Using Glyceryl Trinitrate (GTN) tablets to treat chest pain

Patient Leaflets Team

  • Reference Number: HEY1233/2021
  • Departments: Cardiology, Pharmacy


This leaflet has been produced to give you general information. Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and the healthcare team, but may act as a starting point for discussion. If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team.

What are GTN tablets and how do they work?

GTN is medication used to relieve angina (chest pain). When a GTN tablet is placed under the tongue, it relaxes and widens blood vessels, which increases blood flow to the heart. 

How do I use the GTN tablets?

You should carry your GTN tablets with you at all times and do not hesitate to use it if you develop chest pain or discomfort. Place one tablet under your tongue and follow the instructions overleaf.

Are there any side effects?

GTN widens the blood vessels that go to the brain, commonly causing headaches. Although unpleasant, this is not anything to worry about and can be relieved by taking paracetamol. People who suffer from headaches can remove the tablet as soon as their chest pain is relieved to prevent a headache from occurring. GTN can also cause a drop in your blood pressure, so use the tablets while sitting down to avoid the risk of dizziness and fainting.

These side effects happen more often with the first few doses and are likely to become less of a problem over time. If these side effects continue to be a problem, please speak to your doctor. 

Is there anything else I need to know?

You should continue to carry around your GTN tablets with you unless otherwise instructed by your doctor. Always read the leaflet that comes with your GTN tablets and see your doctor or pharmacist if you have any questions or concerns. Alternatively, you can contact your cardiac rehabilitation team (your team is the area in which your doctor is located):

  • Hull                                            (01482) 335466
  • East Riding                                (01482) 335457
  • Scarborough, Whitby, Ryedale  (01723) 380582
  • North Lincs                                (01724) 290093
  • York                                           (01904) 725821
  • Louth                                         (01507) 605826
  • Lincoln                                       (01522) 340900

Regularly check the expiry date of your GTN tablets, and ensure you get a new prescription from your doctor before this has passed. GTN tablets expire 8 weeks after opening, so write the date of opening on the tablet bottle.

Please report to your doctor if you have an increase in your chest pain symptoms (e.g. if you are using your GTN tablets more than three times a week) or if they start to occur at rest.

GTN is also useful for preventing “predictable” angina symptoms. This means you can use it before undertaking an activity you know will bring on your angina. You should only use it this way if advised by your doctor.

How to use your GTN tablets

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