Contrast media are the materials utilized in radiology to improve the visualization of certain body structures subjected to analysis in a medical image. Contrast media are, then, diagnostic drugs because they increase the visibility of organs and tissues and allow the identification of details that otherwise could not be observed. With the introduction of multidetector computed tomography the number of patients undergoing contrast studies has grown exponentially in recent years. In computed tomography the formation of the radiographic image is obtained with the use of contrast media containing iodine atoms, exploiting the different attenuation that the X-ray beam presents in crossing the anatomical districts. The Iodinated Contrast Media (ICM) are a category of numerous substances formed by even complex molecules that vary considerably in their properties, uses and toxic effects. Even though iodinated contrast agents have a good safety profile, it is necessary to understand that some patients can have severe, life-threatening allergic reactions because of the side effects of the chemicals. This paper describes the clinical pharmacology, use and adverse reactions of intravenous iodinated contrast media used in computerized tomography, offering all doctors, even non-radiologists, the opportunity for rapid updating.