The incidence of acute iodine contrast media reactions, appearing within the first hour after the procedure, is low but clinically important due to their daily use. Previous adverse reactions to iodinated contrast media, asthma and a history of allergic reaction are the most recognized risk factors, but the identification of patients at risk remains difficult. The efficacy of preventive measures such as corticosteroid and/or antihistaminic administration rests on low-level evidence. Practical recommendations are presented in this article. Rather than relying on the sole administration of a premedication, the importance of other measures must be stressed: assessing the relevance of the indication to the radiologic exam, use of low osmolarity contrast media, and ensuring a proper monitoring of the patient during and after the procedure.