Premedication Policy

A patient with a history of anaphylactoid reaction to allergens other than iodinated contrast does NOT need to be pre-medicated.
A patient should not receive contrast (iodinated oral or IV) if they have previously had an anaphylactoid reaction to non-ionic contrast unless, in the opinion of the physician, the procedure is needed as an emergency. Anaphylactoid reactions would include the following:
  • Difficulty breathing
  • Unconsciousness
  • Convulsions
A patient may benefit from pre-medication if they have had a significant reaction to non-ionic contrast in the past. Significant reactions would include the following:
  • Urticaria/Hives
  • Bronchospasm
  • Rash
Significant reactions would NOT include the following:
  • Nausea/Vomiting
  • Metal taste in mouth
  • Flushing
The radiologist should discuss pre-treatment in these situations with the referring clinician.
If the referring clinician wishes the study to continue without pre-treatment this must be documented in the report.
If the referring clinician agrees that pre-treatment is warranted they should be advised to prescribe:
  • 50mg Prednisone PO 13, 7 and 1 hour before the injection.
  • 50mg Benadryl (Diphenhydramine) IV/PO within 1 hour of the injection.
In an emergency setting an alternative faster (but less proven) regime is:
  • 200mg Hydrocortisone IV 4 hours before injection.
  • 50mg Benadryl (Diphenhydramine) IV/PO within 1 hour of the injection.
Pediatric Patients: (For patients less than 50kg):
  • Prednisone 0.7mg/kg (not to exceed 50mg) PO 13, 7 and 1 hour before the injection.
  • Benadryl (Diphenhydramine) 1mg/kg IV/PO (not to exceed 50mg) within 1 hour of the injection.
In an emergency setting an alternative faster (but less proven) regime is:
  • Hydrocortisone 1mg/kg (not to exceed 200mg) IV 4 hours before injection.
  • Benadryl (Diphenhydramine) 1mg/kg IV/PO (not to exceed 50mg) within 1 hour of the injection.


Adapted from: American College of Radiology Contrast Media Manual, 1998 and Rad-LS (Bush, WH, Krecke KN, King BF, and Bettmann MA (eds.), Oxford University Press, Inc., New York, 1999