Have to drink barium sulfate night before and morning of ct . scared of side effects or sever allergic reaction. i'm already constipated, cancel it?

Barium: Barium rarely causes allergic reactions,but can be very constipating. Usually an additive in the barium helps avoid constipation. Perhaps you can ask your physician to prescribe a vigorous laxative schedule for you instead of canceling the study. However if you're already severely constipated, you should get advice from your physician on what to do about the test.