... with contrast and just took 2 Benadryl prior to my ct scan. My doctor prescribed 50mg because I have some allergies to seafood but this high dose made me feel sick for a previous ct scan. I eat shrimp, clams, haddock and tuna with no allergies to these. Just wondering if I cut the (3) 50mg tablets of prednisone in half and did half the dose it would be enough? Thanks