Gastrografin preparation for your CT colonography examination
What is Gastrografin and why do I need to take it?
Your doctor has arranged for you to have a CT colonography examination, which is a CT scan of the large bowel. In order to see the inside of your bowel clearly, we ask you to drink a special liquid called Gastrografin. It makes the CT pictures of your bowel clearer, by emptying your bowel and highlighting any leftover faecal residue (poo).
Gastrografin is a contrast medium (a dye) which contains iodine. Please contact the CT scan department if you are allergic to iodine or have difficulty swallowing liquids.
What Gastrografin contains:
The active substances are sodium amidotrizoate and meglumine amidotrizoate. 1 ml of solution contains 100 mg sodium amidotrizoate and 660 mg meglumine amidotrizoate. The other ingredients are disodium edetate, sodium hydroxide, saccharin sodium, star anise oil, polysorbate 80, and purified water.
How you will be given Gastrografin?
Drink half of the bottle of Gastrografin (50 mls) mixed with an equal amount of water at 5pm two days before the examination and another 50 mls of Gastrografin mixed with an equal amount of water at 5pm the day before the examination. You may add cordial to the water.
If you receive more Gastrografin than you should, please be aware that ‘overdosing’ is unlikely. If it does happen the radiologist will treat any symptoms that follow. If you have any further questions on the use of this medicine, ask your doctor or the X-ray department staff/radiologist for advice before receiving this medicine.
What you need to know before you are given Gastrografin
Please read the main information leaflet from the manufacturers (Bayer) before taking Gastrografin. This will be given to you once you have received the Gastrografin medicine.
You must not use Gastrografin if you have any of the following:
- If you are allergic to sodium amidotrizoate, meglumine amidotrizoate, iodine or iodine containing contrast media or any of the other ingredients of this medicine
- If you have a condition caused by too much thyroid hormone (manifest hyperthyroidism).
- Graves' Disease.
- If you are pregnant or breastfeeding.
Warning and precautions to take:
- Talk to your doctor or the X-ray department staff/radiologist before receiving Gastrografin. You must tell the X-ray department staff if you have any of the following:
- Any type of thyroid disease (e.g. hyperthyroidism). Your thyroid function may be tested before receiving Gastrografin and you may be given thyreostatic medication (medication to reduce thyroid gland function).
- A history of allergy or a tendency to develop hypersensitivity reactions (for example if you have hay fever, asthma or eczema).
- Heart or blood circulation problems, because in the rare event that you have an allergic reaction, it is more likely to be serious or fatal.
Gastrografin with food and drink
Before the examination the X-ray department staff should make sure that you have had enough to drink and eat before you start the diet sheet and that any imbalances in your body water and body salts are corrected.
Can I take any other medications along with Gastrografin?
Unless you are taking any of the medication mentioned below, you should continue to take your regular medicines as prescribed by your doctor unless you are advised otherwise by this leaflet, a medical professional, or a member of the CT Team. This includes all diabetic medications.
Iron tablets: Please stop taking iron tablets 4 days before your scan.
Interleukin-2: If you are taking Interleukin-2: or have done within the last several weeks, then please telephone the Radiology department and let us know the last date you took this medicine, as there is a higher chance of getting delayed reactions (e.g. fever flu-like symptoms, joint pain and pruritus (itching).
Beta-blockers: If you are taking beta-blockers please telephone the Radiology department and let us know the last date you took this medicine. Please be aware that taking beta-blockers can aggravate any hypersensitivity or allergic type reaction. If you are concerned you may be experiencing any allergic reactions please contact your GP or emergency department for advice.
Metformin: If you are diabetic on metformin, please inform a member of the CT Team who will check you have recent blood results and advise if you need to stop taking metformin.
Insulin: Continue taking your insulin throughout the preparation for this test. On day two of the diet you should reduce your insulin dose by half unless otherwise instructed by your GP. Please closely monitor your blood sugars throughout the preparation leading up to your appointment.
Does Gastrografin have any side effects?
All drugs may have some side effects. Most people who receive Gastrografin experience few side effects.
Gastrografin has a desired laxative effect and may cause diarrhoea so it is advisable to stay close to a toilet.
It is important to take note of any new symptoms you experience after starting the preparation. If you are concerned please telephone the number on your appointment letter to speak to a member of the CT team.
If you notice any of the below, tell the radiologist or X-ray staff immediately as these may be the first signs of allergic reaction or shock:
- Itching of the skin, rash, wheals on the skin (urticaria)
- difficulty breathing, gagging, feeling of suffocation
- swelling of the face, neck or body
- itchy or watery eyes, tickling in the throat or nose, hoarseness, coughing or sneezing
- headache, dizziness, feeling faint
- feeling particularly hot or cold, sweating
- paleness or reddening of the skin
- chest pain, cramp, tremor
- feeling sick
If you currently have inflammation of the intestine or bowel (enteritis or colitis), this may temporarily get worse. If you currently have a blockage in your bowel, this can lead to Gastrografin staying in the bowel for longer than usual which may damage the lining of the bowel.
Delayed reactions can occur. If you are concerned you should contact your doctor.
Other than the symptoms listed above, the other side effects that you might experience are:
- feeling sick or being sick
- anaphylactic shock (a very severe allergic reaction)
- allergic-type skin reactions including itching, redness, wheals on the skin
- disorder of your body water and body salts balance
- fainting, dizziness, headache
- fast heartbeat, sudden stopping of the heart (cardiac arrest), low blood pressure, shock
- difficulty breathing, swelling or fluid in the lungs. If Gastrografin gets into your lungs by accident it may cause fluid to collect in your lungs
- abdominal pain, holes in the gut wall (intestinal perforation)
- blistering inside the nose or mouth
- severe skin disease (red, blistered, bleeding, painful skin, which may affect the lips, eyes, mouth, nose and genitals too)
- rash, redness of the skin
- swelling of the face
- fever, sweating
If you have any symptoms of the above, contact the emergency department or call 999 immediately. Your investigation will need to be stopped, and you may need further treatment.
Reporting of side effects:
If you get any side effects, talk to your doctor, radiologist or X-ray department staff. This includes any possible side effects not listed in this leaflet.
You can also report side effects directly to the United Kingdom Yellow Card Scheme Website: www.mhra.gov.uk/yellowcard
How to store Gastrografin?
- Keep this medicine out of the sight and reach of children.
- The product should be used within 72 hours once opened.
- Do not use this medicine after the expiry date which is stated on the label after EXPIRY.
- The expiry date refers to the last day of that month.
- Protect from light.
- Do not store above 25°C
Date of publication: 29/09/2022
Reference code: PIL199
Review date: 29/09/2025