Diagnostic and interventional radiology of patients is nowadays crucial with increasing requirement for iodinated contrast agents infusion. Besides adverse reactions after administration of the iodinated contrast agents due to their toxicity, immediate hypersensitivity reactions and reactions resembling delayed hypersensitivity appearing from 1 hour to several days later, have been reported. Patients at high risk to develop such adverse events have to be detected on the basis of their risk factors in order to prevent or limit serious outcomes. Previous reactions to contrast media, asthma, atopy and cardiovascular disorders are risk factors for anaphylactic or anaphylactoid reactions. Female gender, age and beta-blockers increase the severity. This article aims to summarize the risk of allergic reactions related to the use of iodinated contrast agents and to suggest a way for diagnosis, treatment and prevention according to each clinical situation.