Facts vs Fiction about RAI

While radioactive iodine (RAI) has been used successfully for many decades in the treatment of thyroid cancer (except medullary and anaplastic), its benefits and risks are sometimes misunderstood by patients and their families. To help you avoid any confusion, we have provided some facts that dispel common misconceptions patients may have.

If you have questions or concerns about radioactive iodine, talk with your doctor.

Below are some common misconceptions about radioactive iodine:


I don’t need radioactive iodine (Iodine-131) because I had all of my thyroid removed ”

Surgery may not remove 100% of thyroid cells.

Surgeons leave behind some thyroid tissue to minimize the risk of nerve damage affecting your voice box or damage to your parathyroid glands. Radioactive iodine removes those remaining cells which may be cancerous.

In some cases, it is possible that thyroid cancer has already spread beyond the thyroid gland to lymph nodes or other parts of the body. Radioactive iodine will destroy thyroid cancer cells regardless of their location.

Risk of radiation exposure or contamination from your body depends on your biology, the amount of radioactive iodine you were given (the dose), and how much thyroid tissue remains in your body after surgery.

Radiation exposure from radioactive iodine is limited only to when iodine-131 is in the body. 80% or more is usually eliminated from your body within 48 hours.

Your doctor will advise you to take certain precautions to avoid radiation exposure (in various circumstances) to others for several days after therapy (typically 1 to 5 days).

Everyone is different; talk to your doctor about your specific situation.


I’ll be radioactive afterward ”


I will lose my hair ”

Radioactive iodine does not cause hair loss.

Radioactive iodine is generally well tolerated.

Most side effects, if any, last for a short time, resolve themselves, and are very manageable.

Common side effects include:

  • Nausea and upset stomach (your doctor can prescribe medication to reduce the chance of this)
  • Possible reduction in the production of saliva
  • Temporary taste changes

There have been reports of secondary malignancy (leukemia) in very rare cases - 1 person in 10,000 treated may develop.


The side effects of radioactive iodine (Iodine-131) are horrible ”


I don’t need radioactive iodine (iodine-131) because my doctor says I have a low risk of my thyroid cancer coming back ”

Doctors don’t agree on how to treat low-risk patients because it is not known who may or may not benefit from radioactive iodine

Ask your doctor about the benefits and risks of radioactive iodine for your specific situation

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I won’t be able to have kids ”

Medical experts believe that the likelihood of infertility or birth defects in children following radioiodine therapy is no different from the general population.

Medical experts also generally recommend that women should wait 6-12 months before becoming pregnant and men should wait 3-6 months before conceiving after receiving radioactive iodine.


The radiation from radioactive iodine (iodine-131) will be harmful to my body ”

As with any medication, there are risks of side effects, which your doctor can explain to you.

Treatment with radioactive iodine is a targeted therapy because of how iodine is taken up by thyroid cells, minimizing the risk of harm to other parts of your body.

It is extremely rare that radioactive iodine is linked to the development of other cancers (1 in 10,000 treated).