top of page

Therapy: Iodine-131 for Thyrotoxicosis


  • You cannot have this therapy if you are pregnant, breast feeding or attempting to fall pregnant.

  • Iodine-131 treatment has been given safely and successfully for more than 35 years and is a safe alternative to surgery.

  • You have been referred for an Iodine-131 therapy due to an overactive throid gland.

  • This overactivity has been determined either by a 99mTc Thyroid Study or various blood tests.

  • Other reasons for having this treatment may include:

    • Multinodular Goitre

    • Overactive nodule(s) in the thyroid.

  • The Iodine-131 is in a capsule form and is tasteless.

  • Once you have swallowed the capsule, you will be asked to immediately have something to eat and drink.

  • This breaks down the capsule in the stomach and allows rapid absorption of the Iodine-131.

  • The Iodine-131 destroys the functioning thyroid tissue by releasing radiation (electrons or beta particles) and may cause the thyroid to become under-active.

  • You will need to have your thyroid function tested by your doctor and if it falls below normal, you will need to take replacement thyroid hormone (usually for life).

  • Normally, only one Iodine-131 capsule is enough to treat your thyroid but occasionally a second capsule is required.

  • You should not have this treatment if you are pregnant.

  • Breast-feeding should be stopped completely.

  • If you are planning further children, this should be postponed for at least 6 months 'after' the Iodine-131 treatment. This is relevant to males and females. 

  • It has been noted that for a period of 12 weeks, some airport and security alarms may be triggered off by the slight radiation you will be giving off. If you choose to travel overseas during this period, you should have with you the documentation that will be given to you on the day of therapy.

  • The thyroid takes up most of the Iodine-131 and the remainder is excreted in the saliva, urine and bowels.

  • By having this treatment, you will be slightly radioactive for a short period of time.

  • You receive a radiation dose by having an Iodine-131 therapy but the benefits from this treatment far outweigh any radiation risks.

  • Note: ​For people who have difficulty swallowing capsules, there is a liquid alternative and this information should be conveyed to your doctor.

Some simple precautions should be followed:

  • For the first THREE days:

    • Use separate eating utensils.

    • No lip kisses.

    • No sexual intercourse.

    • Need to sleep alone.

    • Do not undertake long trips on planes or other public transport.

    • Do not attend the cinema.

    • If you have young children in your house, have them stay elsewhere with relatives if possible.

    • Double flush the toilet and wash your hands well.

  • For the first WEEK:

    • Spend as little time as possible close up to people.

    • When in the same room, step back a meter or two (since the radiation is absorbed in air).


Patient Preparation:

  • You can not be pregnant, trying to fall pregnant or breast feeding to have this treatment.

  • If you are of child-bearing age, we require a beta-HCG blood test stating you are not pregnant before we can proceed with the treatment. This should be undertaken less than three days prior the therapy.

  • If you are taking Neo-Mercazole (Carbimazole) or Propylthiouracil (PTU), you need to stop these one week prior treatment.

  • A low Iodine diet is ideal for 2 weeks prior your test i.e. Avoid: Seaweed and Kelp products, Agar, Carrageen, Sushi, Seafood, Multivitamins, Skin products with Iodine, Iodized Salt, Milk/Dairy products, Eggs, FDC Red dye #3, Chocolate, Commercial Bread with Iodine, cough syrups, etc...

  • Investigations with Iodine contrast media should be avoided for at least 8 weeks prior your treatment.

  • Amiodarone can effect the treatment of your thyroid for up to 2 years after cessation. Please seek advise from your doctor or call us to discuss.

  • If you have had prior imaging e.g. PET, Nuclear Scan, CT, MRI, X-Ray, Ultrasound, etc... please bring these with you.

  • Please also bring your referral and any blood results that you may have had done.

  • Bring a list of any medications you are taking.



Breast-Feeding Mothers: Once you have been given the tracer, you need to stop breast-feeding completely.

value. quality care. convenience.

bottom of page