Watching coverage of the Japan nuclear meltdown over the last couple of days — as well as the related discussion of the risk of nuclear plant meltdown here in the United States — the distribution of potassium iodide there made me wonder:

  • What does potassium iodide (KI) do, exactly?
  • Can a person buy potassium iodide tablets without a prescription?
  • Would it make any sense to keep potassium iodide tablets on hand in case of a nuclear plant meltdown closer to home?

By the way, it is potassium iodide that authorities are distributing. In pure form, it is white. Over time, potassium iodide can oxidize, which turns it into the more yellow iodine. Potassium iodide may also be administered as a “saturated solution of potassium iodide” (SSKI).

I found a couple of very helpful fact sheets from the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration:

In short, after a radiological or nuclear event, radioactive iodine may be released into the air and eventually get into a person’s body through breathing, eating, or drinking. Radioactive iodine absorbed by the thyroid can then injure the thyroid gland. Because non-radioactive KI acts to block radioactive iodine from being taken into the thyroid gland, it can help protect this gland from injury and reduce your risk of thyroid cancer.

Having tablets on hand could make sense, because KI works best if used within 3-4 hours of exposure. Infants and children are at the greatest risk, as well as pregnant and nursing females. Anyone over 40 is at the least risk.

Please read both pages linked above for more complete details.

Potassium iodide can be bought without a prescription. The FDA has approved Iosat, ThyroSafe, and ThyroShield KI products.

You can order Iosat tablets online from Anbex, Inc.

As for Recipharm AB’s ThyroSafe potassium iodide, overwhelming demand for potassium iodide has temporarily shut down online ordering at last check.

ThyroShield is a potassium iodide oral solution from Fleming & Company, Pharmaceuticals. It’s available though pharmacists, or online via

Nukepills also sells black raspberry-flavored Thyro Shield Potassium Iodide Oral Solution at