Before Your RAI Treament

Diagnostic Whole-Body Scan

This scan is used to determine if there are remaining thyroid cells or cancer cells to be destroyed post surgery. The scan also helps your doctor determine the dose of radioactive iodine to give you.

Thyroid HormoneReplacement

Receptivity to Radioactive Iodine

Your doctor will raise your level of thyroid-stimulating hormone by either stopping your Thyroid Hormone Replacement therapy or giving you recombinant thyroid-stimulating hormone injections. If your thyroid hormone replacement therapy is stopped, you may temporarily experience symptoms of hypothyroidism (fatigue for example).

Low-Iodine Diet

To make thyroid cells more receptive to radioactive iodine, you will be asked to follow a low iodine diet for approximately 2 weeks before treatment and 1 to 2 days afterward. A diet of less than 50 micrograms of iodine per day is recommended and involves avoiding high-iodine foods, such as iodized salt, fish, red dye #3, and dairy products. Your doctor may have specific recommendations for a low-iodine diet.

Dental Care

The radiation in radioactive iodine can affect your dental health if it causes a reduction in saliva, so you should make sure your teeth and gums are in the best possible condition at the time of treatment. Schedule a cleaning and tell your dentist that you will be receiving radioactive iodine.

Anti-nausea Medication

Nausea can be a common side effect of receiving radioactive iodine, but it can be prevented with medication your doctor may prescribe beforehand. Talk to your doctor about receiving anti-nausea medication.


Radioactive iodine should not be used if you are breastfeeding or nursing. Talk to your doctor about your specific situation.

On Your RAI Treatment Day

Check with Your Doctor

Follow your doctor’s instructions on what you can eat or drink, including medications.

What to Pack

Photo ID and health insurance information

Foods such as sugarless gum, lemons, sour candies, etc, to ease dry mouth

Water or other drinks to stay hydrated and to pass RAI through your urine

Personal medication as directed by your doctor

Reading material you can leave behind.

Avoid Unessential Items

Do not bring unessential items with you such as additional clothes to wear, jewelry, watches, books, or your phone because they could become contaminated with radioactivity and would be discarded. Make sure you follow the instructions of your institution.

Receiving Treatment

You will take Radioactive Iodine I-131 by mouth in either liquid or capsule form. 95% of patients receive a capsule which does not taste anything. The liquid may taste metallic.

Hospital Admittance

Depending on the dose you are given and other factors, you may be treated as an outpatient and sent home OR admitted to the hospital to be kept in isolation for a period ranging from a few hours to one or more days.

Isolation Due to Radioactivity

If hospitalized, you will remain in your hospital room and will be unable to receive visitors until it is safe to release you from isolation. If you are sent home immediately following your treatment, follow your doctor’s instructions carefully. You will have to limit contact until most of the radioactivity is gone. 80% of the dose is eliminated within 48 hours provided you drink a lot.

What to Expect After Receiving RAI Treatment

The First 24 Hours

If you are sent home immediately following your treatment, follow your doctor’s instructions carefully. Follow instructions on maintaining a low-iodine diet and drinking fluids to stay hydrated to help pass the remaining radioactive iodine through your urine.

Days After Treatment

Follow your doctor’s instructions on avoiding close contact with people in the days following I-131 treatment. The length of the isolation period will depend on whether you have small children at home, encounter pregnant woman, and other factors.

Limiting Exposure at Home

Sleep alone (or at least 6 feet away from your partner) for several days.

Use separate bath linens and wash these and underclothing separately for 1 week.

Use separate eating utensils or disposable eating utensils; wash utensils separately for 1 week.

Do not prepare food for others.

Rinse the sink and tub thoroughly after using them; shower every day to help remove the radiation through perspiration.

Wash your hands with soap and plenty of water every time you use the toilet; flush the toilet each time you use it and wash the toilet seat.

Diet and Intake

In 1 to 2 days after receiving radioactive iodine, you will begin taking thyroid hormone pills and remain on a low-iodine diet. You may be advised to take laxatives in order to reduce the amount of radiation exposure in your in your intestinal tract.


Discuss with your doctor how long you should wait before attempting to become pregnant after your treatment (experts suggest 3-6 months for males and 6 to 12 months for females).


Traveling is possible. Every situation is different. If you need to travel by plane or other public transportation, carry an information card or letter of explanation that you have received radioactive iodine treatment from your doctor for at least 3 months after treatment.

At Home Dental Care

Radioactive iodine changes the amount of your saliva, so follow-up care with your dentist is important. If you notice a change in taste or saliva, use toothpaste and mouthwash without alcohol, phenol, or whitening agents. Baking soda is a good option for dental care and may be used 4 to 5 times daily. Floss daily. Do not share toothbrush.


Post-therapy Scan

Within 2 to 7 days after RAI therapy, a whole-body scan will be taken. This scan will provide baseline information and will be compared to future scans to assess disease status. These scans are useful to determine follow-up and additional treatment if necessary.