Skip to main content
An official website of the United States government

iodine I-131

A radioactive isotope of iodine with an atomic mass of 131, a half life of eight days, and potential antineoplastic activity. Selectively accumulating in the thyroid gland, iodine I 131 emits beta and gamma particles, thereby killing thyroid cells and decreasing thyroid hormone production.
Synonym:131-iodine
bound iodide I-131
iodide I-131
iodide, I-131
iodine 131
iodine-131
US brand name:Iodotope
Foreign brand name:Iodotrope
Abbreviation:I 131
I-131
Search NCI's Drug Dictionary