Glyceryl trinitrate (Rectogesic)

How does it work?

Rectogesic rectal ointment contains the active ingredient glyceryl trinitrate, which is a type of medicine called a nitrate. It is used to relieve pain associated with anal fissures.

An anal fissure is a tear in the lining of the back passage (anus). It is often caused by passing hard stools when you are constipated. The tear is painful and often bleeds when you pass a stool.

The tear may also be caused in part by spasm (tightening) of the muscle around the anus (the internal sphincter). Spasm of this muscle also causes pain, because if the muscle around the anus is tight, the blood supply to the anus is reduced. This can also slow down the healing process.

The main treatment for anal fissures involves trying to prevent constipation, because straining to pass the stool and passing large hard stools cause more problems. The tear often heals by itself in a couple of weeks, but may sometimes be ongoing. This is called a chronic anal fissure. Glyceryl trinitrate ointment is used to relieve the pain of a chronic anal fissure and also helps the tear heal.

The ointment is applied inside the anus. It works by releasing a chemical called nitric oxide, which is a chemical also made naturally by the body. Nitric oxide relaxes (dilates) blood vessels. It also relaxes the internal sphincter muscle in the anus. This improves the blood supply to the anus, which relieves the pain and helps the fissure to heal.

You should keep using the ointment for as long as your doctor has prescribed it; this will usually be until the pain has got better (up to a maximum of eight weeks).

What is it used for?

  • Pain due to a tear in the lining of the anus (chronic anal fissure).


  • This medicine is not to be taken by mouth.
  • Wash your hands after applying the ointment.
  • Although this medicine acts locally when applied to the anus, it is also absorbed into the bloodstream and can therefore have effects on the rest of the body. In particular, it can cause headaches. It may also cause a drop in blood pressure, especially when you move from a lying or sitting position to sitting or standing. The drop in blood pressure can make you feel dizzy or unsteady. To avoid this try changing position slowly. If you do feel dizzy, sit or lie down until the symptoms pass. If affected you should avoid performing potentially hazardous tasks such as driving or operating machinary. Drinking alcohol is likely to enhance any dizziness.

Use with caution in

  • Severe liver disease.
  • Severe kidney disease.
  • Angina.
  • Heart failure.
  • People who have recently had a heart attack.

Not to be used in

  • Children aged under 18 years.
  • Allergy to nitrates.
  • Low blood pressure (hypotension).
  • A drop in blood pressure that occurs when going from lying or sitting to sitting or standing, causing dizziness (postural hypotension).
  • Low volume of circulating blood (hypovolaemia), for example due to dehydration or blood loss.
  • Head injury.
  • Bleeding in the brain (cerebral haemorrhage).
  • Poor blood flow to the brain.
  • Migraine.
  • Recurrent headache.
  • Narrowing of the main artery coming from the heart (aortic stenosis).
  • Narrowing of one of the valves in the heart (mitral valve stenosis).
  • Heart disease in which the muscle of the heart grows abnormally (hypertrophic obstructive cardiomyopathy).
  • Inflammation of the sac surrounding the heart, which stops the heart from beating properly (constrictive pericarditis).
  • Fluid in the sac surrounding the heart, which prevents the heart beating properly (pericardial tamponade).
  • Severe anaemia.
  • Closed angle glaucoma.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.

If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • The safety of this medicine in pregnancy has not been established. It should not be used during pregnancy, particularly in the first trimester, unless considered essential by your doctor. Seek medical advice from your doctor.
  • It is not known if glyceryl trinitrate passes into breast milk. For this reason this medicine should be used with caution by women who are breastfeeding. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

  • Headache.
  • Dizziness.
  • Nausea and vomiting.
  • Rectal bleeding.
  • Pain.
  • Anal burning or itching.
  • Increased heart rate.
  • Blurred vision.
  • Tiredness.
  • Allergic skin reactions.
  • Low blood pressure.
  • Fainting.
  • Worsening of angina chest pain.

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.

For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

You should not take any of the following while you are using Rectogesic, as the combination could produce a significant drop in blood pressure, resulting in dizziness, fainting, or even a heart attack:

  • sildenafil (Viagra)
  • tadalafil (Cialis)
  • vardenafil (Levitra)
  • glyceryl trinitrate (GTN) for angina or heart failure
  • isosorbide mononitrate
  • isosorbide dinitrate
  • amyl nitrate (also known as poppers).

As Rectogesic can cause a drop in blood pressure, this effect may be also be enhanced if Rectogesic is used by people who are taking other medicines that lower blood pressure. These combinations could cause dizziness. Other medicines that lower blood pressure include the following:

  • medicines to treat high blood pressure (antihypertensives), eg beta-blockers, ACE inhibitors, alpha-blockers, diuretics, calcium-channel blockers
  • tricyclic antidepressants, eg amitriptyline
  • MAOI antidepressants, eg phenelzine
  • certain antipsychotic medicines
  • alcohol.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain glyceryl trinitrate for treating anal fissure.