The Truth about Potassium Iodide

Due to recent nuclear events in Japan, there has been an increased interest in potassium iodide supplements. Iodine is an important nutrient in the body that aids in the production of thyroid hormones. Our body gets most of the iodine it needs from the food we eat. When a nuclear event occurs, our bodies are exposed to radioactive iodine either through the contaminated air we breathe or contamination in our food supply. Once our bodies are exposed to radioactive iodine, it is quickly absorbed by the thyroid gland, which can damage the gland and ultimately lead to thyroid cancer. Potassium iodide is the medicinal form of iodine and can be taken orally to protect the thyroid gland by blocking the radioactive iodine from being absorbed.

If a nuclear event occurs and radioactive iodine is released into the environment a public health official may advise you to take one dose of potassium iodide daily for a few days. Babies and children will likely be treated first because they are more sensitive to radioactive iodine than adults and may be more likely to develop thyroid cancer from radiation exposure. One dose of potassium iodide protects the thyroid gland for 24 hours. Taking potassium iodide for too long can lead to harmful side effects such as allergic reactions, skin rashes, and thyroid problems. People with an allergy to iodine should not take this medication. People with certain skin disorders or thyroid disease (e.g. Graves’ disease) should be treated under the supervision of a doctor.

There are three over the counter potassium iodide supplements available that are approved by the Food and Drug Administration (FDA): Iosat, ThyroSafe and ThyroShield. All other potassium iodide products have not been evaluated by the FDA for consumer safety. There is a common misconception that potassium iodide will protect a person from any and all radiation exposure. However, potassium iodide only protects a person from radioactive iodine and not other forms of radiation. Thus while the thyroid gland may be protected, potassium iodide does not protect the body’s other vital organs from the harmful effects of radiation.


For more information on Potassium Iodide please visit the Centers for Disease Control and Prevention website, http://www.bt.cdc.gov/radiation/ki.asp.



Nicole Day
PharmD