Are there any harmful effects of a mri on the brain?

Not likely: An MRI is a test that uses a magnetic field rather than conventional radiation and so is real safe. The largest contraindication/risk is if you have a metallic implant that might migrate in the magnetic field, but this is usually carefully screened before doing the mri. Thank you.

I would say none: It is the MRI facilites job to determine if you have a pacemaker or aneurysm clip or metal implant which precludes you from having an mri. So... If you are pre screened and ok to have an MRI - MRI itself has no harmful effects. It does not use ionizing radiation. It uses safer contrast than ct contrast. If you facility uses eovist, ProHance or MultiHance - these contrasts do not cause nsf.