Thyroid Cancer Overview

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Treating Thyroid Cancer TOPICS

Radioactive iodine treatment for thyroid cancer

The thyroid gland absorbs nearly all of the iodine in your body. When radioactive iodine (RAI), also known as radioiodine or I-131, is taken into the body as a liquid or capsules, it collects in thyroid cells (including cells from differentiated thyroid cancer) and kills them. RAI is a way to kill these cells, with little effect on the rest of the body.

This treatment can be used to destroy any thyroid tissue not removed by surgery or to treat some types of thyroid cancer that have spread to lymph nodes and other parts of the body.

Risks and side effects

Your body will give off radiation for some time after you have RAI treatment. How much will depend on the dose used. You might need to be in the hospital for a few days after treatment, staying in a special room to keep others from being exposed to radiation. Some people might not need to stay in the hospital. Once you are allowed to go home after treatment, you will be told how to protect others from radiation and how long you need to do this. These instructions may vary slightly by treatment center. Be sure you know what to do before you leave the hospital.

Short-term side effects of RAI treatment may include:

  • Neck soreness and swelling
  • Nausea and vomiting
  • Salivary glands being tender and swollen
  • Dry mouth
  • Taste changes

Chewing gum or sucking on hard candy may help with salivary gland problems.

Longer term side effects can include

  • Dry eyes because tear production is affected
  • Lower sperm counts in men, or even being unable to father a child
  • Irregular periods in women for up to a year after treatment
  • Slightly higher risk of getting leukemia in the future.

Talk to your health care team if you have any questions about the possible risks and benefits of your treatment.


Last Medical Review: 02/27/2014
Last Revised: 02/27/2014