One common approach to treating Graves' disease uses a strong dose of radioactive iodine to destroy cells in the thyroid gland. This procedure attempts to stop excess hormone production by thinning the ranks of cells responsible for making the hormones. The amount of radioactive iodine you get depends on the estimated size of the thyroid, determined either through a physical exam or by ultrasound. It also depends on the gland's level of activity, as indicated by the results of an iodine uptake test. Despite its destructive effect on thyroid cells, the iodine used in this procedure will not harm surrounding tissues and organs.
At the beginning of the treatment, you will be given a capsule or liquid containing the radioactive iodine. Either way you take it, you should not feel any effects as the substance enters your system. Most of the iodine will gather and stay in your thyroid. Excess amounts will be excreted in urine. It's a good idea to drink several extra glasses of water per day for about a week after the treatment to help flush the material out of your body as quickly as possible. To be on the safe side, you should also limit contact with infants, children, and pregnant women for at least 7 days after you take the iodine.
You probably won't notice any changes for several days after taking the radioactive iodine, but if your thyroid gland feels inflamed and sore, acetaminophen, ibuprofen, or aspirin can help. Over the next several months, the thyroid's hormone secretion should slowly begin to drop. During this time you need to see the doctor for periodic checkups to determine how well the treatment is progressing. Chances are good that a single dose of radioactive iodine will be enough to correct hyperthyroidism. But if the condition hasn't gotten better 3 or so months after your initial treatment, your doctor may give you a second dose of iodine. Once your doctor has decided your Graves' disease is under control, you'll still need to get routine checkups to make sure your thyroid levels remain within the normal range.