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Potassium Iodide

pronounced as (poe tas' ee um eye' oh dide)

Why is this medication prescribed?

Potassium iodide is used to protect the thyroid gland from taking in radioactive iodine that may be released during a nuclear radiation emergency. Radioactive iodine can damage the thyroid gland. You should only take potassium iodide if there is a nuclear radiation emergency and public officials tell you that you should take it. Potassium iodide is in a class of medications called anti-thyroid medications. It works by blocking radioactive iodine from entering the thyroid gland.

Potassium iodide can protect you from the effects of radioactive iodine that may be released during a nuclear radiation emergency, but will not protect you from other dangerous substances that may be released during the emergency. Public officials may tell you to do other things to protect yourself during the emergency. Follow all of these directions carefully.

How should this medicine be used?

Potassium iodide comes as a liquid and a tablet to take by mouth. It is usually taken once a day for as many days as public officials say it is needed. Take potassium iodide at around the same time every day. If you are told to take potassium iodide during a nuclear radiation emergency, you should not take it more often than once every 24 hours. Follow the directions on the package label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take potassium iodide exactly as directed. Do not take more or less of it than directed on the package label. Taking potassium iodide more often will not give you more protection during the emergency, and will increase the risk that you may experience side effects.

The dose of potassium iodide you should take or give to your child depends on your age or your child's age. If potassium iodide is taken by a teenager between the ages of 12 to 18 years, the dose also depend on the teenager's weight. Check the package label to see what dose you should take yourself or give to your child. Ask your doctor, pharmacist, or public official if you have questions.

Potassium iodide tablets can be crushed and mixed with water and certain other liquids including low-fat white or chocolate milk, flat soda, orange juice, raspberry syrup, or infant formula so that they can be given to children or people who cannot swallow tablets. Check the package label to find out how to make this mixture and how much of this mixture you should take or give to your child. If you do make a mixture, store it in the refrigerator and use it within 7 days. Dispose of any unused mixture after 7 days.

Read the manufacturer's information for the patient carefully. Ask your doctor or pharmacist if you have any questions.

Other uses for this medicine

Potassium iodide is also sometimes used to treat overactive thyroid gland and sporotrichosis (a skin infection caused by a fungus). Talk to your doctor about the risks of using this medication for your condition.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking potassium iodide,

  • tell your doctor and pharmacist if you are allergic to potassium iodide, iodine, any other medications, or any of the ingredients in potassium iodide tablets or liquid. Ask your pharmacist or check the package label for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. If you are unable to reach your doctor, you may take potassium iodide along with your other medications.
  • tell your doctor if you have dermatitis herpetiformis (an ongoing skin disease that causes groups of itchy blisters to form on the body), hypocomplementemic vasculitis (an ongoing condition that causes frequent outbreaks of hives and other symptoms such as swelling and joint pain), or if you have both multinodular thyroid disease (many lumps in the thyroid gland) and heart disease. You should not take potassium iodide if you have any of these conditions.
  • if you have or have ever had a thyroid condition such as Graves disease (condition where the body attacks the thyroid gland causing it to be overactive) or Hashimoto's thyroiditis (swelling of the thyroid gland that causes its function to decrease), you may take potassium iodide if you are told to so in an emergency. However, you should call your doctor if you need to take potassium iodide for more than a few days.
  • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you are pregnant or breast-feeding, you may take potassium iodide if you are told to do so in an emergency, but you should call your doctor as soon as possible. Your doctor will probably monitor you carefully, and will want you to avoid taking more than one dose of potassium iodide if possible.
  • if you give potassium iodide to a baby younger than one month of age, call the baby's doctor as soon as possible. The baby's doctor will monitor the baby carefully and will want you to avoid giving the baby more than one dose of potassium iodide if possible.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one and do not take 2 doses less than 24 hours apart.

What side effects can this medication cause?

Potassium iodide may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • swollen glands
  • metallic taste in the mouth
  • nausea
  • vomiting
  • diarrhea
  • stomach ache
  • headache

Some side effects can be serious. If you experience any of these symptoms, stop taking potassium iodide and call your doctor immediately:

  • rash
  • hives
  • fever
  • joint pain
  • swelling of the face, lips, tongue, throat, hands, or feet
  • trouble breathing, speaking, or swallowing
  • wheezing
  • shortness of breath
  • irregular heartbeat
  • chest pain
  • lump under the skin at the base of the neck

Potassium iodide may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat and moisture (not in the bathroom). Some bottles of potassium iodide may be safe to use after the expiration date stamped on the bottle; ask your doctor or pharmacist for more information.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests to check your body's response to potassium iodide.

Ask your pharmacist any questions you have about potassium iodide.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Iosat®
  • Thyrosafe®
  • Thyroshield®

Other names

  • KI
Last Revised - 11/15/2016