February 15, 2011

ACR-Proposed Premedication Regimen to Reduce Contrast Reactions

According to the version #7 (2010) ACR Manual on Contrast Media, the following regimens are recommended for premedication of patients at risk for developing contrast reaction.

Elective Premedication
  1. Prednisolone: 50 mg PO at 13 hours, 7 hours and 1 hour before contrast media injection, PLUS Diphenhydramine 50 mg IV, IM or PO 1 hour before contrast medium OR
  2. Methylprednisolone 32 mg PO 12 hours and 2 hours before contrast media injection. An anti-histamine (as in option 1) can be added. If unable to take oral medication, use hydrocortisone 200 mg IV instead
Emergency Premedication
  1. Methylprednisolone 40 mg or hydrocortisone 200 mg IV every 4 hours until contrast study required PLUS Diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
  2. Dexamethasone 7.5 mg or betamethasone 6 mg IV every 4 hours until contrast study PLUS diphenhydramine 50 mg IV 1 hour prior to contrast injection OR
  3. Omit steroid entirely and give diphenhydramine 50 mg IV
"IV steroids have not been shown to be effective when administered less than 4 to 6 hours prior to contrast injection."

ACR Manual on Contrast Media (7th version, 2010)


Behrang Amini, MD/PhD said...

It's been the little secret of radiology that these pre-treatment regimens are essentially useless, as 1) The likelihood of a second contrast reaction is 8%-25% (this doesn't even address the fact that these reactions may have more to do with stress/anxiety) and 2) Steroid pre-treatment may only be effective for minor reactions (does not protect against severe reactions). This is useless medical treatment at best and dangerous at its worst, because it gives a false sense of security.

It persists, however, for medicolegal reasons: "Doctor, you knew the patient was at a higher risk for a contrast reaction, and you didn't adhere to the standard of care?" will say the friendly lawyer. Another reason we residents love it is because the standard 13-hour treatment pushes the study onto someone else's shift :)

The ED literature has woken up to this (see Schabelman E, Witting M. The relationship of radiocontrast, iodine, and seafood allergies: a medical myth exposed. J Emerg Med. 2010 Nov;39(5):701-7.). They recommend: "Do not delay emergent studies for steroid premedication. Only lengthy 12-h premedication protocols have shown any effect on reaction rates, and this small benefit was manifested primarily by decreasing minor reactions. No steroid protocol has shown a significant benefit in decreasing severe or fatal reactions."


Alergic reaction with contrast are due to histamin release from the mast cells and basophil cells. So, the pre-medication and treatment should include H1 and H2 blockers + shortacting or long acting steroids is the treatment of choice.

Dr Sushma Saroa,
Department of Radiology,
Sir Ganga Ram Hospital(SGRH)

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