What Are the Uses of Potassium Iodide?

by Lucy Bell-Young

Potassium iodide (KI) is a white crystalline solid that is formed by reacting elemental iodine (I) with potassium hydroxide (KOH). It is a versatile compound that is used in a variety of industries as a supplement, an expectorant and even as a protection against radiological emergencies.  

Medical Uses of Potassium Iodide

Potassium iodide is well-suited to a range of medical applications. This is because it contains iodine, a vital nutrient for the body. There are two main areas that KI is used to target: the thyroid gland and the airways.


Potassium iodide is used as an expectorant for those who suffer from chronic breathing disorders like asthma, bronchitis and emphysema. It works by loosening the secretion of sputum that accumulates in the lungs. The mucus can then move through the air passages and be easily coughed up.

Nutritional Supplement

Iodine is a crucial nutrient that the body gets from our diet – foods like fish and sea vegetables, for example, are rich in iodine. The body needs iodine in order to produce thyroid hormones, which are vital in how we function. Thyroid hormones:

  • Control the body’s metabolism
  • Promote adrenal health
  • Help to prevent cell mutation
  • Influence feelings of emotional wellbeing
  • Help immune functions
  • Promote proper bone and brain development during pregnancy

But iodine deficiency is becoming an increasing problem. Many factors contribute to this, including a rise in sea pollution, poor diets and thyroid disorders. By containing iodine, potassium iodide is commonly used as a nutritional supplement – for humans and animals – to combat low levels of iodine.

In fact, in countries that get little seafood, a public health measure has been put in place to ensure that populations are getting enough iodine. They do this by iodising table salt with potassium iodide.

A group of people using chopsticks to pick up sushi
Potassium iodide is used to boost levels of iodine in the body. Iodine is a vital nutrient that our bodies get from food, like fish or sea vegetables.

Thyroid Medication

As we’ve just touched on, potassium iodide is great for boosting iodine levels in the body. It comes as no surprise, then, that it is most commonly used as a medical treatment for thyroid disorders.

Also known as the thyroid mineral, potassium iodide can prevent an array of thyroid-related problems, in particular: hypothyroidism and hyperthyroidism.

Hypothyroidism is a disorder that results in an extremely low activity of the thyroid gland. This means that there are not enough thyroid hormones being produced to support the body. While hypothyroidism can be caused by a number of things, iodine deficiency is a common denominator.

Potassium iodide – as well as a diet change – is sometimes used to increase iodine intake in the body. This is one way that the thyroid gland can begin producing more hormones. However, those with a thyroid disease can be very sensitive to iodine, and so it is important to always consult a doctor before taking KI as a treatment.

Hyperthyroidism is the opposite: it is when the thyroid gland is overactive, and this can result in a rapid heartbeat or an increased metabolism. In this case, potassium iodide can actually be used to shrink the size of the thyroid gland. This decreases the number of hormones being produced.

Radioactive Emergencies

Potassium iodide isn’t just used to treat medical disorders with the thyroid gland – it is also used to protect it against radioactive emergencies.

How Nuclear Disasters Affect the Thyroid

In the case of a nuclear accident, nuclear fission products are released. These tend to have excess nuclear energy, making them very unstable. This instability is also what makes them radioactive as they quickly undergo beta decay.

Iodine is the most common fission product released during a nuclear accident, and it is also one of the most dangerous. Radioactive iodine, also known as radioiodine is quickly absorbed by the thyroid gland when it’s breathed in or ingested, and this could lead to thyroid cancer.

Chernobyl Disaster

Following the 1986 nuclear disaster in Chernobyl, a saturated solution of potassium iodide was given to over 17 million people. This was an emergency measure done to prevent against any radioactive iodine that might have accumulated in civilians’ thyroid gland.

The results of using potassium iodide in this way were positive. It was observed that the levels of radioactive iodine were much lower than what would have been expected had KI not been administered. This was supported by the fact that in surrounding irradiated areas where KI was not available, epidemic levels of thyroid cancer were reported over time. This led to the FDA stating that “the data clearly demonstrates … that potassium iodide can be used [to] provide safe and effective protection against thyroid cancer caused by irradiation.”

How Does KI Protect Against Radioiodine?

Potassium iodide acts as a thyroid blocker in the case of a nuclear emergency. This means that it is able to block the thyroid from absorbing radioiodine.

It does this by saturating the thyroid gland with non-radioactive iodine. When the thyroid is fully saturated, it is unable to continue absorbing. This dramatically reduces the amount of radioactive iodine the thyroid gland will absorb and thus prevents against developing cancer.

A view from the highest apartment building in Pripyat, the town nearest Chernobyl nuclear reactor
This is a view of Pripyat, the town nearest to the Chernobyl nuclear reactor. During the Chernobyl disaster, officials in Pripyat distributed KI pills to the locals to prevent against radioiodine.


The blog on chemicals.co.uk and everything published on it is provided as an information resource only. The blog, its authors and affiliates accept no responsibility for any accident, injury or damage caused in part or directly from following the information provided on this website. We do not recommend using any chemical without first consulting the Material Safety Data Sheet which can be obtained from the manufacturer and following the safety advice and precautions on the product label. If you are in any doubt about health and safety issues please consult the Health & Safety Executive (HSE).