Not Medical Advice:
Some side effects of using contrast materials include: itching, hives, swelling of the throat, nausea and vomiting, headache, abnormal heart rhythms, and convulsions. Contrast materials are considered to be safe drugs, however, adverse reactions can occur, but severe reactions are uncommon.
Contrast materials, contrast agents, or contrast media are used to improve pictures of the inside of the body and allow the radiologist to distinguish normal from abnormal conditions. They are commonly used with x-rays, computed tomography (CT), magnetic resonance (MR) imaging, and ultrasound. They temporarily change the way imaging tools view the body, but they don't permanently discolor internal organs. Contrast materials can be taken orally, rectally, or intravenously and are eliminated through urine or bowel movements.