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Overview: Iodine/potassium iodide is a liquid you swallow to help with certain thyroid problems. The most common side effects seem to be a bitter or metallic taste, rash, or an upset stomach. Taking it with milk or juice may help hide the bad taste. Serious side effects are rare. Before taking iodine/potassium iodide, make sure to tell your health care provider about any health conditions or medicines you are taking.

Uses

What is iodine/potassium iodide (Lugol’s Solution) used for?

Iodine/potassium iodide is commonly used by certain people for the following thyroid problems. 

Iodine/potassium iodide may also be used for other conditions as determined by your health care provider.

Note: The FDA has not reviewed this medicine for safety and effectiveness, and the label is not approved by the FDA. Learn more about unapproved drugs here.

How does iodine/potassium iodide work (mechanism of action)?

Your body uses iodine to make thyroid hormones. An enlarged thyroid gland is known as a goiter. This can happen for several reasons. A simple goiter happens as a way to help your body when it is not making enough thyroid hormone. It grows bigger so it can make more hormones. A colloid goiter is very rare, but it can happen if you are not getting enough iodine from your diet. Iodine/potassium iodide gives your body iodine so it can make thyroid hormones.

Graves’ disease is a condition where your body tells your thyroid gland to make more thyroid hormone when it does not need more. This causes high thyroid hormone levels. Iodine/potassium iodide seems to temporarily reduce the amount of thyroid hormone your body makes. It may also reduce blood flow to the thyroid gland.

How is iodine/potassium iodide supplied (dosage forms)?

Brands and other names

  • Lugol’s Solution
  • Strong Iodine

Dosage forms and strengths

  • 5% iodine and 10% potassium iodide oral solution

How should I store iodine/potassium iodide?

Iodine/potassium iodide should be stored at room temperature. Most medicines should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of iodine/potassium iodide?

The most common side effects of iodine/potassium iodide are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Bitter or metallic taste
  • Rash
  • Stomach pain, nausea, vomiting, or diarrhea

There may be other side effects of iodine/potassium iodide that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of iodine/potassium iodide?

While less common, the most serious side effects of iodine/potassium iodide are described below, along with what to do if they happen.

Severe Allergic Reactions. Iodine/potassium iodide may cause allergic reactions, which can be serious. Stop taking iodine/potassium iodide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Iodine Poisoning. Taking iodine/potassium iodide for a long time may lead to iodine poisoning. This is sometimes called iodism. Follow your health care provider’s instructions on how much to take and how long to take it. Keep all appointments, including those for lab work, while you are taking it. Your health care provider will likely use labs to make sure it is working and safe for you to take. Tell your health care provider if you have any of the following symptoms of iodism.

  • Sore gums and teeth
  • Bad headaches
  • The whites of your eyes seem red
  • Your eyes water, your nose runs, or you have more spit in your mouth than usual
  • Blurry vision 

Warnings & Precautions

Who should not use iodine/potassium iodide?

Allergies to Ingredients. People who are allergic to any of the following should not take iodine/potassium iodide.

  • Iodine
  • Lugol’s solution
  • Potassium iodide
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific iodine/potassium iodide products they stock.

Tuberculosis. You should not take iodine/potassium iodide if you have tuberculosis. It may interfere with the tuberculosis healing process.

What should I know about iodine/potassium iodide before using it?

Do not take iodine/potassium iodide unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share iodine/potassium iodide with other people, even if they have the same condition as you. It may harm them.

Keep iodine/potassium iodide out of the reach of children.

Use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. If your medicine did not come with a measuring device, ask your pharmacist what measuring device to use.

Iodine/potassium iodide may have a bitter or metallic taste to it. If you take it with milk or something sweet, like apple juice, it may make it taste better. This may also help with some of the stomach-related side effects it can cause. Talk to your pharmacist about other ways to help disguise the bad taste.

What should I tell my health care provider before using iodine/potassium iodide?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if iodine/potassium iodide is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Kidney problems
  • Liver problems, including cirrhosis
  • Immune system problems, including AIDS, cancer, a previous transplant, or autoimmune conditions
  • Diabetes that is not well controlled

Other Medicines and Supplements. Iodine/potassium iodide may interact with other medicines and supplements. Before taking iodine/potassium iodide, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Iodine/potassium iodide may cause harm to a fetus. Tell your health care provider if you are pregnant or plan to become pregnant. If you become pregnant while taking iodine/potassium iodide, tell your health care provider right away.

Breastfeeding. Iodine/potassium iodide passes into breast milk. Taking it while you are breastfeeding may lead to low thyroid hormone levels in your baby. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take iodine/potassium iodide while breastfeeding.

Interactions

Does iodine/potassium iodide interact with foods or drinks?

There are no known interactions between iodine/potassium iodide and foods or drinks.

It is unknown if drinking alcohol will affect iodine/potassium iodide.

Does iodine/potassium iodide interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking iodine/potassium iodide.

  • Amiloride (Midamor), eplerenone (Inspra), spironolactone (Aldactone, Carospir), or triamterene (Dyrenium), which are types of diuretics, also called water pills
  • Potassium chloride (Klor-Con and others), which is a medicine used to raise potassium levels
  • An angiotensin-converting enzyme (ACE) inhibitor, such as enalapril or lisinopril, which is a medicine for high blood pressure, heart failure, and certain kidney problems
  • A corticosteroid, such as dexamethasone, methylprednisolone, or prednisone, which is a medicine for certain inflammatory conditions

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much iodine/potassium iodide?

If you or someone else has used too much iodine/potassium iodide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of iodine/potassium iodide?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.