Potassium iodide is a salt of stable (not radioactive) iodine. Stable iodine is an important chemical needed by the body to make thyroid hormones.
After a radiological or nuclear event, radioactive iodine may be released into the air and then be breathed into the lungs. There is also the potential that radioactive iodine may also contaminate local food supply, thus being able to enter the body through food or drink.
When radioactive iodine enters one’s body the thyroid gland can quickly absorb the chemical. Radioactive iodine absorbed by the thyroid can then injure the gland. Non-radioactive potassium iodide acts to block radioactive iodine from being taken into the thyroid gland.
After a radiologic or nuclear event, local public health or emergency management officials will tell the public if potassium iodide or other protective actions are needed (wearing a face mask, remaining where you are, evacuating, not consuming certain items, etc.)
Following authorities’ instructions may lower the amount of radioactive iodine that enters your body and lower the risk of serious injury to your thyroid gland.