Pharmacy Services

Potassium Iodide

March 16, 2011

The earthquake in Japan on March 11 resulted in widely-publicized radiation emergencies at several Japanese nuclear power plants. In response to the extensive media coverage, patients in the US may be asking healthcare providers about obtaining potassium iodide for prophylactic use in the event of radiation exposure.

Potassium iodide is administered prophylactically after radiation exposure to reduce radiation uptake by the thyroid gland, reducing the risk of thyroid cancer and other radiation-related thyroid illnesses. The drug is FDA-approved and is available as an over-the-counter medication. Potassium iodide is not intended for continued use and is most effective when taken within 3 – 4 hours after radiation exposure. A single dose protects the thyroid gland for 24 – 48 hours, giving exposed individuals time to evacuate the exposed area or seek shelter from further radiation. Because it does not protect other parts of the body from the adverse effects of radiation, potassium iodide is not intended for use as a sole protective measure (in the absence of evacuation or shelter).

The Nuclear Regulatory Commission (NRC) develops guidelines for prevention and management of radiologic emergencies. The NRC currently requires states to have an emergency supply of potassium iodide available for members of the public who reside within 10 miles of a nuclear power plant, to be used in the event of a nuclear accident. However, the recent incidents in Japan are thousands of miles away from the US, across the Pacific Ocean. The NRC states that potassium iodide prophylaxis for these events is unnecessary for anyone currently in the US (including Hawaii, Alaska, the West Coast, and Utah), but may be necessary for US citizens in Japan. Those currently in the US are unlikely to be exposed to harmful radiation as a result of the Japanese nuclear incidents.

Educate patients about the appropriate prophylactic use of potassium iodide. Advise patients against purchasing potassium iodide if they do not belong to an at-risk population (eg, live within 10 miles of nuclear power plant). Additional resources are available at the following links:

March 16, 2011; University of Utah, Drug Information Service. Copyright 2011, Drug Information Service, University of Utah, Salt Lake City, UT.