Adverse reactions to radiological contrast media: Prevention and treatment

Radiological contrast media, both iodinated and gadolinium-based, can lead to adverse reactions. Type A reactions are related to the pharmacological characteristics of the contrast, including side, secondary and toxic effects. Post-contrast acute kidney injury is the most frequent adverse reaction to iodinated contrast media. Less frequently, thyroid, neurological, cardiovascular, haematological, and salivary gland effects are also detected. With gadolinium-based contrast agents, nausea is the most frequent reaction, but there is also a risk of producing nephrogenic systemic fibrosis and cerebral deposits of uncertain significance. The most effective way of avoiding type A reactions is to decrease the dose and frequency of contrast media administration, especially in patients with pre-existing renal insufficiency. To prevent post-contrast acute kidney injury, adequate hydration of the patient should be maintained orally or intravenously, avoiding prolonged periods of liquid fasting. On the other hand, hypersensitivity reactions are dose-independent and clinically can range from mild cutaneous reactions to anaphylaxis. This article proposes an algorithm that differentiates between nonspecific reactions and true hypersensitivity reactions, as well as levels of severity. It also provides a treatment scheme for immediate reactions adjusted to the severity level, with a focus on the management of anaphylaxis and an early intramuscular administration of adrenaline. Finally, it sets out recommendations for the management of patients with previous hypersensitivity reactions who require elective or urgent contrast administration, favouring the use of alternative contrast media with confirmed tolerance instead of the indiscriminate use of premedication.