Generic name: isosorbide mononitrate [ EYE-soe-SOR-bide-MON-oh-NYE-trate ]
Brand names: Imdur, Monoket, ISMO
Drug class: Antianginal agents

Medically reviewed by Drugs.com. Last updated on Aug 14, 2023.

What is Imdur?

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

Imdur is an extended release tablet used to prevent angina attacks (chest pain).

Imdur will not treat an angina attack that has already begun.

Warnings

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

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

• congestive heart failure;

• kidney disease; or

• low blood pressure.

It is not known whether Imdur will harm an unborn baby. 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 Imdur?

Take Imdur 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 Imdur tablet. Swallow it whole.

You may have very low blood pressure while taking Imdur. Call your doctor if you are sick with vomiting or diarrhea, or if you are sweating more than usual. Prolonged illness can lead to a serious electrolyte imbalance, making it dangerous for you to use this medicine.

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

You should not stop using Imdur 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 to avoid

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 Imdur (dizziness, drowsiness, feeling light-headed, or fainting).

Imdur side effects

Get emergency medical help if you have signs of an allergic reaction to Imdur: 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.

Imdur 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 Imdur side effects may include:

• headache; 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.

Dosing information

Usual Adult Dose for Angina Pectoris Prophylaxis:

EXTENDED RELEASE:
30 to 60 mg orally once a day in the morning

Maximum dose: 240 mg orally once a day in the morning

Comments:
-Swallow whole (do not crush or chew) with half-glass of fluid.
-Start at low end of dosing range for elderly patients.

Use: Prevention of angina pectoris due to coronary artery disease; onset of action is not sufficiently rapid to be useful in aborting an acute anginal episode.

Usual Adult Dose for Angina Pectoris:

EXTENDED RELEASE:
30 to 60 mg orally once a day in the morning

Maximum dose: 240 mg orally once a day in the morning

Comments:
-Swallow whole (do not crush or chew) with half-glass of fluid.
-Start at low end of dosing range for elderly patients.

Use: Prevention of angina pectoris due to coronary artery disease; onset of action is not sufficiently rapid to be useful in aborting an acute anginal episode.

Related/similar drugs

amlodipine, lisinopril, aspirin, metoprolol, furosemide, carvedilol, spironolactone, atenolol, propranolol, diltiazem

What other drugs will affect Imdur?

Taking Imdur 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:

• avanafil (Stendra);

• a diuretic or "water pill";

• nitroglycerin;

• riociguat (Adempas);

• sildenafil (Viagra, Revatio);

• tadalafil (Cialis, Adcirca); or

• vardenafil (Levitra, Staxyn).

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 Imdur only for the indication prescribed.

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

Medical Disclaimer

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