As with treatment for hyperthyroidism, the iodine is given by mouth. The amount of iodine used is generally governed by where and how the disease has spread. When the disease has spread to the bones, radioiodine therapy may be followed by standard radiation therapy to the affected area. Complications and Precautions Patients treated with radioiodine for thyroid cancer may experience nausea for a few hours after the iodine is given. In order to flush out the iodine not taken up by the cancer, patients are asked to drink as much fluid as they can tolerate for one to two days.
Some patients experience a dry mouth after radioiodine therapy for thyroid cancer.
Unless exceptionally high doses of radioiodine are employed there are no known long-term risks. Since the thyroid has usually been removed prior to treatment, the patients are already hypothyroid. Patients on thyroid medication cannot be treated. These medications block the uptake of radioiodine. Patients should be off the most common thyroid medications for about a month.