Is radioactive iodine therapy done with radioactive iodine (I-131)?

I-131 is a radioactive form of iodine. Thyroid cells naturally take up iodine, so I-131 can concentrate in thyroid tissue after it is swallowed, usually as a capsule or liquid. The radiation released by I-131 treats the targeted tissue from within the body.

The treatment is used in selected thyroid conditions, including some thyroid cancers and an overactive thyroid. Its suitability depends on the diagnosis, thyroid function, scans, previous treatment and overall health. Because the material remains radioactive for a period, the team gives personalised instructions about distance, hygiene and contact with others.

Ask whether you need to change thyroid medicines or follow a low-iodine preparation plan. Tell the team if you are pregnant, trying to become pregnant, breastfeeding, taking medicines or have difficulty swallowing. After treatment, follow instructions about drinking fluids, bathroom hygiene, sleeping arrangements and contact with children or pregnant people.

Keep follow-up appointments so the team can assess thyroid function and response. Do not stop or restart medicines unless the treating team gives you a plan.

Contact the treatment team for persistent vomiting, difficulty swallowing, neck swelling, severe neck pain, palpitations or symptoms of very low or very high thyroid activity. Seek urgent care for breathing difficulty, collapse or rapidly worsening swelling.

Why is I-131 appropriate for my condition? How should I prepare? How long will precautions last for me? Which medicines must change? What symptoms require urgent advice, and when will thyroid blood tests be checked?