The American College of Radiology has issued new guidelines to help doctors prevent and manage allergic reactions to iodinated contrast media (ICM) used in CT scans and other imaging tests.
The American College of Radiology has issued new guidelines to help doctors prevent and manage allergic reactions to iodinated contrast media (ICM) used in CT scans and other imaging tests.
The Journal of Radiology, May 2025.
Key points made simple:
• Mild allergy in the past?
No need for premedication. If possible, use a different contrast agent than the one that caused the reaction.
• Severe allergy before?
Try to avoid ICM. If it’s absolutely needed:
→ Use premedication
→ Do the scan in a hospital with emergency support
• Reactions like nausea, vomiting, or feeling warm?
These are not true allergies. No premedication is needed.
• Shellfish or iodine allergy?
These do not increase risk of contrast allergy. No need for special action.
• Important:
Always write clear notes in the medical record:
• What were the symptoms?
• How long after the injection did they start? Why timing matters?:
• Within 1 hour (Immediate reaction):
→ Likely a true allergy (e.g., rash, wheezing, anaphylaxis)
→ May need premedication or contrast change in future
• After 1–24+ hours (Delayed reaction):
→ Usually mild skin rash or joint pain
→ Often does not require premedication
• Within seconds (Very rapid):
→ Likely non-allergic (e.g., anxiety, vagal response)
→ No need for special precautions
• What contrast was used?
