How long do the after effects of an MRI last?

An MRI does not result in after effects, according to eMedicineHealth. MRI tests are safe, and neither the scan nor the contrast injection hurts people. Rarely, individuals may require sedation during the test. A sedated patient is released after the sedative wears off, and the patient is awake and alert.

The magnetic field emitted from an MRI machine may cause injury and harm to individuals with metal implanted in their body, according to eMedicineHealth. The magnetic field can cause certain metals to move. Patients with certain medical devices such as pacemakers, implanted pumps, nerve stimulators and aneurysm clips cannot enter an MRI machine.