by Kohnle D
(Radioiodine Treatment)


Radioactive iodine treatment is used to treat certain thyroid diseases. The procedure uses a radioactive form of iodine. Iodine is normally taken up by the thyroid gland. This radioactive iodine destroys cells in the thyroid. The radioactivity will have little affect on other parts of the body.

The Thyroid Gland
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Reasons for Procedure

Radioactive iodine may be done to treat:

Possible Complications

Radioactive iodine therapy may cause:

  • Inflammation of the salivary glands causing painful cheeks and dry mouth
  • Metallic taste in the mouth
  • Dry mouth
  • Sore throat
  • Neck pain
  • Nausea or vomiting
  • Fatigue
  • Flushing
  • Tightness in throat
  • High or low thyroid hormone levels

The procedure may be harmful to a fetus. It is not recommended for pregnant women. Nursing mothers should stop breastfeeding for at least a week after the procedure.

What to Expect

Prior to Procedure

Preparation for the surgery may include:

  • A special low iodine diet.
  • Changes in current medicine. The doctor needs to know about any current medicine. Some thyroid hormone medicine should be stopped up to 4 weeks before the procedure. Hyperthyroid medicine may also need to be stopped at least 5 to 7 days before the procedure.
  • Food and most drinks may need to be avoided a few hours before. Water may be allowed.
  • A thyroid uptake and scan may be done before the treatment.

A pregnancy test will be done in women of childbearing age.

Description of the Procedure

The doctor will give radioactive iodine as pills or liquids. The thyroid will naturally absorb the iodine. It will pass out of the body through the urine.

How Long Will It Take?

At least an hour

Will It Hurt?

The treatment is painless.

Postoperative Care

The body can give off radiation for a few days. It can effect health of others that are nearby. A few days stay in the hospital may be needed. Other care will be needed at home including keeping distance from others.

Thyroid levels return to normal within 8 to 12 weeks for most who have treatment for hyperthyroidism. A second dose of radioactive iodine treatment is needed for some.

Radioactive iodine treatment can cause hypothyroidism (low thyroid hormones). It may be temporary or permanent. Thyroid levels will be checked every few months until levels are stable.

Call Your Doctor

Call your doctor if any of these occur:

  • Signs of infection, such as fever and chills
  • Nausea or vomiting
  • Excessive fatigue
  • Worsening pain or swelling in the neck
  • Passing little urine
  • Tightness in throat or trouble breathing
  • Facial numbness
  • Rapid pulse

If you think you have an emergency, call for emergency medical services right away.


American Thyroid Association 

Hormone Health Network—Endocrine Society 


Health Canada 

Thyroid Foundation of Canada 


Pluijmen MJ, Eustatia-Rutten C, Goslings BM, et al. Effects of low-iodide diet on postsurgical radioiodide ablation therapy in patients with differentiated thyroid carcinoma. Clin Endocrinol (Oxf). 2003;58(4):428-435.

Radioactive Iodine (Radioiodine) Therapy for Thyroid Cancer. American Cancer Society website. Available at: Updated March 14, 2019. Accessed March 18, 2020.

Radioactive iodine for hyperthyroidism. Endocrine Society Hormone Health Network website. Available at: Accessed March 18, 2020.

Radioiodine (I-131) therapy. Radiological Society of North America Radiology Info website. Available at: Updated March 17, 2016. Accessed March 18, 2020.

Rivkees SA, Dinauer C. An optimal treatment for pediatric Graves’ disease is radioiodine. J Clin Endocrinol Metab. 2007;92(3):797-800.

Revision Information

  • Reviewer: EBSCO Medical Review Board James Cornell, MD
  • Review Date: 11/2019
  • Update Date: 03/18/2020