You leave the examination room, and a feeling of warmth lingers in your arm. Perhaps a slight nausea, a strange taste in your mouth. After an MRI, these little manifestations often surprise, especially when no one has mentioned them. Most disappear within a few hours. Some, rarer ones, warrant a call to the doctor without delay.
Checking implants before MRI: the underestimated risk
The most discussed side effects on forums concern nausea or headaches. However, the most serious incidents after an MRI are often related to a failure to check before the exam, not to the exam itself.
Read also : What are the possible side effects after the second dose of the shingles vaccine?
The magnetic resonance imaging machine generates a powerful magnetic field. This field can move or damage certain metallic devices present in the body. Cochlear implants, certain clips for brain aneurysms, and most pacemakers are formal contraindications to MRI.
On the other hand, a joint prosthesis, an artificial heart valve, or orthopedic screws are generally compatible. The safety questionnaire filled out before the exam exists to sort out these situations. If you have any doubts about an implanted device, inform the radiology team before entering the room.
See also : Very Leak: what are the legal responsibilities for hosts and their members?
A patient who experiences unusual localized pain, a burning sensation, or internal movement after the exam should report it immediately. This type of reaction is not just a simple transient side effect: it may indicate a problem related to the compatibility of an implant.
To better understand the side effects after an MRI and to distinguish a trivial symptom from a warning sign, one must first separate two very different situations: MRI without injection and MRI with contrast agent.
Side effects of an MRI without contrast injection
When the exam is conducted without contrast agent, reactions are rare and generally mild. MRI does not use ionizing radiation. The body is exposed to a magnetic field and radio waves, which explains that the risks differ completely from those of a CT scan.
The sensation of warmth during the exam is the most common reaction. It comes from the energy of the radio waves absorbed by the tissues. It disappears as soon as the exam is over.
Some patients also report vibrations, slight dizziness when exiting the tunnel, or a transient metallic taste. These manifestations do not require any management.
Fatigue and headaches after the exam
Unusual fatigue or moderate headaches sometimes occur in the hours following. Prolonged immobility, the loud noise of the machine, and the stress of the exam contribute as much as the magnetic field itself.
These symptoms generally fade on their own. If a headache persists beyond twenty-four hours or is accompanied by visual disturbances, it is better to contact your doctor.
Reactions to gadolinium: the contrast agent in MRI
About one in three MRI exams requires the injection of a gadolinium-based contrast agent. This product enhances image quality, particularly for visualizing blood vessels, tumors, or inflammations.
Gadolinium is eliminated by the kidneys. In a patient with normal kidney function, the plasma half-life is about 90 minutes. In other words, the body gets rid of it quite quickly.
Common minor reactions after injection
The most frequent side effects after injection remain benign:
- Mild nausea or a diffuse feeling of warmth in the minutes following the injection, disappearing in less than an hour
- Metallic taste in the mouth, sometimes perceived right at the injection, which fades spontaneously
- Pain or redness at the injection site, related to the passage of the product into the vein (and sometimes to extravasation, meaning leakage of the product outside the vessel)
- Moderate headaches in the following hours, comparable to those of an MRI without injection but slightly more frequent
These reactions disappear without treatment in the vast majority of cases. Drinking water after the exam helps the kidneys eliminate gadolinium more quickly.
Allergic reactions to gadolinium
Hypersensitivity reactions to the contrast agent do exist but remain exceptional. They manifest as hives, localized swelling (Quincke’s edema), or in the most severe cases, difficulty breathing.
Any generalized hives or facial swelling after a gadolinium injection warrants immediate consultation. These signs can appear within minutes or hours following the exam.
When to seek emergency care after an MRI
The difficulty after an imaging exam lies in sorting out a trivial symptom from a sign that requires prompt management. Here are the situations that should not wait:
- Difficulty breathing or a feeling of chest tightness that appeared after the exam
- Swelling of the face, lips, or throat
- Extensive hives over several areas of the body
- Persistent vomiting that does not subside within an hour
- New neurological symptoms: sudden numbness, speech disturbances, confusion, or loss of strength in a limb
- Fainting with a drop in blood pressure or loss of consciousness
These signs may indicate a severe allergic reaction to the contrast agent or, more rarely, a problem related to an undetected implant. In both cases, call 15 (emergency services) or go to the emergency room without delay.
Kidney failure and nephrogenic systemic fibrosis
Patients with kidney failure present a particular risk after a gadolinium injection. The contrast agent, poorly eliminated by failing kidneys, can in rare cases cause a condition called nephrogenic systemic fibrosis (NSF). This disease affects the skin, joints, and internal organs.
A renal assessment is systematically requested before any gadolinium injection in at-risk patients. If you know that your kidney function is impaired, remind the radiologist before the exam.
Most people undergoing an MRI do not feel anything unusual after the exam, or only experience transient fatigue. The side effects related to gadolinium remain mostly benign and short-lived. The only reflex to keep in mind: any respiratory, allergic, or neurological symptom that appears in the hours following the exam deserves a call to the doctor or to 15, without hesitation.