iohexol at a glance
Medicine class
Non-ionic iodinated X-ray contrast agent
Main role
Improves diagnostic images during CT and other X-ray-based procedures
Administration
Given by trained healthcare professionals; the route depends on the examination
After injection
A brief warm feeling or metallic taste can occur
What is iohexol used for?
Licensed uses are diagnostic rather than therapeutic.
CT image enhancement and examinations of the urinary tract and veins
Imaging of arteries, the heart and blood vessels
Myelography and CT cisternography
Imaging of joints, salivary glands, the gastrointestinal tract and selected body cavities
Imaging during ERCP and investigations of hernias or the uterus and fallopian tubes
Contrast-enhanced mammography in adults where clinically appropriate
How does iohexol work?
Its iodine atoms strongly absorb X-rays, making areas containing iohexol appear more clearly against surrounding tissues. It helps identify anatomy or abnormalities but does not treat the condition being investigated.
How to take iohexol
Iohexol is administered during a hospital or imaging-department procedure and should not be self-administered.
Follow the eating, drinking and medicine instructions in your appointment letter because preparation varies by examination.
Tell staff about previous contrast reactions, asthma, kidney or thyroid disease, diabetes, pregnancy, breastfeeding and all medicines you take.
Maintain hydration before and after administration as directed by the clinical team.
Remain for any requested observation period after injected contrast.
iohexol side effects
Common or expected effects
- Temporary warmth or flushing
- Headache, especially after administration into the spinal fluid
- Nausea or vomiting
- Brief metallic taste
- Mild injection-site pain or discomfort
Get urgent medical advice
- Breathing difficulty, wheezing, collapse, or swelling of the face or throat
- Seizure, marked confusion, loss of consciousness, visual disturbance, weakness or speech difficulty
- Acute kidney injury
- Severe or blistering skin reaction
- Severe or increasing injection-site pain and swelling, particularly with altered sensation or skin changes
- Thyrotoxicosis or clinically important thyroid suppression
iohexol in pregnancy
Tell the imaging team if you are pregnant or could be pregnant. Iohexol should be used only when the expected diagnostic benefit outweighs the risks, including X-ray exposure and a possible effect on the fetal thyroid. Neonatal thyroid testing is advised after exposure during pregnancy, with additional follow-up particularly for premature or low-birth-weight babies.
iohexol while breastfeeding
Breastfeeding can normally continue after iohexol. Very little reaches breast milk and little of that is absorbed by a healthy full-term infant; seek specialist advice if the infant is premature or unwell.
iohexol interactions
Give the radiology team a complete medicine list because some medicines alter risk or require additional planning.
Metformin
Temporary kidney impairment after iodinated contrast can increase the risk of lactic acidosis, so kidney function and metformin management may need review.
Interleukin-2 or interferons
Recent treatment has been associated with more delayed flu-like or skin reactions.
Tricyclic antidepressants and some antipsychotics
These can lower the seizure threshold and may increase contrast-associated seizure risk.
Common questions about iohexol
Answers are fully visible for fast scanning and source review.
Is iohexol radioactive?
No. It contains iodine that blocks X-rays but is not itself radioactive.
Why did iohexol make me feel warm?
A short-lived warm or flushing sensation is a recognised effect of injected contrast and usually passes quickly.
Can a reaction happen after I leave hospital?
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.