Pretreatment Regimen for Patients with History of Contrast Allergy
Standard Pretreatment Protocol
- The American Heart Association recommends a pretreatment regimen of 50 mg of prednisone administered 13 hours, 7 hours, and 1 hour before the procedure, plus 50 mg of diphenhydramine 1 hour before the procedure for patients with a history of anaphylactoid reaction to contrast media 1, 2, 3
- The standard oral regimen consists of prednisone 50 mg at 13 hours, 7 hours, and 1 hour before contrast administration, and diphenhydramine 50 mg 1 hour before contrast administration, which reduces recurrence rates of anaphylactoid reactions from 16-44% to nearly zero 1, 2, 3, 5
- Many institutions use 60 mg of prednisone the night before and morning of the procedure, plus 50 mg of diphenhydramine 1 hour before the procedure, as an alternative regimen 1, 3
Additional Considerations
- The American College of Radiology suggests that switching to a different contrast agent may be more effective than premedication alone for patients with prior contrast reactions, and recommends considering alternative non-contrast studies when possible 7, 8, 4
- A severity-based approach is recommended, where agent switching is used for mild to moderate previous reactions, and both agent switching and premedication are used for severe previous reactions 7, 8, 4
- Patients with a history of severe reactions should be treated in a hospital setting with rapid response team availability, regardless of premedication 7, 9