Iodine I-131
Iodine I-131 is a radioactive form of iodine used primarily to treat thyroid conditions, including hyperthyroidism and certain types of thyroid cancer. The thyroid gland naturally absorbs iodine, allowing the radioactive isotope to selectively target and destroy overactive or malignant thyroid cells through localized radiation exposure.
Iodine I-131 is a radiopharmaceutical that targets thyroid tissue to treat hyperthyroidism and thyroid cancer through radiation.
Key facts at a glance
- RxNorm
- 1546394
- Generic
- Iodine I-131
- Class
- pin-variant
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Primarily used to treat hyperthyroidism (including Graves' disease and toxic nodular goiter) and differentiated thyroid cancer, including ablation of residual thyroid tissue after surgery and treatment of metastatic disease.
As an isotope of iodine, I-131 is taken up by thyroid follicular cells through the sodium-iodide symporter. Once absorbed, it emits beta radiation that destroys thyroid cells locally, reducing hormone production or eliminating malignant cells.
Requires radiation safety precautions including temporary isolation from pregnant women and children. Contraindicated in pregnancy and breastfeeding. Common side effects include radiation thyroiditis, xerostomia, and risk of hypothyroidism. Patients should follow specific radiation safety guidelines provided by their healthcare team.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 28, 2026. · Read our editorial policy