Premedicate Fast and Only in Patients with a History of Contrast Reaction

Recommendations for premedicating inpatients with a risk of contrast media reactions have changed over the years. New ACR guidelines from 2017 propose a restrained use – this is partly due to the indirect harms of premedication.

For a long time, methylprednisolone twice – 12 and 2 hours prior to the scan – has been used to premedicate patients at risk of developing contrast media reactions.

The first study on this topic from Lasser et al. (1987) showed this premedication decreases immediate adverse events in average risk patients. Lasser’s second study (1994) with low-osmolar agents (LOCM) showed that methylprednisolone twice 12 and 2 hours prior to the scan decreased mild events from 1.9% to 0.2%, while the aggregate risk decreased form 4.9% to 1.7%. However, decreases for moderate to severe events were not significant, probably due to the small patient number. The studies were underpowered for moderate to severe reactions. “This is the patient group we care most about,” said Ben Mervak, University of North Carolina, Chapel Hill/NC, USA.

569 Patients Treated = 1 Severe Reaction Prevented

In 2015, Mervak did a retrospective study with 1051 premedicated patients. He found a 1.4% decrease in overall reactions to contrast media.

When he took a closer look at reaction severity, he calculated that in patients with a prior reaction to contrast media

  • one needs to treat 69 patients to prevent one reaction
  • one would have had to treat 569 patients to prevent a severe reaction, and
  • approximately 56,900 patients would have to be treated to prevent one lethal reaction.

“Premedication makes a difference, but it is small, breakthrough reactions still happen, and many patients need to be premedicated to prevent a single reaction,” said Mervak. 

Risks of Premedication

Premedication is not entirely without risk. Historically, its direct risks were considered. Transient hyperglycemia may occur after corticosteroids, particularly in diabetics. Allergies to corticosteroids exist, although they are rare. There are also reports of cardiac arrhythmia from large, rapid IV doses; however, these doses are not used for premedication, commented Mervak. “The premedication is unlikely to cause significant clinical adverse outcomes as direct risks,” he said. 

Indirect Risk

This is different for indirect risks, such as delays in care, increased cost of care, and hospital-acquired infections.

In 2015, a retrospective study by Davenport showed that premedicated patients experienced a 25-hour delay before they got their CT. They stayed 25 hours longer in the hospital and had 2% more infections (5.1% versus 3.1%). 

Translated to cost this means: Calculated premedication cost due to delays is more than 150,000 US$ to prevent one reaction of any type and over 131,000,000 US$ to prevent a single lethal reaction. 

The numbers of hospital-acquired infections compared to one prevented reaction are also impressive: To avoid any reaction, 0.7 infections need to be taken into account. For each prevented severe reaction, 5.5 infections are caused. For one prevented lethal reaction, 551 infections will develop.

Some infections will lead to death: In the attempt to prevent one lethal reaction with premedication, 32 deaths from infection will occur. “This means we kill more than we save”, said Mervak. 

Prep Faster!

“We need to prep faster!” demanded Mervak. Results from his recent retrospective study (Mervak 2017) comparing a 5-hour rapid IV regimen versus the old 13-hour oral regimen showed that the breakthrough rates for both regimens were non-inferior to each other. 

Who needs premedication?

The ACR guidelines have caught up with the developments and have changed in 2017. They now state that radiologists should only premedicate patients with a history of contrast allergy. A 5-hour IV prep should be used for inpatients and ED patients when premedication will adversely delay care decisions. “This is basically always,” said Mervak. 

Take-home points

1. Premedication makes allergic-like reactions slightly less common, but does not completely prevent reactions.
2. Many patients must be premedicated to prevent a reaction. It needs more than 56,000 premedications to prevent one lethal reaction.
3. The direct risks of premedication are low, but the indirect risks are great.
4. Consider a 5-hour IV premedication for inpatients and ED. This rapid prep is non-inferior to 13-hour oral premedication.
5. Only premedicate patients with a history of contrast reaction


Davenport MS et al. Indirect Cost and Harm Attributable to Oral 13-Hour Inpatient Corticosteroid Prophylaxis before Contrast-enhanced CT. Radiology. 2016;279(2):492-501

Lasser EC et al. Pretreatment with corticosteroids to alleviate reactions to intravenous contrast material. N Engl J Med. 1987 Oct 1;317(14):845-9.

Lasser EC et al. Pretreatment with corticosteroids to prevent adverse reactions to nonionic contrast media AJR Am J Roentgenol. 1994 Mar;162(3):523-6.

Mervak BM et al.Rates of Breakthrough Reactions in Inpatients at High Risk Receiving Premedication Before Contrast-Enhanced CT. AJR Am J Roentgenol. 2015 Jul;205(1):77-84.

Mervak BM et al.Intravenous Corticosteroid Premedication Administered 5 Hours before CT Compared with a Traditional 13-Hour Oral Regimen. Radiology. 2017 Nov;285(2):425-33.

Presentation Title: Use of Iodinated and Gadolinium-based Contrast Media 2018: Is Your Clinical Practice Up to Date? Premedication: Is it worthwhile?
Speaker: Benjamin Mervak - University of North Carolina, Chapel Hill
Date: 2018-11-27
Session code: RC407-2