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What does it do?

Glyceryl trinitrate ointment is used to treat anal fissures and haemorrhoids. It relaxes the muscles and the blood vessels.

Before you start

  • Tell your doctor if you have a heart problem.
  • Tell your doctor if you have a history of fainting, or sometimes feel lightheaded.
  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you use it?

Insert a 1 to 1.5 cm strip of ointment (see measurement on box) into the rectum, with your finger.
Close the tube tightly, immediately after each use. If the tube is left open, the ointment may not work. Wash your hands after use.

What if you forget a dose?

Apply the missed dose as soon as possible. If it is close to the time for your next dose, skip the missed dose and carry on as normal. Do not apply two doses at the same time.

Can you take other medicines?

Some medicines available without a prescription may react with glyceryl trinitrate including:

  • sildenafil (e.g. Viagra®) or similar medicines. DO NOT use these medicines with glyceryl trinitrate. This can cause severe side effects.

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Fast heartbeat


Tell your doctor

Headache, flushing


Common when treatment begins - if side effects continue or are severe, tell your doctor.

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • Taking alcohol and glyceryl trinitrate at the same time may increase side-effects.

This leaflet contains important, but not all, information about this medicine.

Prepared by the MyMedicines Committee at Christchurch Hospital, Te Whatu Ora - Waitaha, New Zealand. March 2023

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

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About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at Te Whatu Ora – Waitaha. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed