Share this page

Health Library

Radioactive Iodine Treatment(Radioiodine Treatment)

Pronounced: RAY-dee-oh-AK-tiv I-oh-dine


Radioactive iodine treatment is used to treat certain thyroid diseases and thyroid cancer. The procedure is done with a radioactive form of the element iodine. Radioactive iodine is taken up by the thyroid gland. There it treats thyroid disease by destroying the cells. The radioactivity is not spread to other parts of the body.

The Thyroid Gland

Copyright © Nucleus Medical Media, Inc.

Reasons for Procedure

It may be done to treat:

Possible Complications

Possible side effects and complications of radioactive iodine therapy include:

  • Inflammation of the salivary glands causing painful cheeks and dry mouth
  • Metallic taste in the mouth
  • Dry mouth
  • Sore throat
  • Pain in the neck
  • Nausea or vomiting
  • Fatigue
  • Flushing
  • Tightness in throat
  • Abnormally high or abnormally low thyroid hormone levels

Pregnant women are at an increased risk of complications. The procedure may be harmful to the fetus. It should not be done in pregnant women. Nursing mothers should stop breastfeeding for at least a week after the procedure.

What to Expect
Prior to Procedure
  • If advised by your doctor, eat a special diet. Your doctor may want you on a special low iodine diet prior to the procedure. This may help your procedure to be more successful.
  • Talk to your doctor about your medications. Some thyroid hormone medicine should be discontinued up to 4 weeks before the procedure. Other medications used to treat hyperthyroidism should be discontinued 5-7 days before the procedure.
  • For 2 hours before the procedure, do not eat or drink anything. Water may be allowed.
  • If you are a woman of childbearing age, the doctor will do a pregnancy test.
  • A thyroid uptake and scan may be done before the treatment.
Description of the Procedure

You will be given some tablets or liquids that contain radioactive iodine. You will swallow the tablets. The iodine will be naturally taken up by the thyroid.

How Long Will It Take?

At least an hour

Will It Hurt?

The treatment is painless.

Postoperative Care

Any radioactive iodine that is not taken up directly by the thyroid will be passed through the urine. Be sure to follow your doctor's instructions. This may include:

  • Do not eat any solid foods for at least 2 hours after treatment. Drink a lot of clear liquids, such as water or juice.
  • For the first 8-12 hours following treatment, use the bathroom every hour. This will help flush the excess iodine from your body.
  • Limit your contact with others. Do not enter a room with any infants or children. Stay at least 3 feet away from other adults. Do not stay near any other adult for more than a few minutes. Do not share a bed with anyone for 48 hours following the treatment.
  • Do not share any food, drink, or dishes with anyone for the first week. Do not allow your saliva to come into contact with anyone. Avoid kissing and sexual contact.
  • Flush the toilet twice after use.
  • Wash hands often and thoroughly.
  • Resume normal thyroid medications 48 hours after the treatment.

The majority of people who undergo the treatment for hyperthyroidism will have their thyroid levels return to normal within 8-12 weeks. However, in a small number of people, a second dose of radioactive iodine treatment is needed.

A follow-up visit with your doctor will be scheduled 4-6 weeks after treatment. Radioactive active iodine treatment can cause hypothyroidism (low thyroid function). This can occur at any time after treatment. It may be temporary or permanent. Your doctor will need to check your thyroid status every few months until levels are stable.

Call Your Doctor

Call your doctor if any of these occur:

  • You have fever or chills
  • Nausea or vomiting
  • Excessive fatigue
  • Worsening pain or swelling in the neck
  • You are not urinating even with adequate fluid intake
  • Tightness in throat or trouble breathing
  • Numbness in your face
  • Rapid pulse

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


Endocrine Society

Hormone Health Network


Health Canada

Thyroid Foundation of Canada


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 for hyperthyroidism. The Endocrine Society Hormone Health Network website. Available at: Accessed December 16, 2014.

Radioiodine (I-131) therapy. Radiological Society of North America Radiology Info website. Available at: Updated February 12, 2014. Accessed December 16, 2014.

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

Last reviewed December 2014 by Kim A. Carmichael, MD, FACP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Baptist Flame

Baptist Health Systems


Find A Doctor



Baptist Medical Clinic

Patients & Visitors


Contact Us

Physician Tools

Careers at Baptist

Employee Links

Online Services

At Baptist Health Systems

At Baptist Medical Center

close ×