Potassium iodide is in the news. Here’s what it’s all about.

Can potassium iodide protect the thyroid from nuclear fallout?
March 16, 2022
woman looking at a box of potassium iodide pills in wonder.
There’s a run on potassium iodide in the United States as people fear radioactive fallout from Russian President Vladimir Putin’s war in Ukraine. Photo: Getty Images.

One might fairly compare the current run on potassium iodide – a nonprescription delivery vehicle for large doses of dietary iodine – with that of toilet paper early in the coronavirus pandemic. While the two have rather different ends, the motivation of the purchasers is the same: stocking up in case of emergency.

An emergency involving potassium iodide would be a serious one: radioactive fallout from a nuclear accident or explosion. Russian President Vladimir Putin’s war in Ukraine, with its prosecution by a nuclear power and its involvement of Ukrainian nuclear power plants (including the decommissioned, infamous Chernobyl reactor that melted down in 1986), has raised the risk of nuclear radiation release, intentional or otherwise. Hence the spiking interest in potassium iodide.

What is iodine?

It’s a trace soil mineral and micronutrient important for proper thyroid function. It’s found in seafood, seaweed dairy, eggs, chicken, and beef liver. Iodine is added as a supplement in infant formula and table salt (hence “iodized salt”).  The National Institutes of Health recommends 150 micrograms a day for adults, 220 micrograms a day for pregnant women, and 290 micrograms a day for breastfeeding women.

What happens if I don’t get enough dietary iodine?

The thyroid gland needs iodine to produce thyroid hormones, and thyroid acts as a bodily magnet for the mineral. Too little iodine risks hypothyroidism among those consuming less than 10 or 20 micrograms a day. This throttling of thyroid hormones can affect growth and development in fetuses and children, impair cognition, sap energy, and lead to goiter. Thanks to the U.S. introduction of iodized salt in the 1920s, iodine deficiency is now rare in the United States.

What is potassium iodide (or potassium iodate)?

Potassium iodide (KI) and potassium iodate (KIO3) come in tablets or liquid form. These iodine tablets and liquids deliver large doses of iodine (65 milligrams or 130 milligrams, so 400 to 800 times the adult daily recommended allowance). Fallout after a nuclear accident or detonation can spread radioactive iodine (radioiodine). A thyroid gland in need of iodine will sweep radioactive iodine up, and that can cause thyroid cancer and other thyroid damage. Potassium iodine or potassium iodate, so-called “thyroid blockers,” saturate the thyroid with nonradioactive iodine and prevent radioactive iodine uptake.

The dose depends on age and is taken once every 24 hours while radiation exposure persists. The U.S. Food and Drug Administration says potassium iodide works best if taken within 3-4 hours of exposure.

Do iodine tablets block bodily radiation in general?

No. They only protect the thyroid gland. Iodine tablets won’t help with radiation poisoning or consequences of radiation exposure not having to do with radioiodine in the thyroid gland.

In case of nuclear/radiation emergency, should everyone take iodine tablets?

The goal of potassium iodide and potassium iodate is to prevent long-term thyroid problems and cancers, so potassium iodide tablets and liquids are most important for infants, children, young adults, and pregnant and breastfeeding women, according to the CDC. The CDC advises adults over age 40 against taking iodine tablets unless “a very large dose of radioactive iodine is expected,” because that cohort has “the lowest chance of developing thyroid cancer or thyroid injury after contamination with radioactive iodine.”

Should I take potassium iodide/potassium iodate as a precaution?

No. According to the U.S. Centers for Disease Control and Prevention: “People should take KI (potassium iodide) only on the advice of public health or emergency management officials. There are health risks associated with taking KI.”

What sorts of health risks are we talking about?

According to the CDC, side effects can include stomach or gastrointestinal upset, allergic reactions, rashes, and inflammation of the salivary glands.

I’ve heard of radioiodine therapy as a treatment for thyroid cancer. True?

Yes. Radioactive iodine therapy using I-131 is a way to harness the thyroid’s thirst for iodine to kill thyroid cancer cells.

Is it possible to have an iodine allergy?

The research suggests not.

Do I need to stock up on iodine tablets?

Let’s hope not. But they’re typically available at online drugstores, Amazon, and elsewhere.

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