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Overview: Isosorbide mononitrate is a tablet taken to prevent chest pain from heart disease. It works by relaxing the blood vessels that deliver oxygen to the heart. Common side effects include headache and dizziness. Serious side effects are rare, but can include low blood pressure. Notify your healthcare provider right away if you have confusion or feel unusually weak or tired.

Uses

What is isosorbide mononitrate used for?

Isosorbide mononitrate is commonly taken to prevent chest pain caused by heart disease.

Isosorbide mononitrate may also be taken for other conditions as determined by your healthcare provider.

How does isosorbide mononitrate work (mechanism of action)?

Isosorbide mononitrate helps your blood vessels relax so that blood can move through them more easily and bring oxygen to your heart. This helps prevent chest pain from happening.

How is isosorbide mononitrate supplied (dosage forms)?

Brand and other names 

  • Monoket

Dosage forms and strengths

  • 10 mg, 20 mg oral tablets
  • 30 mg, 60 mg, 120 mg extended-release oral tablets

How should I store isosorbide mononitrate?

Isosorbide mononitrate should be stored at room temperature, around 77 F (25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store tightly closed in a cool, dry place.

Side Effects

What are the most common side effects of isosorbide mononitrate?

The most common side effects of isosorbide mononitrate are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Headache
  • Dizziness

There may be other side effects of isosorbide mononitrate that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of isosorbide mononitrate?

While less common, the most serious side effects of isosorbide mononitrate are described below, along with what to do if they happen.

Low Blood Pressure (Hypotension). Isosorbide mononitrate may cause low blood pressure. Low blood pressure is more likely to occur if you have excessive sweating or persistent or severe vomiting or diarrhea. If you feel faint or dizzy, lie down. Tell your healthcare provider right away if you have any of the following symptoms of low blood pressure.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired

Chest Pain. While isosorbide mononitrate is commonly taken to prevent chest pain, it may cause chest pain in certain people, which can be a symptom of a heart attack. The risk of chest pain is increased in people with existing heart disease. Do not take isosorbide mononitrate if you have had a recent heart attack without talking to your healthcare provider. Get emergency help if you have any of the following symptoms of a heart attack.

  • Chest pain or pressure
  • Fast or abnormal heartbeat
  • Trouble breathing
  • Pain in your back, jaw, throat, or arm
  • Sweating, upset stomach, vomiting, or dizziness

Severe Allergic Reactions. Isosorbide mononitrate may cause allergic reactions, which can be serious. Stop taking isosorbide mononitrate and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use isosorbide mononitrate?

Allergies to Ingredients. People who are allergic to any of the following should not take isosorbide mononitrate.

  • Imdur
  • Ismo
  • Monoket
  • Isosorbide mononitrate
  • Any other medicine known as a nitrate
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific isosorbide mononitrate products they stock.

Drug Interactions. Isosorbide mononitrate should not be taken while you are using certain other medicines. Before taking isosorbide mononitrate, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

What should I know about isosorbide mononitrate before using it?

Do not take isosorbide mononitrate unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share isosorbide mononitrate with other people, even if they have the same condition as you. It may harm them.

Keep isosorbide mononitrate out of the reach of children.

Isosorbide mononitrate should be taken regularly, on a specific schedule, to prevent chest pain. It does not start working quickly enough to be taken to treat acute episodes of chest pain. Get help right away if you develop chest pain.

Do not chew or crush isosorbide mononitrate extended-release tablets. They should be swallowed whole. Some of the isosorbide extended-release tablets can be broken, but not all of them. Check with your pharmacist if you have questions or concerns.

When taking isosorbide mononitrate, you may feel lightheaded when standing up, especially after getting up from lying down or sitting. Be sure to rise slowly to avoid dizziness.

Isosorbide mononitrate can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how isosorbide mononitrate affects you.

People who are 65 or older can be at greater risk for some side effects from isosorbide mononitrate. Talk to your healthcare provider about your risks if you are in this age group.

Headaches are a common side effect with isosorbide mononitrate. Headaches often go away over time. If headaches continue, do not adjust your dose or stop taking isosorbide mononitrate. Ask your healthcare provider about how to handle this. 

What should I tell my healthcare provider before using isosorbide mononitrate?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if isosorbide mononitrate is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Heart problems, including heart failure and hypertrophic cardiomyopathy
  • Low blood pressure
  • Recent heart attack
  • At risk for dehydration, such as with persistent or severe vomiting or diarrhea

Pregnancy. It is not known if or how isosorbide mononitrate could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant.

Breastfeeding. It is not known if isosorbide mononitrate passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take isosorbide mononitrate while breastfeeding.

Interactions

Does isosorbide mononitrate interact with foods or drinks?

There are no known interactions between isosorbide mononitrate and foods or drinks.

The risk of dizziness and low blood pressure may be increased if you drink alcohol while taking isosorbide mononitrate.

Does isosorbide mononitrate interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking isosorbide mononitrate.

  • A phosphodiesterase-5 (PDE-5) inhibitor, such as avanafil (Stendra), sildenafil (Viagra, Revatio, and others), tadalafil (Cialis and others), or vardenafil (Levitra, Staxyn), which is a medicine used for erectile dysfunction or pulmonary arterial hypertension (PAH)
  • Riociguat (Adempas), which is a medicine used for pulmonary arterial hypertension (PAH)
  • A medicine for high blood pressure

This may not be a complete list of medicines that can interact with isosorbide mononitrate. Always check with your healthcare provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much isosorbide mononitrate?

If you or someone else has used too much isosorbide mononitrate, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of isosorbide mononitrate?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.