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What Is Iodine? – Uses, Side Effects, and More

Iodine is an essential mineral, meaning your body needs it to function properly. You can’t produce it independently and must ingest it through your diet or as a supplement.

Iodine is important for thyroid function. The thyroid is a butterfly-shaped organ in your neck that produces hormones that regulate bodily activities, like metabolism (the conversion of food to energy).

You can find iodine in foods, but amounts can be hard to identify. Iodized salt is the primary source of this mineral in the United States. Most people should regularly use salt enriched with iodine to get enough in their diet.1

What is Iodine and How Does the Supplement Work?

This article discusses the benefits of iodine and how much iodine you need. It also covers what happens when you get too little or too much iodine.

Dietary supplements are not regulated in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement that has been tested by a trusted third party, such as USP, ConsumerLabs, or NSF.

However, even if supplements are third-party tested, that doesn’t mean that they are necessarily safe for all people or effective in general. It is important to talk to your healthcare provider about any supplements you plan to take and to check in about any potential interactions with other supplements or medications.

Supplement Facts

  • Active ingredient(s): Potassium iodide, sodium iodide
  • Alternate name(s): N/A
  • Legal status: Available over the counter (OTC) and by prescription
  • Suggested dose: 90-130 micrograms per day for children, 150 micrograms per day for adults (and teens 14-18), 220 micrograms per day during pregnancy
  • Safety considerations: Excessive iodine can impact the thyroid and lead to goiter, high TSH levels, and hypothyroidism; supplements can interact with some thyroid medications, ACE inhibitors, and diuretics

Uses of Iodine

Iodine is an essential part of the thyroid hormones thyroxine (T4) and triiodothyronine (T3) made by your thyroid gland. Both of these hormones contain iodide (a form of iodine).2 Thyroid hormones have the following functions in the body:3

  • Help cells make protein
  • Regulate activity of enzymes (proteins that create chemical reactions in the body)
  • Determine metabolism

For the most part, people take iodine to prevent or treat iodine deficiency, which can cause problems with fetal development, cognitive function, and thyroid function. In addition, some people use iodine for fibrocystic breasts and to prevent thyroid cancer when exposed to radiation. Some of these uses are better supported by research than others.

Fetal Development

Since 50% more iodine is required during pregnancy to meet fetal developmental needs, some research has examined how iodine deficiency impacts fetal development.3

For example, in a 2013 study published in Lancet, researchers evaluated the effect of insufficient iodine in pregnancy on cognitive outcomes in children.4 Researchers measured urinary iodine concentration in 1,040 pregnant participants during the first trimester. Later, they also measured the children’s intelligence quotient (IQ) at age 8.

Compared to those with adequate iodine, those with mild-to-moderate iodine deficiency were more likely to have the lowest scores for verbal IQ, reading accuracy, and reading comprehension.

In addition, a 2019 study published in Nutrients evaluated educational outcomes in adolescents whose gestational parents had mild iodine deficiency in pregnancy.5

First, researchers assessed the iodine concentration of 266 pregnant people attending antenatal clinics at the Royal Hobart Hospital in Australia from 1999 to 2000. Then, researchers compared their children’s standardized test scores in literacy and math when they were ages 8–9, 10–11, 12–13, and 14–15 years.

The study found that even mild iodine deficiency in pregnancy had long-term cognitive effects. However, these effects did not resolve with sufficient iodine intake during childhood. For example, children whose parents had iodine deficiency in pregnancy had reduced scores in reading, spelling, and grammar, independent of other factors known to impact learning.

Fibrocystic Breasts

Fibrocystic breasts are a benign condition where breast tissue is lumpy. Since breast tissue has a high concentration of iodine, some research has evaluated whether the mineral could be helpful in fibrocystic breasts.3

For example, in a 2018 study published in the Journal of Women’s Health, researchers evaluated whether a nutritional supplement including iodine could decrease cyclical breast pain and nodules.6 The randomized, multi-center, controlled, double-blind trial included 188 participants.

Researchers randomized participants to receive either a nutritional formula containing 1 gram (g) gamma-linolenic acid (GLA), 750 micrograms (mcg) iodine, and 70 mcg selenium, or a placebo daily for three menstrual cycles. While breast pain decreased in both groups, nodules decreased in the supplement group but not in the control group.

Radiation-Induced Thyroid Cancer

Nuclear accidents can release radioactive iodine (Iodine-131) into the environment, increasing the risk of thyroid cancer in those exposed. Therefore, some research has evaluated whether iodine supplementation could reduce cancer risk in high-risk populations following some historic nuclear disasters.

For example, in 1993, the American Journal of Medicine published a study examining the benefits and risks of iodide supplements in Poland following the 1986 Chernobyl nuclear power plant meltdown.7 That study found that where potassium iodide was widely used, thyroid cancer rates did not increase substantially in the following years. On the other hand, in Belarus and Ukraine, where people did not use iodine supplements, thyroid cancer increased significantly among children and adolescents.

