A lot of people can be very afraid of an MRI scan if it's the first time going through with it. It's ok to be anxious, but in the end, there is little to worry about.
Most of the side effects of an MRI scan are due to the uncomfortable nature of the scanning procedure. You must lay still for up to a half an hour in an enclosed MRI. A conventional MRI does not give much room for you to lay down either. The cramped up feeling, along with the loudness of the machine, can cause some anxiety.
Some side effects include dizziness and nausea. It is also likely that you will have a headaches afterwards too. But really, these side effects of MRI scans are not a big deal and will be shaken off given some time after your scan