What are the risks of cardiac magnetic resonance imaging?

Cardiac magnetic resonance imaging (MRI) produces no side effects from the magnetic fields and radio waves. This method of taking pictures of organs and tissues doesn't carry a risk of causing cancer or birth defects.
Serious reactions to the contrast agent used for MRI are very rare. However, side effects are possible and include the following:

• Headache
• Nausea (feeling sick to your stomach)
• Dizziness
• Changes in taste
• Allergic reactions

Rarely, the contrast agent can be harmful in people who have severe kidney or liver disease. It may cause a disease called nephrogenic (NEF-ro-JEN-ik) systemic fibrosis.
If your cardiac MRI includes a stress test, more medicines will be used during the test. These medicines may have other side effects that aren't expected during a regular MRI scan, such as:

• Arrhythmias (ah-RITH-me-ahs), or irregular heartbeats
• Chest pain
• Shortness of breath
• Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast)

This answer from the National Heart, Lung and Blood Institute has been reviewed and/or edited by Dr. William D. Knopf.