherwise. Do not crush or chew this medication. Doing so can release all of the drug at once, increasing the risk of side effects. Also, do not split the tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing. Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day. Do not stop taking it without consulting your doctor. Some conditions may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased. Although unlikely, when this medication is used for a long time, it may not work as well and may require different dosing. Tell your doctor if this medication stops working well (for example, you have more frequent or worsening chest pain).

Headache, dizziness, lightheadedness, nausea, and flushing may occur as your body adjusts to this medication. If any of these effects persist or worsen, tell your doctor or pharmacist promptly. Headache is often a sign that this medication is working. Your doctor may recommend treating headaches with an over-the-counter pain reliever (such as acetaminophen, aspirin). If headaches continue or become severe, tell your doctor promptly. To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position. An empty tablet shell may appear in your stool. This effect is harmless since your body has already absorbed the medication. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. Tell your doctor right away if you have any serious side effects, including: fainting, fast/irregular/pounding heartbeat. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: drugs to treat erectile dysfunction-ED or pulmonary hypertension (such as sildenafil, tadalafil), riociguat. Some products have ingredients that could worsen your heart failure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products, diet aids, or NSAIDs such as ibuprofen/naproxen). Isosorbide mononitrate is very similar to isosorbide dinitrate. Do not use medications containing isosorbide dinitrate while using isosorbide mononitrate. This medication may interfere with certain laboratory tests (including cholesterol levels), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: slow heartbeat, vision changes, severe nausea/vomiting, sweating, cold/clammy skin, bluish fingers/toes/lips.