Potassium Iodide

What It Is, How It Works, Side Effects & Dosages


Your body requires various nutrients, vitamins, minerals, and chemicals, to function properly and efficiently. Iodine is one such chemical which is essential for the proper functioning of your thyroid. Potassium Iodide, the potassium salt of iodine, also known as KI (K for Potassium and I for Iodine), is a safe source of iodine which offers superior absorption and purity over other sources of iodine such as kelp (seaweed), seafood and iodized salt.

Available in the forms of pills, tablets, capsules, and solutions, KI is an important source of necessary Iodine which offers a range of therapeutic and medicinal applications; from supporting optimal thyroid health, to controlling hyperthyroidism, to offering protection against radioactive iodine (Iodine-131) fallout.

What Is Potassium Iodide?

Potassium Iodide is a salt formed by the combination and chemical bonding of potassium with stable iodine. This non-radioactive and stable form of iodine, plays an important role in life processes and the production of thyroid hormones. Unless there is a dietary shortfall of iodine, your body derives most of its required iodine from daily food intake; however, if there is an iodine shortfall, KI can be used to cover this shortfall and provide a stable and highly-absorbed form of iodine.

Potassium Iodide Elements

How Does It Work?

Your thyroid gland, one of the most sensitive organs in your body, plays an important role in regulating your metabolism, bodyweight and temperature. Under normal conditions, kelp (seaweed), seafood, and iodized salt, typically contain enough iodine to keep your thyroid healthy and support the optimal production of thyroxine; however, these sources do not contain enough iodine to prevent or minimize radioactive iodine from damaging your thyroid.

Because KI is preferentially absorbed over radioactive iodine, this preferential absorption may saturate your thyroid gland with stable iodine and suppress the production of thyroxine for up to 24 hours. Potassium Iodide is the only form of Iodine which may provide you with protection against radioiodine exposure.

What Is It Used For?

The most common uses and benefits of Potassium Iodide are health and wellbeing related; in particular, KI may:

  • protect your thyroid by preventing the uptake of radioiodine (Iodine-131) during nuclear accidents, fallout and emergencies
  • control hyperthyroidism by temporarily suppressing the production of thyroxine for up to 24 hours
  • support optimal thyroid health by providing a stable, readily absorbed and superior form of iodine
  • assist patients with long-term and chronic lung problems such as asthma or emphysema, by acting as an expectorant and increasing the amount of fluid in respiratory secretions such as phlegm to break up mucus and promote its elimination through coughing
  • be used in nuclear medicine to block thyroid iodine absorption during various kinds of scanning and therapy with radio isotopes, and
  • be used in combination with anti-thyroid medication as a preparatory step for the surgical removal of the thyroid gland

Who Should Take It?

According to the Food and Drug Administration (FDA), Potassium Iodide is Generally Recognized As Safe (GRAS) for people of all age groups, and may be administered in the event of a nuclear emergency. In the event of a nuclear emergency, if there is a threat of radioactive iodine contamination:

  • infants and those who are nursing, require a recommended dosage of Potassium Iodide, as the Potassium Iodide obtained from breast milk or infant formula is too low to prevent the uptake of radioactive iodine
  • children are advised to take KI unless they are known to be allergic to iodine
  • young adults aged between 18 and 40 years are advised to take Potassium Iodide as a precautionary measure against the harmful effects of radiation, and
  • pregnant women and their newborns who are highly vulnerable to the uptake of radioiodine, since iodine, in all its forms, crosses the placenta and is excreted by breast milk, putting their baby at risk, are generally advised to take KI

Who Shouldn't Take It?

Certain medical conditions and medications may make it harmful to take Potassium Iodide supplements; particularly medications containing high levels of iodine. In general, you should always take Potassium Iodide for radiation protection under the guidance of a health care provider, and particularly so if you:

  • have a known allergy to iodine
  • have skin disorders such as Urticarial Vasculitis or Dermatitis Herpetiformis
  • are an older adult, above 40 years of age, because this is the lowest risk age group for thyroid cancer but the highest risk group for risk of allergic reactions to Potassium Iodide, or
  • suffer from a thyroid disease such as Graves' Disease and are already under treatment with Iodine

What Are the Side Effects?

Although the benefits of taking Potassium Iodide pills generally outweigh the negatives, especially in a radiation emergency, some side effects and adverse effects of KI have been observed. It is important to note that newborn infants below 1 month of age should not be given more than a single dose of Potassium Iodide, as extra doses may put them at risk for hypothyroidism in later life. These KI side effects and adverse effects may affect all age groups, and may include:

Potassium Iodide Side Effects
  • stomach pains
  • light-headedness
  • diarrhea
  • nausea
  • vomiting
  • swelling of the neck, throat, mouth or face
  • skin rash
  • chest pain
  • cardiac arrhythmia
  • shortness of breath
  • blurred vision
  • lethargy
  • tingling in hands and feet
  • sores in the mouth
  • fever
  • loss of appetite
  • inflammation of the salivary glands
  • metallic taste in mouth, and
  • specific thyroid related adverse effects

Potassium Iodide & Radiation

With the volatile and escalating nuclear situation in Fukushima, Japan, following the Earthquake and Tsunami of March 2011, and recent interest in the Nebraska Nuclear Power Plant, there has been a surge of interest in the radiation protection effects of KI. Because global radiation levels have increased significantly, many people are taking preventative measures by stockpiling Potassium Iodide tablets for the future. In addition to stockpiling KI, an added precaution would be to know what radiation is, and why Potassium Iodide is the trusted protection which may minimize its harmful effects.

