The amount of radioactivity is very small, and there have been no documented side effects. The amount of iodine used is less than the amount of iodine in a normal diet. However, as with any radiation exposure, this test is not recommended for women who are pregnant or breastfeeding.

People with a history of allergy to dietary iodine or shellfish may not be able to have this test. A history of allergy to iodine (contrast dye) does not necessaily mean you can't have this test. Talk to your health care provider.

The radioactive iodine leaves your body through your urine. You may need to take special precautions, such as flushing twice after urinating, for 24 - 48 hours after the test. Ask your health care provider or the radiology/nuclear medicine employee performing the scan.