Radioactive iodine is a medicine that you take one time. After you swallow it, it is taken up by your
thyroid gland. Depending on the dosage used, the
radioactivity in the iodine destroys most or all of the tissue in your thyroid
gland, but it does not harm any other parts of your body.
Radioactive iodine treatment has been safely used on millions of people
for more than 60 years.
What To Expect After Treatment
Within a few days after treatment, the
radioactive iodine will leave your body in your urine. Drinking plenty of
fluids during this time will help your body get rid of the radioactivity. To
avoid exposing other people to radioactivity, it is important to take the
following precautions for the first 5 days after your treatment:
- Keep your distance from other people,
especially children and pregnant women.
- Do not sit next to someone
in a motor vehicle for more than 1 hour.
- Avoid close contact,
kissing, or sexual intercourse.
- Sleep alone in a separate room.
- Use separate towels,
washcloths, and sheets. Wash these and your personal clothing separately for 1
To further reduce the chance of exposing other people to
- Wash your hands with soap and lots of water
each time you use the toilet.
- Keep the toilet very clean. Men
should urinate sitting down to avoid splashing. Also, flush the toilet two or
three times after each use.
- Rinse the bathroom sink and tub
thoroughly after you use them.
- Use separate (or disposable) eating
utensils for the first few days. And wash them separately.
After you take your treatment, you may have follow-up
exams every 4 to 6 weeks until your
thyroid hormone levels return to normal.
Why It Is Done
Radioactive iodine has the best
chance of permanently curing hyperthyroidism. Doctors often use it if your
hyperthyroidism comes back after you have been treated
with antithyroid medicine. It can also be used if your hyperthyroidism comes
back after you have surgery to remove part of your thyroid gland.
How Well It Works
For most people, one dose of
radioactive iodine treatment will cure hyperthyroidism. Usually, thyroid
hormone levels return to normal in 8 to 12 weeks. In rare cases, the person
needs a second or third dose of radioactive iodine.
For some people, radioactive iodine treatment
causes the thyroid gland to become swollen and inflamed (radiation
thyroiditis). If this happens, you may feel pain in your neck. Or your
hyperthyroidism may temporarily get worse. If you get radiation thyroiditis, it
usually does not last more than a few days. And you can take medicines that
will help you feel better.
Radioactive iodine treatment may cause
hypothyroidism, which means your body makes too little
thyroid hormone. Most people will have hypothyroidism within a year
after treatment. If you have hypothyroidism, you will
need to take
thyroid hormone medicine for the rest of your life.
To learn more, see the topic
If you have
Graves' ophthalmopathy, it may get worse temporarily
after radioactive iodine therapy.
What To Think About
Most people—depending on their ages, how much thyroid hormone their bodies make, and
other health conditions they have—are treated first with radioactive
Radioactive iodine is often recommended if you have
Graves' disease and are older than 50, or if you have
thyroid nodules (toxic multinodular goiter) that are
releasing too much thyroid hormone. Radioactive iodine is not used if:
- You are
pregnant or you want to become pregnant within 6 months of
- You are breast-feeding.
- You have
thyroiditis or another kind of hyperthyroidism that is
You may take
antithyroid medicine for several weeks or months
before treatment with radioactive iodine. The antithyroid medicine will lower
thyroid hormone levels in your body and will also lower your chances of having
a more serious problem called
thyroid storm. You may also take additional medicines that can make you feel better
and help your thyroid return to normal before you are given radioactive
Radioactive iodine has been used to treat hyperthyroidism
for more than 60 years. There is no evidence that radioactive iodine causes
cancer, infertility, or birth defects.
If you have had
radioactive iodine treatment and you want to travel within a few days after
treatment, prepare for any problems you may have at airport
security. People who have had radioactive iodine treatment can set off the
radiation detection machines in airports.
If you plan to travel
within 5 to 7 days of your radioactive treatment:
- Check with local authorities about special
procedures or considerations.
- Ask your doctor to write a letter
describing the radiation isotope used, the date and time of treatment, the
dose, and its biological half-life (how long it takes for half of the
radioactive iodine to be eliminated from the body). The letter should include
your doctor's 24-hour telephone numbers so that authorities can call your
doctor if they need to verify the information in the letter.
in mind that you will have to wait for permission to travel.
Complete the special treatment information form (PDF)(What is a PDF document?) to help you understand this treatment.
|Primary Medical Reviewer||E. Gregory Thompson, MD - Internal Medicine|
|Specialist Medical Reviewer||David C.W. Lau, MD, PhD, FRCPC - Endocrinology|
|Last Revised||November 4, 2011|