FDA Recommendations

The FDA recommends potassium iodide as a thyroid blocking agent in nuclear emergencies.8

Other

Other uses mainly include managing thyroid conditions caused by an iodine deficiency. Those uses are explored more below.

Iodine Deficiency

If your iodine intake falls below 10–20 mcg/day, you may become deficient. Iodine deficiency leads to problems with thyroid hormone production, which can result in thyroid disease, including goiter (enlarged thyroid) and hypothyroidism (underactive thyroid).

In addition, iodine deficiency can lead to cognitive disabilities in children whose gestational parents did not have adequate intake during pregnancy.1

What Causes an Iodine Deficiency?

Since the body does not make iodine on its own, you need to obtain enough of it in your diet. If you do not get enough iodine through diet or supplements, you may become deficient.

Since the introduction of iodized salt, iodine deficiency has been rare in the U.S. However, some groups are at increased risk for a deficiency, including:3

  • People who don’t use iodized salt
  • Pregnant people
  • Vegans
  • Those with marginal iodine status who eat goitrogens (foods that interfere with the uptake of iodine in the thyroid)

Some goitrogens include broccoli, cabbage, cauliflower, kale, and strawberries. If you have normal thyroid function and iodine intake, you don’t need to worry about these foods causing an iodine deficiency.

How Do I Know If I Have an Iodine Deficiency?

Goiter is often the first clinical sign of iodine deficiency. A goiter is an enlarged thyroid that is sometimes visible or palpable through the neck. This enlargement happens because the thyroid grows so it can try to absorb as much iodine as possible.

Goiter symptoms include:9

  • Neck lump
  • Throat tightness
  • Coughing
  • Hoarseness
  • Trouble breathing or swallowing

In addition, if you have iodine deficiency, you may develop hypothyroidism. This happens because the thyroid has too little iodine to make thyroid hormone.

Hypothyroidism can cause a variety of symptoms, including:10

  • Weight gain
  • Diminished energy
  • Sleepiness
  • Dry skin
  • Trouble concentrating
  • Depression
  • Constipation
  • Feeling cold all the time

Children with hypothyroidism may experience the same effects as adults and additional symptoms, including slow physical growth, mood problems, trouble concentrating, and learning difficulties.11

Newborn screening tests can detect iodine deficiency in infants. Deficiency may cause babies to develop congenital hypothyroidism. Symptoms may include trouble eating, being excessively sleepy, or having constipation. Sometimes, it may not cause any symptoms at all.12

What Are the Side Effects of Iodine?

Your provider may recommend you take iodine during pregnancy or for deficiency. However, consuming a supplement like iodine may have potential side effects. These side effects may be common or severe.

Common Side Effects

In general, moderate iodine consumption from iodized salt or the food in your diet shouldn’t cause problems. That is because the body eliminates extra iodine through the urine.3

Allergies and sensitivities to iodine have been reported. However, more recent research suggests that iodine allergies may actually be due to another substance and not iodine. Usually, this occurs with exposure to iodine contrast material for medical testing, not from iodine supplements.

For example, a 2021 review in the American Journal of Health System Pharmacy looked at common misperceptions of iodine allergy.13 Researchers found that among 81 articles, iodine was not seen as the allergen responsible for allergic reactions to iodinated contrast media, amiodarone (a drug that regulates heart rate), povidone-iodine (antiseptic skin disinfectant used before surgery), and other iodine-containing compounds.

Mild allergic reactions to iodine contrast materials include:14

  • Headache
  • Nausea
  • Hives
  • Rash
  • Sweating

Severe Side Effects

Although rare, allergic reactions can also be severe. Anaphylaxis is a life-threatening emergency that can occur without warning due to exposure to an allergen. Symptoms include:15

  • Hives
  • Throat swelling
  • Wheezing
  • Unconsciousness
  • Hoarseness
  • Trouble swallowing
  • Vomiting
  • Diarrhea
  • Face flushing

If you experience any of the above symptoms, it is critical to seek emergency medical care immediately.

Precautions

Iodine supplements may interact with some medications, including:3

If you take any medications, talk to a healthcare provider or pharmacist about the safety of any supplements you consider taking.

Dosage: How Much Iodine Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

Since your body produces thyroid hormones on an ongoing basis, all children and adults need to consume iodine regularly. In addition, pregnant people need higher amounts to support the developing fetus.

The United States Institute of Medicine recommends the amount of iodine a person should ingest daily.3

Recommended Iodine Intake

  • 110 micrograms (mcg) per day for infants birth-6 months
  • 130 mcg per day for infants 7-12 months
  • 90 mcg per day for kids 1-8 years
  • 120 mcg per day for kids 9-13
  • 150 mcg per day for adults and teens over 14
  • 220 mcg per day during pregnancy
  • 290 mcg during lactation

You can not measure iodine levels in the blood, but you can measure it in the urine. Normal urinary iodine concentrations range between 100 and 200 micrograms per liter. Values lower than 20 micrograms per liter suggest inadequate iodine intake.3

Medical Use

Radioactive iodine is a medical treatment for conditions like thyroid cancer or goiter. It works by destroying overactive thyroid tissue or thyroid cancer cells.16

This treatment comes as a prescription pill and requires a special low iodine diet one to two weeks before starting treatment.

