I had a HIDA scan a few weeks ago and there were no side effects, its not much fun if you don't like enclosed spaces, but all you do is lie there so not so bad raelly.
Ditto what UK said. The amount of radiation is very small and localized, and there are no side effects to the test. Honestly, it's really very boring. I don't remember feeling enclosed, at least not like an MRI.
One thing you want to be sure to tell the techie is if you feel at all nauseated when they give you an injection that makes the gallbladder contract. That's when they measure how much bile the gb expels and they can measure how effective your gb is operating.
Thank you for taking the time to give me info on personal experience and for reassurance. I feel a little better.