In the U.S.—

In Canada—

Other commonly used names are KI; SSKI.

• Antifungal, systemic
• Antihyperthyroid agent
• Iodine replenisher
• Radiation protectant, thyroid gland
• Thyroid inhibitor

Potassium iodide (poe-TAS-ee-um EYE-oh-dide) is used to treat overactive thyroid and to protect the thyroid gland from the effects of radiation from inhaled or swallowed radioactive iodine. It may be used before and after administration of medicine containing radioactive iodine or after accidental exposure to radioactive iodine (for example, from nuclear power plant accidents that involved release of radioactivity to the environment). It may also be used for other problems as determined by your doctor.

Potassium iodide is taken by mouth. It may be taken as an oral solution, syrup, uncoated tablet, or enteric-coated delayed-release tablet. However, the delayed-release tablet form may cause serious side effects and its use is generally not recommended.

Some brands of the oral solution are available without a prescription. Use them only as directed by state or local public health authorities in case of a radiation emergency. Other forms and strengths of potassium iodide are available only with your doctor's prescription.

Potassium iodide is available in the following dosage forms:

Oral
• Delayed-release tablets (U.S.)
• Oral solution (U.S.)
• Syrup (U.S.)
• Tablets (Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For potassium iodide, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to potassium iodide, iodine, or iodine-containing foods. Also tell your health care professional if you are allergic to any substances, such as foods, preservatives, or dyes.

Pregnancy—Taking potassium during pregnancy may cause thyroid problems or goiter in the newborn infant.

Breast-feeding—Potassium iodide passes into the breast milk and may cause skin rash and thyroid problems in nursing babies.

Children—Potassium iodide may cause skin rash and thyroid problems in infants.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of potassium iodide in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than in younger adults.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking potassium iodide, it is especially important that your health care professional know if you are taking any of the following:

• Amiloride (e.g., Midamor) or
• Spironolactone (e.g., Aldactone) or
• Triamterene (e.g., Dyrenium)—Use of these medicines with potassium iodide may increase the amount of potassium in the blood and increase the chance of side effects

• Antithyroid agents (medicine for overactive thyroid) or
• Lithium (e.g., Lithane)—Use of these medicines with potassium iodide may increase the chance of side effects

• High blood levels of potassium (hyperkalemia) or
• Myotonia congenita or
• Tuberculosis—Potassium iodine may make these conditions worse

• Kidney disease—May cause an increase of potassium in the blood

• Overactive thyroid (unless you are taking this medicine for this medical problem)—Prolonged use of potassium iodine may be harmful to the thyroid gland

If potassium iodide upsets your stomach, take it after meals or with food or milk unless otherwise directed by your doctor. If stomach upset (nausea, vomiting, stomach pain, or diarrhea) continues, check with your doctor.

For patients taking this medicine for radiation exposure :

• Take this medicine only when directed to do so by state or local public health authorities.
• Take this medicine once daily until the risk of significant exposure to radiation no longer exists.Do not take more of it and do not take it more often than directed. Taking more of the medicine will not protect you better and may result in a greater chance of side effects.

For patients taking the oral solution form of this medicine:

• This medicine is to be taken by mouth even if it comes in a dropper bottle.
• Do not use if solution turns brownish yellow.
• Take potassium iodide in a full glass (8 ounces) of water or in fruit juice, milk, or broth to improve the taste and lessen stomach upset. Be sure to drink all of the liquid to get the full dose of medicine.
• If crystals form in potassium iodide solution, they may be dissolved by warming the closed container of solution in warm water and then gently shaking the container.

For patients taking the uncoated tablet form of this medicine:

• Before taking, dissolve each tablet in ½ glass (4 ounces) of water or milk. Be sure to drink all of the liquid to get the full dose of medicine.

Dosing—

The dose of potassium iodide will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of potassium iodide. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of solution or syrup or the number of tablets you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking potassium iodide.

• For solution dosage form:
  • To treat overactive thyroid (hyperthyroidism):
    • Adults and teenagers—250 milligrams (mg) (0.25 milliliters [mL]) three times a day.
    • Children—Use and dose must be determined by your doctor.
  • To protect the thyroid gland against radiation exposure:
    • Adults or teenagers approaching adult weight (greater than 70 kg or 154 lbs of body weight)—130 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children through 1 month of age—16 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children over 1 month through 3 years of age—32 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children and teenagers over 3 years through 18 years of age (less than 70 kg or 154 lbs of body weight) —65 mg once a day, until significant risk of exposure to radioiodines no longer exists.
• For syrup dosage form:
  • To protect the thyroid gland against radiation exposure:
    • Adults or teenagers approaching adult weight (70 kg or 154 lbs of body weight) greater)—130 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children through 1 month of age—16 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children over 1 month through 3 years of age—32 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children and teenagers over 3 years through 18 years of age (less than 70 kg or 154 lbs of body weight)—65 mg once a day, until significant risk of exposure to radioiodines no longer exists.
• For tablet dosage form:
  • To protect the thyroid gland against radiation exposure:
    • Adults or teenagers approaching adult weight (70 kg or 154 lbs of body weight)—130 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children through 1 month of age—16 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children over 1 month through 3 years of age—32 mg once a day, until significant risk of exposure to radioiodines no longer exists.
    • Children and teenagers over 3 years through 18 years of age (less than 70 kg or 154 lbs of body weight)—65 mg once a day, until significant risk of exposure to radioiodines no longer exists.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the tablet form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the oral liquid forms of this medicine from freezing. Do not refrigerate.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Your doctor should check your progress at regular visits to make sure that this medicine does not cause unwanted effects.

For patients on a low-potassium diet:

• This medicine contains potassium. Check with your health care professional before you take this medicine.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. When this medicine is used for a short time at low doses, side effects usually are rare.

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common
  • Hives;  joint pain;  swelling of arms, face, legs, lips, tongue, and/or throat;  swelling of lymph glands 
  
  

• With long-term use
  • Burning of mouth or throat;  confusion ;  headache (severe);  increased watering of mouth;  irregular heartbeat;  metallic taste;  numbness, tingling, pain or weakness in hands or feet;  soreness of teeth and gums;  sores on skin;  symptoms of head cold;  unusual tiredness;  weakness or heaviness of legs 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• Less common
  • Diarrhea;  nausea or vomiting;  stomach pain 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, potassium iodide is used in certain patients with the following medical conditions:

• To prepare the thyroid gland before a thyroid operation
• Iodine deficiency
• Certain skin conditions caused by fungus

In addition to the above information, for patients taking this medicine for a fungus infection:

• Keep taking it for the full course of treatment , even if you begin to feel better after a few days. This will help clear up your infection completely. Do not miss any doses .

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.