MRI With Contrast Side Effects
Magnetic resonance imaging (MRI) sometimes uses an injectable contrast dye to make tissues and abnormalities easier to see. Most MRI contrast agents contain gadolinium. They help radiologists spot small tumors, inflammation, infection, blood vessel problems, and more. Like any medicine, contrast can have side effects. This article explains the side effects and how radiology teams keep you safe.
What is MRI contrast?
MRI contrast is a liquid injected into a vein during the scan. It circulates through the bloodstream and changes the MRI signal in certain tissues. This allows more abnormalities to be seen and further characterized. Gadolinium is tightly bound to a carrier molecule to reduce toxicity and is eliminated mostly through the kidneys.
Common, mild side effects
Most people have no problems. When side effects occur, they are usually brief and mild:
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A cool feeling in the arm during injection
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Metallic taste in the mouth that fades quickly
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Nausea or mild headache that resolves on its own
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Temporary dizziness or a sense of warmth
Allergic-like reactions: uncommon but possible
Allergic-like reactions to gadolinium contrast are less common than reactions to iodinated CT dye. When they happen, they are usually mild:
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Itching or hives
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Sneezing or runny nose
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Mild swelling
Rarely, people can have more serious reactions such as wheezing, throat tightness, or low blood pressure. Radiology departments are trained and equipped to treat these events. If you have had a prior reaction to MRI contrast or severe allergies (for example, to multiple medications), tell your care team in advance. Premedication may be considered in select cases.
Kidney function and nephrogenic systemic fibrosis (NSF)
In people with severely reduced kidney function, certain older gadolinium agents were linked to a very rare condition called nephrogenic systemic fibrosis (NSF). It causes skin thickening and joint stiffness. Modern practice has dramatically lowered this risk:
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Kidney function is checked in high risk patients such as those with known kidney disease or recent chemotherapy that could affect kidneys.
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Safer “macrocyclic” agents are preferred because they hold on to gadolinium more tightly.
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Doses are kept as low as necessary, and contrast is avoided when it will not add value.
If your kidneys are working well, the risk of NSF is essentially negligible. If your kidneys are severely impaired, your radiologist will weigh benefits and risks or choose a non-contrast MRI when appropriate.
Gadolinium retention: what we know
A small amount of gadolinium can remain in the body for months to years. Trace amounts have been detected in the brain, bone, and skin after multiple contrast MRIs, even in people with normal kidneys. To date, scientific groups have not established a clear link between this retention and health problems in people with normal kidney function. Out of caution, radiologists:
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Use contrast only when it will improve diagnosis
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Choose agents with strong safety records
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Track cumulative exposure in patients who need many scans
If you are concerned about retention, ask whether a non-contrast MRI could answer the clinical question or whether ultrasound/CT might be alternatives. Often, contrast provides important information that changes treatment decisions.
Pregnancy and breastfeeding
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Pregnancy: Contrast MRI is used during pregnancy only when the information is expected to significantly affect care and cannot be obtained another way. Discuss timing and alternatives with your clinician and radiologist.
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Breastfeeding: Only tiny amounts of gadolinium enter breast milk, and even less is absorbed by the baby’s gut. Most guidelines say it is safe to continue nursing without interruption. If you prefer, you can pump and store milk before the exam.
What happens during the injection
A technologist places a small IV in your arm or hand. Contrast is injected through a pump or less commonly by hand. You might feel:
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A brief cold sensation along the arm
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Pressure at the IV site
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A need to swallow due to a metallic taste
Let the team know immediately if you feel pain, burning, or swelling at the IV site, which can signal leakage under the skin. This is usually minor and treated with elevation and cool compresses.
Who is more likely to have a reaction?
Risk is still low overall, but it is higher if you have:
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A past reaction to MRI contrast
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Severe or multiple drug allergies
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Uncontrolled asthma
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Severe kidney disease
Share your history before the scan. The radiologist can adjust the plan: choose a different agent, premedicate, or proceed without contrast.
How radiology teams reduce risk
Safety is built into every step:
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Careful screening for allergies, kidney disease, and pregnancy
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Choosing an agent with a strong safety profile
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Using the lowest effective dose
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Monitoring during and after injection
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Emergency medications and equipment on hand
These measures make serious complications rare.
When to call your doctor after MRI
Seek medical advice if you develop:
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Worsening rash, swelling, or breathing trouble
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Ongoing pain or redness at the IV site
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Persistent headaches, nausea, or new neurological symptoms
Provide the date of your MRI, the facility name, and that you received gadolinium contrast.
Balancing benefits and risks
Contrast MRI often answers questions that non-contrast imaging cannot—distinguishing cancerous lesions, assessing extent of inflammation, evaluating blood vessels, and detecting active infection. For most patients with normal kidneys, the benefits of an accurate diagnosis outweigh the small risk of side effects. If you have risk factors, your radiologist will tailor the exam.
Practical tips before your scan
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Bring a list of your medications and allergies
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Tell the team about your medical history
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Ask whether contrast is essential for your specific question
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Stay well hydrated unless your doctor advises otherwise
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Report any unusual symptoms right away
Conclusion
MRI contrast is a key tool that helps radiologists see disease clearly. Most people have no side effects or only mild, short-lived symptoms. Serious reactions are rare, and safeguards are in place to handle them. If you have kidney disease, a history of contrast reaction, are pregnant or breastfeeding, discuss options with your care team. The goal is always the same: answer the clinical question while keeping you safe.
References
https://www.radiologyinfo.org/en/info/safety-contrast
https://my.clevelandclinic.org/health/diagnostics/4876-magnetic-resonance-imaging-mri