Potassium Iodide

What is potassium iodide?

Potassium iodide is a salt that healthcare providers sometimes use as a medication to treat certain thyroid conditions or protect your thyroid from radiation exposure.

Potassium iodide acts as a thyroid blocker, which means it stops your thyroid from releasing thyroid hormone. This can be useful in certain situations, like if your thyroid is producing high levels of thyroid hormone (hyperthyroidism). Potassium iodide can also help protect your thyroid from absorbing radioactive iodine that accidentally enters your body.

Healthcare providers intentionally use radioactive iodine — in controlled, safe amounts — for certain imaging tests and treatments. Nuclear weapon detonations and nuclear power plant accidents release unsafe amounts of radioactive iodine (radioiodine) into the air, water and soil. Potassium iodide can protect you from such unintended environmental exposure.

Potassium iodide comes in pill (tablet) and liquid forms. Some forms require a prescription, while others you can get over the counter (OTC). You should only take potassium iodide in any form if your healthcare provider or public health officials tell you to do so. Remember that just because you can buy something over the counter doesn’t mean it’s safe or appropriate for you to take.

What conditions are treated with potassium iodide?

Healthcare providers sometimes use potassium iodide to treat:

• Hyperthyroidism, particularly when associated with Graves’ disease.
• Thyroid storm.
• Some skin conditions, including cutaneous sporotrichosis (a fungal infection).
• Iodine deficiency.

Potassium iodide is also a prescription-strength expectorant. If you have a chronic lung disease, your healthcare provider may prescribe potassium iodide to loosen mucus and make it easier for you to cough.

Potassium iodide can also help protect your thyroid:

• During radiation emergencies (like a nuclear power plant meltdown).
• During medical testing (like MIBG scans) or treatments that expose your thyroid to radiation.

Potassium iodide for radiation

Potassium iodide is best known for protecting people during a radiation emergency. But it’s important to know there are limitations. Potassium iodide only protects your thyroid from radioactive iodine (one specific radioactive material). It doesn’t protect other parts of your body, and it doesn’t protect you from all the other radioactive materials you might be exposed to that could cause radiation sickness.

Healthcare providers and public health officials only recommend using potassium iodide in certain types of radiation emergencies. These typically include nuclear power plant accidents.

Potassium iodide won’t completely protect you if a nuclear bomb goes off because the greatest threat in that situation isn’t radioactive iodine. You’d be exposed to hundreds of other types of radioactive materials, and potassium iodide has no effect on those. If a bomb goes off, don’t worry about trying to find potassium iodide. Instead, seek shelter indoors and follow local officials’ guidance.

Thyroid protection after a nuclear power plant accident

Potassium iodide can help protect your thyroid from radioactive iodine released in a nuclear power plant accident. Here’s why. Your thyroid needs iodine to function normally and produce thyroid hormone. But it doesn’t know the difference between normal iodine (like what you get from your food) and radioactive iodine. This means your thyroid grabs iodine from wherever it can.

Nuclear power plant accidents may release radioactive iodine into the nearby environment. If you breathe in contaminated air or eat contaminated food, the radioactive iodine can enter your body. Your thyroid then absorbs it. Depending on the amount that gets into your body, radioactive iodine can damage your thyroid and potentially lead to thyroid cancer down the road.

The younger you are, the more vulnerable you are to the harmful effects of radioactive iodine. Babies and children face the greatest threat. If you’re pregnant, radioactive iodine is more dangerous for you compared to other adults because your thyroid is more active during pregnancy.

That’s where potassium iodide comes into play. It fills up your thyroid with enough iodine to keep it busy for a while. So, instead of absorbing the radioactive iodine, your thyroid ignores it, and the radioactive iodine passes out of your body in your pee.

How should I use potassium iodide?

Depending on your diagnosis, your healthcare provider may prescribe potassium iodide in tablet or liquid form. Your provider or local public health officials will tell you:

• How to take potassium iodide.
• When to take it.
• The appropriate dosage.

The dosage can vary widely according to the condition you’re treating. In the context of radiation emergencies, the recommended dosage varies according to a person’s age.

How long should I take potassium iodide?

It depends on the reason you’re taking it. Follow your healthcare provider’s guidance. In radiation emergencies, one dose typically protects you for about 24 hours. So, most people should take one dose per day until local officials say it’s safe to stop taking it.

