Contrast reaction prophylaxis

13 hours prior to exam: Prednisone 50 mg PO

7 hours prior to exam: Prednisone 50 mg PO

1 hour prior to exam: Prednisone 50 mg PO AND Diphenhydramine 50 mg PO

12 hours prior to exam: Methylprednisolone 32 mg PO

2 hours prior to exam: Methylprednisolone 32 mg PO

1 hour prior to exam: Diphenhydramine 50 mg IV/IM/PO (optional)

15-30 minutes prior to CT: Methylprednisolone 125 mg IV push AND Diphenhydramine 25-50 mg IV push

Every 4 hours until procedure: Methylprednisolone 40 mg or Hydrocortisone 200 mg IV

Immediate pre-procedure: Diphenhydramine 50 mg IV

Note: Premedication regimens shorter than 4–5 hours in duration (oral or IV) have not been shown to be as effective. When possible, patients should receive at least two steroid doses prior to intervention. Urgent/emergent procedures should not be delayed solely for additional steroid premedication; timing should be adjusted based on clinical judgment.