There is also a small risk of an allergic reaction to iodinated contrast when it is injected. This is not a risk for contrast that is swallowed. It is not possible to predict whether you will be allergic to iodinated contrast, and even if you have had it before and not had an allergic reaction, this does not mean you will not have one the next time you have a contrast injection. The staff at the hospital or radiology practice are well trained to deal with allergic reactions should they arise. It is important to make the radiographer or nurse aware of any other allergies that you may have before having the injection. If you are allergic to other foods or drugs, it increases the chance that you will have an allergic reaction to iodinated contrast.