Enhanced CT is different from regular CT, so the side effects are more serious, but not everyone will have side effects. Today, we will introduce you the purpose and side effects of enhanced CT. Plain CT is a general scan without contrast enhancement or contrast. Enhanced CT refers to scanning after giving water-soluble iodine contrast agent intravenously. The increased concentration of iodine in the blood increases the density difference between the lesion and the adjacent normal tissue, thus increasing the lesion display rate. This allows the lesion to be more clearly visualized to reveal lesions that are not shown on plain scan or are poorly visualized, and to make a qualitative diagnosis of the lesion by the presence or absence of enhancement or the type of enhancement. The general situation is that the contrast agent tends to aggregate in areas with a rich blood supply. In addition to this, it is important to pay attention to the time of enhancement CT, and there are some cases where dynamic observation is more clinically relevant. General CT does not require contrast injection, which avoids the possibility of contrast allergy. In addition the radiation generated by the scan is harmful to the human body, ordinary CT only needs to scan the organ to be examined once, while enhanced CT needs to scan the area of interest repeatedly in succession at different times, which means that ordinary CT is less harmful to the human body than enhanced CT. So, what are the side effects of enhanced CT that require special attention? Allergic reactions, including itching, rash, flushing, nausea, vomiting, edema, etc., and in severe cases, laryngeal edema, anaphylactic shock, etc., and even life-threatening; renal impairment, mostly transient, and in very few patients, especially those with renal insufficiency, may cause permanent renal impairment; vasovagal reactions, including pallor, weakness, sweating, nausea, vomiting, syncope, convulsions, incontinence angina pectoris; pulmonary edema; generalized heat, pain, or other discomfort; bleeding, pain, bruising, and leakage of contrast medium and swelling at the puncture site; infection; other unpredictable conditions.