ISOSORBIDE-5-MONONITRATE 25 MG


What is isosorbide mononitrate?

Isosorbide mononitrate is in a group of drugs called nitrates. It 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.

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Important information

Do not use isosorbide mononitrate if you are taking medicine to treat erectile dysfunction or pulmonary arterial hypertension (PAH). This includes sildenafil (Viagra, Revatio), avanafil (Stendra), tadalafil (Cialis, Adcirca), vardenafil (Levitra, Staxyn), and riociguat (Adempas). Serious, life-threatening side effects may occur.

You should not use isosorbide mononitrate if you have early signs of a heart attack (chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling).

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

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.

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

Before taking this medicine

Do not use isosorbide mononitrate if you are taking medicine to treat erectile dysfunction or pulmonary arterial hypertension (PAH). This includes sildenafil (Viagra, Revatio), avanafil (Stendra), tadalafil (Cialis, Adcirca), vardenafil (Levitra, Staxyn), and riociguat (Adempas). Serious, life-threatening side effects may occur.

You should not use this medicine 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).
To make sure this medicine is safe for you, tell your doctor if you have:

congestive heart failure;
low blood pressure; or
kidney disease (or if you are on dialysis);
if you take a diuretic or "water pill"; or
if you are on a low salt diet.
FDA pregnancy category C. It is not known whether isosorbide mononitrate will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

See also: Pregnancy and breastfeeding warnings (in more detail)

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

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 to make sure you get the best results. Do not take this medicine in larger or smaller amounts or for longer than recommended.

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. Or you may need a second dose later in the day. Follow your doctor's dosing instructions very carefully.

If possible, try to rest or stay seated when you use this medicine. Isosorbide mononitrate can cause dizziness or fainting.

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

You may have very low blood pressure while taking this medicine. 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 isosorbide mononitrate.

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

You should not stop using this medicine suddenly if you take this medicine to prevent angina. Stopping suddenly may cause you to have a severe attack of angina.

Do not change brands of isosorbide mononitrate without the approval of your doctor.

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 should I avoid while taking isosorbide mononitrate?

This medication 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.

Drinking alcohol can increase certain side effects of isosorbide mononitrate.

Isosorbide mononitrate side effects

Get emergency medical help if you have any of these 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, especially when you first start using it. These headaches may gradually become less severe as you continue to use this medicine. 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; 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.


Isosorbide mononitrate dosing information

Usual Adult Dose for Angina Pectoris Prophylaxis:

30-60 mg (Imdur) orally once a day or
20 mg (ISMO) orally twice a day or
10-20 mg (Monoket) orally twice a day.

Usual Adult Dose for Congestive Heart Failure:

30-60 mg (Imdur) orally once a day or
20 mg (ISMO) orally twice a day or
10-20 mg (Monoket) orally twice a day.

What other drugs will affect isosorbide mononitrate?

Other drugs may interact with isosorbide mononitrate, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.