When should potassium iodide be administered for it to be most effective?

Potassium iodide is most effective when administered before exposure to radioactive iodine. This is because the compound works by saturating the thyroid gland with stable iodine, thereby preventing the absorption of radioactive iodine. If taken beforehand, potassium iodide helps block the uptake of radioactive iodine and reduces the risk of thyroid cancer and other thyroid-related diseases that can result from radiation exposure.

When potassium iodide is taken immediately after exposure, its effectiveness diminishes significantly. If symptoms of radiation sickness appear, it is typically too late to provide preventive benefits against thyroid absorption of radioactive iodine. Additionally, routine supplementation is not a practical or effective use of potassium iodide, as it is intended for specific emergency situations rather than long-term consumption. Thus, the most effective time to administer potassium iodide is indeed before any potential exposure to radioactive iodine.