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Isosorbide Mononitrate

Generic Name: isosorbide mononitrate (EYE soe SOR bide MON oh NYE trate)
Brand Names: Imdur, Monoket, ISMO

Medically reviewed by Kaci Durbin, MD Last updated on Apr 29, 2019.

What is isosorbide mononitrate?

Isosorbide mononitrate is a nitrate that dilates (widens) blood vessels, making it easier for blood to flow through them and easier for the heart to pump.

Isosorbide mononitrate is used to prevent angina attacks (chest pain).

Isosorbide mononitrate will not treat an angina attack that has already begun.

Important information

You should not take erectile dysfunction medicine (Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil, vardenafil) while you are taking isosorbide mononitrate. Taking these medicines together can cause a sudden and serious decrease in blood pressure.

Seek emergency medical attention if you have early symptoms of a heart attack (chest pain or pressure, pain spreading to your jaw or shoulder, sweating, general ill feeling).

Do not stop taking this medicine suddenly. Stopping suddenly could cause a severe angina attack.

Isosorbide mononitrate can cause severe headaches, especially when you first start using it. These headaches may gradually become less severe as you continue to use the medication. Do not stop taking isosorbide mononitrate. Ask your doctor before using any headache pain medication.

Use this medicine regularly to prevent an angina attack. Get your prescription refilled before you run out of medicine completely.

Before taking this medicine

You should not use isosorbide mononitrate if:

  • you are allergic to isosorbide mononitrate, isosorbide dinitrate, or nitroglycerin; or

  • you have early signs of a heart attack (chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating).

You should not take erectile dysfunction medicine (Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil, vardenafil) while you are taking isosorbide mononitrate. Taking these medicines together can cause a sudden and serious decrease in blood pressure.

To make sure this medicine is safe for you, tell your doctor if you have:

  • congestive heart failure;

  • kidney disease; or

  • low blood pressure.

It is not known whether this medicine will harm an unborn baby, although animal studies have not shown harm. Tell your doctor if you are pregnant or plan to become pregnant.

It is not known whether isosorbide mononitrate passes into breast milk or if it could affect the nursing baby. Tell your doctor if you are breast-feeding.

How should I take isosorbide mononitrate?

Take isosorbide mononitrate exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose. Do not take this medicine in larger or smaller amounts or for longer than recommended. If you use too much isosorbide mononitrate, it might stop working as well in controlling your condition.

Try to rest or stay seated when you take this medicine (may cause dizziness or fainting).

Do not crush, chew, or break an extended-release tablet. Swallow it whole.

Not all brands and forms of isosorbide mononitrate are taken the same number of times per day. You may need to take the medicine only once daily, in the morning after getting out of bed. You may also need a second dose later in the day.

Follow your doctor's dosing instructions very carefully. If your doctor changes your brand, strength, or type of isosorbide mononitrate, your dosage needs may change. Ask your pharmacist if you have any questions about the new brand of medicine you receive at the pharmacy.

Use this medicine regularly to prevent an angina attack. Get your prescription refilled before you run out of medicine completely.

You should not stop using isosorbide mononitrate suddenly or you could have a severe attack of angina. Keep this medicine on hand at all times. Get your prescription refilled before you run out of medicine completely.

Store at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of isosorbide mononitrate can be fatal.

Overdose symptoms may include a severe throbbing headache, fever, confusion, severe dizziness, fast or pounding heartbeats, vision problems, nausea, vomiting, stomach pain, bloody diarrhea, trouble breathing, sweating, cold or clammy skin, fainting, and seizure (convulsions).

What should I avoid while taking isosorbide mononitrate?

This medicine may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert. Avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.

Avoid drinking alcohol. Alcohol may increase certain side effects of isosorbide mononitrate (dizziness, drowsiness, feeling light-headed, or fainting).

Isosorbide mononitrate side effects

Get emergency medical help if you have signs of an allergic reaction to isosorbide mononitrate: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • a light-headed feeling, like you might pass out;

  • worsening angina pain;

  • fast or slow heart rate; or

  • pounding heartbeats or fluttering in your chest.

Isosorbide mononitrate can cause severe headaches. These headaches may gradually become less severe as you continue to use nitroglycerin. Do not stop taking this medicine to avoid headaches. Ask your doctor before using any headache pain medication.

Common isosorbide mononitrate side effects may include:

  • headache;

  • dizziness upon standing; or

  • flushing (warmth, redness, or tingly feeling).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect isosorbide mononitrate?

Taking isosorbide mononitrate with certain other medicines can cause severely low blood pressure. This includes medicine to treat erectile dysfunction or pulmonary arterial hypertension. Serious, life-threatening side effects may occur.

Tell your doctor about all your current medicines and any you start or stop using, especially:

  • erectile dysfunction medication (including Viagra, Cialis, Levitra, Stendra, Staxyn, sildenafil, avanafil, tadalafil, vardenafil, others);

  • a diuretic or "water pill";

  • blood pressure medications including calcium channel blockers (such as nifedipine, Procardia);

  • nitroglycerin; or

  • riociguat (Adempas);

This list is not complete. Other drugs may interact with isosorbide mononitrate, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use isosorbide mononitrate only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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