Potassium Iodine – A protective measure not a magic pill

One of the protective measures that communities around nuclear power plants might use in the case of a radiological emergency is potassium iodine. But potassium iodine, often just called by its chemical symbol, KI, can be confusing for the public — exactly what does it do and when should it be taken?

So here are some facts about KI:

  • It is not an “anti radiation” pill. Potassium iodide is a salt, similar to table salt. It is routinely added to table salt to make it “iodized.” Potassium iodide, if taken within the appropriate time and at the appropriate dosage prevents the thyroid gland from taking in radioactive iodine. This can help to reduce the risk from thyroid disease, including cancer as a result of a severe reactor accident. KI doesn’t protect the thyroid gland from any other radioactive element nor does it protect the thyroid or the whole body from external exposure to radiation. Its use is very limited.
  • KI comes as a tablet, either in 65 mg or 130 mg strengths. The usual dose for a child is 65 mg, however, it is very important that the FDA dosing guidelines be followed for small children as too much stable iodine can also be harmful to them. The tablet can be easily crushed and mixed with liquid to make it easier to swallow.
  • It is important that KI not be taken unless directed by appropriate state or local authorities during the emergency and then, it should be taken in accordance with those directions.
  • KI is NOT the same thing as table salt, and table salt should never be ingested as a substitute.
  • The NRC provides KI – free of charge — to states that have requested it for their population within the 10-mile emergency planning zone of a nuclear power plant. Some states have distributed KI to residents of a plant’s emergency planning zone. In other states, KI is stockpiled and would be distributed if and when it is necessary.
  • In the event of a serious nuclear incident, KI could be used in addition to evacuation or sheltering in place in accordance with directions from responsible state/local officials. For more information, see Consideration of Potassium Iodide in Emergency Planning.

The FDA’s Frequently Asked Questions on KI is a very good resource if you want more information.

Patricia Milligan
Senior Level Advisor

Author: Moderator

Public Affairs Officer for the U.S. Nuclear Regulatory Commission

3 thoughts on “Potassium Iodine – A protective measure not a magic pill”

  1. It is very important that the FDA dosing guidelines be followed for small children as too much stable iodine can also be harmful to them. thanks for this useful informtion.

  2. wonderful information, I had come to know about your blog from my friend, and let me tell you, your website gives the best and the most interesting information. This is just the kind of information that i had been looking for, i’m already your rss reader now and i would regularly watch out for the new posts, once again hats off to you!
    Thanks & regards

  3. As I’ve stated publicly, many times: “Friends don’t let Friends take KI.”

    Only take such medication at the direction of medical or emergency personnel.

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