What Is Radiation?

Radiation is energy emitted in the form of rays or particles which may be able to penetrate various materials. Light, radio, and microwaves, are types of radiation that are called non-ionizing; whereas unstable atoms produce ionizing radiation which is widely known to induce cancer and result in DNA mutations. An atom with an unstable nucleus is said to be radioactive and the emissions can be in the form of alpha, beta, or gamma radiation; respectively increasing in penetration power.

Radioactive fallout refers to radioactive particles, created by a nuclear explosion or a leak from a nuclear power plant, and released in the form of radioactivity and excess radiation. When an explosion or leak occurs, the radiation is sucked up into the atmosphere in the form of a cloud and then released slowly back to the surface; often carrying and spreading the radiation for many miles.

What Is Radioactive Iodine?

The radioactive isotope of particular concern is Iodine-131. This is most commonly called radioiodine, although there are a number of other isotopes of the element which are also radioactive. Iodine-131 emits beta and gamma rays and has a half life of 8 days; meaning, after 8 days, the amount of Iodine-131 reduces by 50%. Iodine-131 comprises almost three percent of radioactive fallout; however, Iodine-131 is highly enriched in the thyroid gland and can cause mutation or destruction in cells which have been exposed. Additionally, it can even affect the surrounding cells to a distance of several millimeters.

Although Iodine-131 is sometimes used in medical tests, it is a major radiation hazard from leakage of nuclear fission materials, with the long-term health effects of Iodine-131 being observed in people exposed to fallout from: the 1950's open-air atomic testing, Chernobyl, Three Mile Island and so on. Such health and side effects include: thyroid cancer, hypothyroidism and thyroid goiters.

How Does Potassium Iodide Help?

Since your thyroid gland absorbs and uses iodine to manufacture thyroid hormones, iodine is naturally absorbed quickly by your cells. When radioactive iodine is released into the atmosphere and breathed or ingested into your body, your thyroid quickly absorbs radioactive iodine just like stable iodine, as your thyroid is unable to tell the difference.

Taking KI before exposure to radioiodine or within a very short timeframe of it, may provide an alternate source of "clean" iodine which your thyroid may preferentially absorb; therefore, suppressing thyroid radioiodine uptake and potentially minimizing your risk of thyroid damage and cancer.

As a general rule for adults aged 18 years to 40 years, 130mg of Potassium Iodide may protect the thyroid gland for as much as 24 hours, provided no further exposure takes place. Since radioactive iodine can contaminate the food and water supply as well, it may be wise not to eat or drink contaminated material during such an emergency.

How Much Should Be Taken?

The FDA has given approval to two forms of Potassium Iodide supplements for oral ingestion in case of a nuclear emergency; KI tablets and KI liquid solutions. Potassium Iodide tablets are typically available in 32.5mg, 65mg, and 130mg strengths, and Potassium Iodide liquid solutions are typically available in 65mg/ml strength.

The specific dosages outlined in the daily dosage chart below should never be exceeded, and should always be administered under the guidance of a health care provider:

  • women during pregnancy or breastfeeding their infants should take 130 mg
  • adults aged 18 years to 40 years should take 130 mg
  • children aged 3 years to 18 years should take 65 mg
  • children aged 1 month to 3 years should take 32 mg
  • newborns to 1 month should take 16mg
Potassium Iodide Dosages

What Won't It Do?

In the midst of all the positive information about Potassium Iodide, it is important to remember that KI may only protect your thyroid, and cannot prevent either the absorption of radiation, or the damage caused by radiation to other organs throughout your body.

KI may suppress thyroid radioiodine uptake by saturating your thyroid with stable iodine, but is not able to reverse or cure any damage already caused by prior absorption of radioactive iodine. Potassium Iodide supplements cannot, and will not, protect your body from other radioactive elements, and is it neither effective against other types of radiation poisoning and contamination.


Since 1982, the FDA has continued its approval of Potassium Iodide to offer maximum protection against radioactive iodine uptake by your thyroid. Although the effects of Potassium Iodide may last as long as 24 hours, it is conceivable that radioactive iodine can remain in the atmosphere for much longer.

For such an eventuality, there are systems of emergency management in place which can direct the your on the best course of action to be followed. One of the most important things to remember is that although Potassium Iodide tablets are available without prescription and demonstrated to be highly effective, KI should always be dispensed under the guidance of a health care provider and the recommended dosage should never be exceeded.

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