What is radioactive iodine treatment?

Radioactive iodine treatment uses radioactive iodine medication to treat thyroid cancer or an overactive thyroid (hyperthyroidism). The thyroid gland efficiently absorbs and concentrates iodine. Once in the thyroid, radioactive iodine destroys thyroid cancer cells, as well as the thyroid. Radioactive iodine treatment, also called radioiodine therapy or I-131 treatment, is available in a capsule or liquid form.

Radioactive iodine treatment is only one method of treating thyroid diseases, disorders and conditions. Discuss all your treatment options with your doctor to understand which options are right for you.

Other procedures that may be performed

Your doctor may recommend one or more additional procedures to treat thyroid cancer or hyperthyroidism including: 

  • Chemotherapy uses medications to slow or stop the growth of thyroid cancer cells.
  • External radiation therapy uses X-ray beams to kill thyroid cancer cells.
  • Surgery removes an overactive thyroid gland. You may also need surgery to remove all or part of a cancerous thyroid and possibly lymph nodes in the neck if the thyroid cancer has spread.
  • Thyroid hormone therapy uses drugs to prevent your body from making thyroid hormones or blocks their action to stop cancer cells from growing.

Why is radioactive iodine treatment performed? 

Your doctor, typically an endocrinologist, may recommend radioactive iodine treatment to treat thyroid cancer or an overactive thyroid gland, also called hyperthyroidism and Graves’ disease.

Who performs radioactive iodine treatment?

The following types of doctors determine the type and dose of oral radioactive iodine used in treatments:

  • Nuclear medicine doctors specialize in using radioactive materials to diagnose disease and guide treatment plans.
  • Nuclear radiologists specialize in using imaging technologies and radioactive materials to diagnose and treat disease.
  • Radiation oncologists specialize in treating cancer and related diseases with radiation.
  • Oncologists specialize in diagnosing, treating and preventing cancer.
  • Pediatric hematologist-oncologists specialize in researching, diagnosing and treating blood disorders and cancer in children.

How is radioactive iodine treatment performed?

Radioactive iodine treatment involves swallowing a prescribed dose of radioactive iodine in a capsule or liquid form. The thyroid efficiently absorbs and concentrates iodine from foods that contain iodine, such as iodized salt, as well as radioactive iodine. Once in the thyroid, radioactive iodine destroys thyroid tissue and thyroid cancer cells.

Will I feel pain?

Your comfort is important to both you and your care team. Radioactive iodine treatment is not painful. Some people have temporary side effects. They can include neck tenderness or pain, dry mouth, nausea, dry eyes, and swollen, sore salivary glands. Tell your doctor if you have side effects.

What are the risks and potential complications of radioactive iodine treatment?

Risks and potential complications of radioactive iodine treatment include:

  • Loss of taste and dry mouth
  • Low sperm counts or infertility in men
  • Temporary ovary dysfunction and irregular periods in women
  • Slight increased risk of developing leukemia (rare)

How do I prepare for my radioactive iodine treatment?

You are a very important member of your own healthcare team. The steps you take before your treatment can improve your safety and comfort, and help your doctor obtain the best results.

You can prepare for a radioactive iodine treatment by:

  • Abstaining from sex or using effective birth control to avoid pregnancy before and for up to a year after treatment 
  • Answering all questions about your medical history, allergies, and medications. This includes any possible allergy to iodine or shellfish, and your prescriptions, over-the-counter drugs, herbal treatments, and vitamins. It is a good idea to carry a current list of your medical conditions, medications, and allergies at all times.
  • Following your doctor’s instructions for taking or stopping your medications
  • Telling your doctor if there is any possibility of pregnancy or if you are breastfeeding. Stop breastfeeding before radioactive iodine begins as directed by your doctor.