What it is used for
- X-rays of the gullet, stomach and bowel when barium is unsuitable, for example if a tear or leak is suspected
- Outlining the bowel before a CT scan
- Urinary tract and other X-ray tests by injection, now mostly replaced by newer dyes
- Sometimes in hospital as an enema or by mouth to help treat certain types of bowel blockage, as a specialist decides
How it is used
- The solution is drunk, sometimes diluted or given through a tube, before or during the test as the staff direct
- The enema and the injection into a vein are given only by the X-ray team
- Drink plenty of fluids after the test unless the staff tell you otherwise
Possible side effects
- By mouth or rectum: diarrhoea, nausea and vomiting
- By injection: a feeling of warmth, a metallic taste and nausea
- Allergic reactions such as rash and itching, and rarely a severe reaction
- Reduced kidney function after injection in people at risk
- Dehydration in infants and older people with the solution taken by mouth
Who should not use it
- A previous severe allergic reaction to iodine contrast dyes
- An uncontrolled overactive thyroid
- It must never be injected into the spinal canal
Before and while using it
- Tell the staff about any previous reaction to contrast dyes, asthma or allergies
- Tell the staff if you have kidney disease, or diabetes and take metformin
- Breathing the solution into the lungs while swallowing can cause serious lung inflammation; tell the staff if you have trouble swallowing
- Tell the staff if you have thyroid disease, as the iodine can affect it
- A delayed rash can appear hours or days later; tell your doctor if it happens
Medicine interactions
- Metformin may need a short pause around the injection in people with kidney problems, as the doctor decides
- Beta-blockers can make an allergic reaction harder to treat
- Interleukin-2 treatment increases the risk of delayed reactions
- It can affect thyroid test results for several weeks; tell your doctor you have had a contrast test
Pregnancy and breastfeeding
- Tell the staff if you are or might be pregnant, as the iodine can affect the baby's thyroid
- Breastfeeding can usually continue after the test
How to store it
- It is stored in hospital away from light
Get medical help straight away if
- Your face, lips or tongue swell, or you find it hard to breathe.
- You get a severe rash, blistering or peeling skin.
- A side effect worries you or doesn’t go away: contact your doctor or pharmacist.
Questions about this medicine?
Talk to a doctor by video, or send your question by text.
Source: Standard international medicine references
This guide is general information and doesn’t replace advice from your doctor or pharmacist. Don’t start, stop or change a medicine without asking them, and always read the leaflet in the pack.