What are side effects of contrast agents used in MRI scans?

Anthony L. Komaroff, MD
Internal Medicine
Not all magnetic resonance imaging (MRI) scans require contrast agents, but a contrast agent is sometimes used to show blood vessels or the amount of blood flowing to a particular structure.

Most of the contrast agents for MRI scans contain a metal called gadolinium. The gadolinium is attached to other chemicals to keep it from causing any harm. If your kidneys are healthy, you'll excrete the contrast agent before that complex has a chance to break down. But if your kidneys aren't working well, it may break down before it is excreted, so unbound gadolinium persists in the body. When that occurs, it may lead to a complication called nephrogenic systemic fibrosis (NSF), which can thicken the skin and connective tissues throughout the body. While there are reports of NSF as far back as 1997, the association with gadolinium was first identified in Denmark in 2006. Since then, NSF has been recognized as an extremely rare but potentially debilitating complication of giving gadolinium-based contrast agents to patients with poor kidney function. As a result, it's now routine to screen patients for kidney function before giving contrast for an MRI scan. The screening isn't complicated: a simple blood test of creatinine levels is all that's needed. Some MRI centers can measure creatinine on the spot, so the blood sample doesn't need to be sent to an outside lab.

Patients also occasionally experience nausea or vomiting from MRI contrast agents. True allergic reactions are rare and usually mild (itching, a rash). Very infrequently, the contrast agent provokes an anaphylactic allergic reaction requiring emergency treatment. All of these rare complications can be minimized through appropriate screening of kidney function and allergy risk factors.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.