Allergy to radiographic contrast media Hypersensitivity reactions to radio-contrast media are common in the daily practice. These products are responsible for immediate (< or = 1 hour after administration) and non immediate (> 1 hour after administration) hypersensitivity reactions. A diagnostic work-up by an allergologist with skin tests and in some cases provocation tests is of value in reducing the risk of recurrent hypersensitivity reactions to iodinated contrast media. A careful selection of the patients is required because the incidence of breakthrough reactions is still concerning, even with proper premedication. Practical recommendations are presented in this article. For gadolinium-based contrast agents, data in the literature is not sufficient for suggesting guidelines.