What are common side effects of barium swallow and barium meal tests?

Not many. Barium contrast is inert usually without reaction. Constipation from barium can occur. Usually not permanent side effects. Do receive some irradiation from the test. Most radiologists try to keep dose of radiation as low as possible.
See below. These are generally quite benign tests. The most common complaints are nausea, vomiting, bloating, cramping and diarrhea all of which usually resolved within 1-3 days.