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Nitrate medication


Nitrate medicines include glyceryl trinitrate (GTN), isosorbide dinitrate and isosorbide mononitrate. Each has various brand names. Nitrate drugs do not alter the underlying cause of angina. (Angina is usually caused by narrowing of the heart arteries due to a build-up of a fatty substance called atheroma. See the separate leaflet called Angina.) However, nitrate medicines are good at easing and preventing angina pains.

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How do nitrates work?

Nitrates (also known as nitric oxide) work by relaxing the walls of blood vessels, which makes them slightly wider. In angina they work by relaxing the walls of veins that return blood to the heart. This lowers the pressure of that blood and means the heart doesn't have to work as hard. They also make the blood vessels that supply the heart muscle widen a little.

Types of nitrate medicine

Short-acting nitrate preparations

Long-acting nitrate preparations

If you have frequent angina pains, long acting nitrate preparations help to prevent the pains from developing.

A long-acting preparation takes longer to start working, so is not much use for immediate pain relief. But, it works for much longer after each dose than a short-acting preparation (which loses its effect after 20 minutes or so).

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Possible side-effects of nitrates

Common side-effects include:

  • A throbbing headache.

  • A flushed face.

  • You may feel dizzy.

  • Lightheadedness (from the nitrate causing low blood pressure).

  • Feeling slightly nauseous.

  • With the spray under the tongue: a slight burning or tingling sensation under the tongue.

Thankfully these side-effects are unpleasant but not serious. Often they get better once you've been using the medicine for a few weeks.

When should I not take a nitrate medication?

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Are there other medications I shouldn't take if I'm already on a nitrate?

  • Nitrates interfere with some other medicines, which may cause problems. In particular, you should not take sildenafil (Viagra®) or similar medicines used for erectile dysfunction (impotence) if you are taking a nitrate. This is because the combination of the medicines could make your blood pressure go far too low, which can be dangerous.

Will my nitrate medicine stop me having a heart attack?

Although they help with the symptoms of chest pain from the blood vessels getting furred up, they don't change the underlying reason for the chest pains. So although they can make you feel better, they don't prevent heart attacks.

How do I report a side-effect to my medicine?

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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