The barium sulfate used in a barium swallow is a non-radioactive contrast agent that will help your doctor
to better see the outline of your throat and esophagus. The addition of the barium to your swallow allows the normal x-ray
to visualize soft tissue that is normally invisible. The multiple x-rays repeated at different phases of your swallow will allow your doctor to note if there is anything abnormal or concerning about your swallow itself, and for that reason it is often used in the hospital to determine if patients are safely able to tolerated food by mouth after a long period of nothing by mouth (NPO, in doctor words).
Because it is not radioactive in and of itself, the risks of radioactivity come just from the x-ray itself. The barium then becomes just like anything else (e.g., food or liquid) that you ingest, and will pass in the normal amount of time that it takes for you to have a bowel movement. Usually, it will have passed completely in 2-3 days. Please discuss your concerns with your doctor prior to performing the procedure, and especially note your history of intestinal issues, although these are usually well tolerated.