The magnitude of iodine-131 side effects varies from person to person and is related to the dose taken as well as the patient’s physical condition. Iodine-131 is a destructive treatment that is used to treat hyperthyroidism or post-operative papillary thyroid cancer. If the dose of iodine-131 is high, hypothyroidism is most likely to occur and the patient may need to take eugenol for life. It is also common for patients to have abnormal blood cells and even bone marrow suppression. Some patients may have gastrointestinal reactions such as nausea and vomiting, while others may have pain in the neck and throat, painful swallowing, and radiation pharyngitis, which can be prevented by taking prednisone before treatment with iodine-131.