Pregnant people and newborns should only take one dose (no repeat doses) unless told otherwise. That’s because potassium iodide may impact thyroid function in fetuses and newborns.

What are the potential benefits of potassium iodide?

When used during a radiation emergency, potassium iodide can lower a person’s risk of developing thyroid cancer down the road. This is especially important in children and adults under age 40, who face a greater risk of thyroid cancer from radioactive iodine exposure.

What are the side effects of potassium iodide?

Possible side effects of potassium iodide include:

• Skin rash.
• Swollen salivary glands.
• Metallic taste in your mouth.
• Burning of your mouth and throat.
• Sore teeth and gums.
• Upset stomach, nausea and diarrhea.
• Headache.
• Head cold symptoms, like a runny nose.

Newborns who are given more than a single dose of potassium iodide run the risk of developing hypothyroidism.

Can potassium iodide cause an allergic reaction?

Potassium iodide causes an allergic reaction in some people. Signs of an allergic reaction include:

• Fever.
• Joint pain.
• Swelling of your face, lips, tongue, throat, hands or feet.
• Wheezing and/or shortness of breath.
• Difficulty speaking or swallowing.

Call a healthcare provider right away if you develop signs of an allergic reaction. Call 911 or your local emergency number if you have trouble breathing, speaking or swallowing.

Taking more potassium iodide than healthcare providers or local officials recommend can make you very sick or even be fatal. That’s why it’s crucial to follow expert advice closely when taking potassium iodide or giving it to a child.

Is taking potassium iodide safe for me?

Potassium iodide isn’t safe for everyone. It’s important to check with your healthcare provider before taking potassium iodine to make sure it’s OK for you. In general, potassium iodine may not be safe to take if you:

• Have thyroid nodules as well as heart disease.
• Are taking certain medications, including those that affect how your thyroid works.
• Are sensitive or allergic to iodine.
• Have chronic kidney (renal) failure.
• Have tuberculosis or acute bronchitis.
• Have a history of adrenal insufficiency (Addison’s disease).
• Have a weakened immune system.
• Are pregnant or breastfeeding (chestfeeding). In some situations, like radiation emergencies, the benefits of taking potassium iodide while pregnant or nursing may outweigh the risks. Follow your provider’s guidance closely.

Be sure to talk to your provider before starting potassium iodide or any other medicine. They’ll review your medical history and decide if it’s safe for you. They can tell you the benefits and risks of potassium iodide in your unique situation. They’ll also tell you if you need follow-ups or monitoring.

Is there anything I can do to make this treatment easier on me?

Your provider may recommend taking potassium iodide along with milk or juice to limit stomach upset. Talk to your provider if you’re concerned about side effects or have a history of any medication allergies.

Potassium iodide vs. iodine — what’s the difference?

Potassium iodide is a combination of two elements: potassium (K) and iodine (I). So, scientists abbreviate potassium iodide as KI. Iodine is a trace element that naturally occurs in our environment. When iodine combines with other elements to form a salt, it’s considered an “iodide.”

Iodine exists in nature in many forms. Its stable form, iodine-127, is what you’ll find in different foods, like fish and table salt. But it also exists in many other forms (like iodine-129 and iodine-131) that are unstable and radioactive.

When should I consider discussing potassium iodide with my healthcare provider?

If you live near a nuclear power plant (especially within 10 miles or 16 kilometers), it may be a good idea to talk to your healthcare provider about preparing for an emergency. Although such emergencies are rare, having a plan in place can help ease your mind. You may wish to ask:

• Should I keep potassium iodide on hand at home?
• Is it safe for me to take potassium iodide if an emergency happens?
• What’s the appropriate dose for me?
• Is potassium iodide safe for other members of my family, including my children? What are the appropriate doses?
• What side effects should I look out for?
• What other measures should I take to stay safe during a radiation emergency?

A note from Cleveland Clinic

Our world is constantly changing. It’s normal to want to gather supplies that can protect you and your family in an emergency. Potassium iodide can protect you in some situations, but it’s important to know when and how to take it. If you live near a nuclear power plant, don’t hesitate to talk to your healthcare provider about potassium iodide. Ask about its safety for each member of your family, and make sure you understand how you should take it should an emergency arise.

If you’re taking potassium iodine for other reasons, make sure you understand the benefits and risks. Your healthcare provider can tell you more about potassium iodine’s role in your care.