Iodine-based contrast can improve the visibility of blood vessels, organs, inflammation and tumours during CT.
What is CT contrast?
CT contrast is a temporary substance that changes how X-rays pass through the body. Intravenous iodine contrast makes blood vessels and the blood supply of organs or lesions easier to see on CT images. Oral contrast may be used for selected bowel or abdominal examinations.
What will I feel?
When intravenous contrast is injected, it is common to feel warmth, flushing, a metallic taste or the sensation of passing urine. These usually last only a short time. The injection should not be painful beyond the cannula, so tell the radiographer immediately if you feel increasing pain or swelling around the injection site.
What should I tell the clinic?
- Any previous reaction to iodinated CT contrast.
- Kidney disease, dialysis, recent kidney injury or significant dehydration.
- Diabetes and whether you take metformin.
- Thyroid disease or planned radioactive iodine treatment.
- Asthma, severe allergies or current illness.
- Pregnancy, possible pregnancy or breastfeeding.
- All current medications and any instructions already provided by your doctor.
A food or shellfish allergy is not the same as a previous reaction to iodinated contrast. The most important allergy history is what happened during any earlier contrast injection.
Kidney function and metformin
Most patients receive iodinated contrast safely. Kidney function may be checked when risk factors are present. Do not stop metformin or another prescribed medication unless the clinic or your treating clinician gives you specific instructions.
After contrast
You will be observed briefly after the scan. Drink normally afterwards unless you have a medical fluid restriction. Mild delayed rash or itching can occur; severe reactions are uncommon but require urgent medical attention.
Related Patient Guides
- PG2001 – CT Scan: What to Expect Before, During and After Your Appointment
- PG2002 – What Is Spectral CT? A Simple Patient Guide
- PG2003 – Spectral CT in Cancer Imaging: What Patients Should Know
- PG2005 – Radiation Dose in CT: Understanding Risk, Benefit and Context
- PG2006 – Low-Dose CT Lung Screening: Preparation, Results and Follow-Up
- PG2007 – Coronary Artery Calcium Score: What the Test Can and Cannot Show
- PG2008 – CT Coronary Angiography: How to Prepare and What to Expect
- PG2009 – CT Angiography: Brain, Neck, Aorta and Peripheral Arteries
- PG2010 – Dental and Cone Beam CT: What to Expect
We have more detailed information on many interesting regenerative and radiological topics on our Insights page
Frequently Asked Questions
For other FAQs please visit our FAQs page
Is iodine contrast radioactive?
No. The contrast material does not produce radiation. The CT scanner uses X-rays.
Can I breastfeed after iodinated contrast?
Current professional guidance generally considers breastfeeding compatible with iodinated contrast. Discuss individual concerns with the clinic or your doctor.
Will I always need a blood test first?
No. Kidney-function testing is based on your age, history, current health, medications and the type of examination.
| Important: Seek urgent help for difficulty breathing, facial or throat swelling, faintness, rapidly spreading hives or severe symptoms after contrast. |
PATIENT GUIDE • PG-2004 [Patient information: Iodine-based contrast can improve the visibility of blood vessels, organs, inflammation and tumours during CT.]
For further reading on CT Scans please see below:
- Appendicitis CT Scan
- Chest CT Scan
- CT Scan for Back Pain
- Knee CT Scan
- Pulmonary Fibrosis
- Asbestosis CT Scan
- CT Abdomen Scan
- Heart CT Scan
- Lung CT Scan
- Sinus CT Scan
- Brain CT Scan
- CT Scan Calcium Score
- Kidney CT Scan
- Neck CT Scan
Comparing CT scans in Brisbane and the Gold Coast?
Patients travelling from Brisbane can access advanced Spectral CT at MBR Health on the Gold Coast, including specialised vascular, oncology, abdominal, pulmonary and material-analysis protocols only available at MBR Health.
MBR Health offers bulk billed CT on the Gold Coast for most standard diagnostic Spectral CT examinations where Medicare eligibility requirements are met.
