What to Know About Potassium Iodide (SSKI) for Radiation Poisoning

Iodine is a trace element that’s important for controlling your body’s metabolism. Your thyroid gland uses it to make thyroid hormones.

Not all forms of iodine are created equally, though. Radioactive iodine can be released into the environment when nuclear accidents happen. It may then be inhaled or ingested from contaminated food and water sources, causing it to build up in the thyroid gland. This raises the risk of thyroid cancer.

A medication called potassium iodide (SSKI) can help prevent radiation poisoning and protect your thyroid gland during a nuclear accident. Below, we review how potassium iodide can help you in the case of a nuclear emergency.

What is potassium iodide?

Potassium iodide is a medication that blocks dangerous, radioactive iodine from building up in the thyroid gland. The thyroid gland makes hormones that have many functions, including controlling metabolism, heart rate, and body temperature.

SSKI stands for “saturated solution of potassium iodide.” It’s a brand-name, liquid version of potassium iodide that’s available with a prescription from a healthcare provider. ThyroSafe and iOSAT are brand-name tablet versions of potassium iodide that are available over the counter (OTC).

Who should take potassium iodide for radiation poisoning?

Potassium iodide helps lower the risk of thyroid cancer caused by radiation exposure during a nuclear emergency. Its use is CDC-backed for people who are pregnant, breastfeeding, or younger than 40 years old. These groups of people are more likely to develop thyroid cancer from radiation exposure.

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Potassium iodide’s risks may outweigh its benefits for people who are age 41 or older. This is because thyroid problems and other related health conditions are more common with age. However, if the expected radiation exposure is high enough, you may also be asked to take the medication by public health officials even if you’re 41 or older.

How does potassium iodide work for radiation poisoning?

As mentioned, a radioactive form of iodine can be released into the air during nuclear emergencies. This radioactive iodine can contaminate food and water. People may then inhale or consume it inadvertently, raising their risk of developing thyroid cancer.

Potassium iodide decreases the amount of radioactive iodine that builds up in the thyroid. It works by flooding the thyroid with stable, nonradioactive iodine, thereby reducing absorption of the radioactive form.

Good to know: You should only take FDA-approved or CDC-backed potassium iodide products for radiation poisoning. Dietary supplements containing iodine don’t offer sufficient protection.

How much potassium iodide should you take for radiation poisoning?

As mentioned, potassium iodide is available as oral tablets and a liquid solution.

The oral tablets are available OTC and are usually swallowed whole. But they can also be crushed and dissolved in liquid. You can mix the crushed tablets with orange juice, milk, and other liquids.

Along the same lines, you can dilute liquid SSKI solution in a glass of water, juice, or milk. This helps it taste better.

Dosages for adults

If a nuclear accident happens near you, public health officials will tell you if and when you should start taking potassium iodide. The usual adult dosage is 130 mg taken once daily. You should continue taking it daily until directed to stop by public officials. One dose provides about 24 hours of protection.

Dosages for children

Children usually take a lower dosage of potassium iodide than adults. The exact dosage depends on the child’s age and body weight. It’s important to note that the FDA recommends giving children the lowest recommended potassium iodide dosage possible. 

It may be easier to measure out the right dose for your child using the oral liquid rather than the tablet. Children and adolescents are advised to take the following daily doses:

• Infants up to 1 month old: 16 mg

• Infants 1 month old to children 3 years old: 32 mg

• Children 3-11 years old: 65 mg

• Adolescents 12-17 years old weighing less than 150 lbs: 65 mg

• Adolescents 12-17 years old weighing 150 lbs or more: 130 mg

Taking too much potassium iodide can be harmful, especially for unborn fetuses and newborns. Too much potassium iodide can prevent necessary thyroid function in a developing baby.

Newborn babies younger than 1 month old should only receive one dose of potassium iodide. Children older than 1 month of age should take their doses once daily until told otherwise by public officials.

Who shouldn’t take potassium iodide?

You shouldn’t take potassium iodide if you know that your body is sensitive to iodine. Taking it can cause an allergic or immune-related reaction.

People with extremely rare health conditions that are associated with iodine hypersensitivity also shouldn’t take potassium iodide. These may include:

• Dermatitis herpetiformis, a skin condition affecting people with celiac disease

• Hypocomplementemic urticarial vasculitis, an inflammatory condition of small blood vessels

• Nodular thyroid disease with heart disease

If you’re unsure if you should take potassium iodide, contact your healthcare provider.

What are the potential side effects of potassium iodide?

Taking potassium iodide for the recommended period of time doesn’t usually cause any major side effects. However, taking it for longer than recommended could cause serious side effects.

Common side effects

Common potassium iodide side effects include:

• Nausea

• Vomiting

• Diarrhea

• Stomach upset or pain

• Skin rash

• Swelling or pain of saliva glands

Taking the medication with food or milk can help limit stomach-related side effects.

Serious side effects

It’s possible to be allergic to potassium iodide. Call 911 or seek emergency medical help if you notice any of the following signs or symptoms of an allergic reaction:

• Trouble breathing

• Shortness of breath

• Swelling in lips, tongue, or throat

Taking high dosages of potassium iodide, or taking it for a long time, can lead to iodine poisoning. Some possible signs and symptoms of iodine poisoning include:

• Fever

• Burning sensation in the mouth

• Metallic taste in the mouth

• Sore gums and teeth

• More saliva than usual

• Feeling thirstier than usual

• Seizures

Seek immediate medical attention if you’re experiencing signs or symptoms of iodine poisoning. Contact Poison Control online or at 1-800-222-1222 if you think you’ve taken too much potassium iodide.

How effective is potassium iodide for preventing radiation poisoning?

While potassium iodide is effective, it’s not a foolproof solution for preventing radiation poisoning. Its effectiveness depends on three main things:

1. Time after exposure: You’ll have the best protection from radioactive iodine the sooner you take potassium iodide.

2. Absorption of potassium iodide: The amount of thyroid protection depends on how quickly your body absorbs potassium iodide. Faster absorption helps to prevent your thyroid from accumulating radioactive iodine.

3. Amount of radioactive iodine exposure: Your thyroid will absorb less radioactive iodine with less radiation exposure.

Our current understanding of potassium iodide’s effectiveness comes from studies of past nuclear emergencies. For instance, one well-known nuclear accident occurred at the Chernobyl nuclear power plant in Ukraine in 1986, leading to the release of radioactive iodine. Nearby children in Poland received potassium iodide to prevent radiation poisoning. It was estimated to lower the accumulation of radioactive iodine in the body by about 40% to 60%.

Keep in mind: Potassium iodide isn’t an antidote for radiation exposure. It protects the thyroid gland from radioactive iodine exposure and is taken in a preventive manner. It also doesn’t protect against other radioactive chemicals that can be released into the environment during a nuclear accident. And it doesn’t protect areas of the body outside of the thyroid gland.

How to save on potassium iodide

GoodRx can help you save over 40% off the average retail price of the generic version of potassium iodide. Generic potassium iodide’s price at certain pharmacies may be as low as $18.17 with a free GoodRx coupon. What’s more, you may be able to find brand-name iOSAT at certain pharmacies for as low as $104.73.

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Written by:

Mandeep Sohal, PharmD

Mandeep Sohal, PharmD, has more than 7 years of experience in the pharmaceutical industry and is licensed in California. In his career, he’s had experience with specialty pharmacy, community pharmacy, pharmacy benefit management, and pharmaceutical manufacturers.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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