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Isosorbide mononitrate, Isosorbide dinitrate, Glyceryl trinitrate (GTN)

Drug Class: Commonly Known As: Category:
Cardiovascular Agent Adult

Isosorbide mononitrate, Isosorbide dinitrate, Glyceryl trinitrate (GTN) - Side Effects, Precautions, and Contraindications

What side effects can Isosorbide mononitrate, Isosorbide dinitrate, Glyceryl trinitrate (GTN) cause?

  • Headache
  • Flushing or redness of the skin
  • Dizziness
  • Weakness or fainting
  • Rapid heartbeat
  • Nausea and vomiting
  • After taking a dose of this medicine, you may experience temporary headaches. This is a common side effect that will resolve after taking the medicine for a while. You may choose to use painkillers at the start of using nitrates, such as paracetamol, to relieve the temporary headaches. Do consult your doctor should this headache persist or become severe.
  • Dizziness, lightheadedness or faintness may occur, especially when you get up quickly from a lying or sitting down. Getting up slowly or changing postures slowly may help. Do take a rest by sitting or lying down if you feel dizzy.
  • Dizziness, lightheadness or fainting is more likely to occur with concurrent alcohol consumption, long periods of standing, exercise or hot weather. Do be careful to limit the amount of alcohol you drink while you are on nitrates. Extra precaution should also be taken during exercise, hot weather or if it is necessary to stand for long periods of time.

Before taking Isosorbide mononitrate, Isosorbide dinitrate, Glyceryl trinitrate (GTN), what precautions must I follow?


Inform your doctor if you have previously experienced any unusual or allergic reactions to nitrates or nitrites. Do also let your doctor know of any other allergies that you may have, including allergies to certain foods, preservatives or dyes.


Inform your doctor and pharmacist if you are pregnant, plan to become pregnant or are breast- feeding. Do also alert your doctor if you become pregnant while taking nitrates.

Older adults

Elderly are more sensitive to the effects of nitrates, and are more likely to experience dizziness or lightheadedness.

Other medicines

Inform your doctor or pharmacist if you happen to be taking other medications for the control of high blood pressure, heart medications or sildenafil (Viagra®), tadalafil (Cialis®), vardenafil (Levitra®).

What food or medicine must I avoid when I take Isosorbide mononitrate, Isosorbide dinitrate, Glyceryl trinitrate (GTN)?

Do NOT take sildenafil (Viagra®), tadalafil (Cialis®), vardenafil (Levitra®) if you are taking this medicine. When sildenafil, tadalafil or vardenafil is taken with nitrates, blood pressure can lower drastically, resulting in dizziness, lightheadness or fainting. In some cases, death has been reported when sildenafil was taken with nitrates.

  • Updated on Friday, February 1, 2019
  • Article contributed by Department of Pharmacy National Heart Centre Singapore

    The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth


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