Radioactive iodine can be harmful to others, so healthcare providers recommend precautions to protect other people. Precautions include maintaining distance from other people while your body gives off radiation.

What Happens If I Take Too Much Iodine?

You can consume more iodine than your body can handle by using supplements that contain high doses of iodine. Chronic iodine overdose is associated with goiter, hyperthyroidism (overactive thyroid), thyroiditis (thyroid inflammation), and thyroid cancer.3

Toxicity is rare but can occur from consuming heavy doses (usually many grams) of iodine supplements. Signs of iodine poisoning include:

  • Mouth, throat, or stomach burning
  • Fever
  • Abdominal pain
  • Nausea
  • Vomiting
  • Diarrhea
  • Weak pulse
  • Coma

To avoid toxicity, be aware of the appropriate dosage (above) and stay below the safe upper limit established by the Institute of Medicine.3

Upper Limits

200 mcg for children 1-3 years

300 mcg for children 4-8 years

600 mcg for kids 9-13 years

900 mcg for teens 14-18 years

1,100 mcg for all adults, including those who are pregnant and lactating

If you consume more than these amounts or more than what is recommended by your healthcare provider, you may want to go to the emergency room.

How to Store Iodine

Store iodine in a cool, dry place. Keep it away from direct sunlight. Discard after one year or as indicated on the packaging.

FREQUENTLY ASKED QUESTIONS

  • What is an iodine solution?

    An iodine solution is a topical iodine preparation that sterilizes the skin to prevent infection. Potassium iodide (KI), used in radioactive emergencies, is also available as a solution.17

  • Can iodine deficiency cause low energy levels?

    Iodine deficiency can affect your thyroid hormone levels, causing low energy. However, iodine deficiency does not independently affect energy levels. Instead, the lack of iodine reduces the thyroid’s ability to produce thyroid hormone, which can cause a range of symptoms, including low energy.

  • Can eating salty foods cause iodine toxicity?

    Eating salty foods should not cause iodine toxicity. The body will automatically eliminate excess iodine when you urinate. However, consuming excess iodine supplements is not safe and can lead to toxicity. Signs of iodine poisoning include an upset stomach, mouth and throat burning, diarrhea, and vomiting.

Sources of Iodine and What To Look For

Iodine is found in food sources and is also available as a supplement. Most people can meet their iodine needs through food sources.

Food Sources of Iodine

The most common source of iodine is iodized salt, which contains 76 mcg (51% of the daily recommended intake for adults) in a quarter teaspoon. However, this concentration may differ depending on the manufacturer. For precise amounts, check the label’s nutritional information.

In addition, plenty of foods contain iodine. Fish and seaweed are the foods richest in iodine. For example, one 3-ounce serving of cod contains about 158 mcg of iodine, and one serving of seaweed contains about 116 mcg of iodine. Other iodine-rich foods include:3

  • Bread made with iodate dough
  • Oysters
  • Yogurt
  • Milk
  • Enriched pasta boiled in iodized salt
  • Eggs

Supplements

Vitamins and supplements vary in their iodine content. You can find the specific amount of iodine on the label. Talk with your healthcare provider before taking a supplement.

Iodine supplements most often come as potassium iodide or sodium iodide. Some iodine supplements are also sourced from kelp (seaweed).3 They are available in drops, capsules, and tablets. If you are vegan or have food allergies, read labels carefully to ensure there are no animal products or allergens.

Iodine is quickly absorbed in the stomach and small intestine. Next, it travels through the bloodstream. From there, iodine receptors located in the thyroid bind to it and take it in.

Do not use iodine supplements unless you are diagnosed with iodine deficiency. If you need iodine supplements, your healthcare provider will give you a prescription. You might be able to use an OTC supplement. If so, verify that the dose is exactly as prescribed by your healthcare provider.

Summary

Iodine is a mineral your body needs for producing thyroid hormones. These hormones have essential roles in regulating body weight and maintaining energy.

Iodine deficiency can lead to hypothyroidism, where the thyroid doesn’t produce enough hormones. It can also cause an enlarged thyroid, called a goiter.

Common sources of iodine include salt, supplements, and foods like vegetables and seafood. Consult a healthcare provider before taking any supplements.

A Word From Verywell

Iodine deficiency is rare in countries where iodized salt is regularly used. However, if you have a thyroid problem, a healthcare provider may instruct you to maintain a low iodine diet or supplement your diet with iodine.

If you’ve had an iodine deficiency in the past, check with your doctor about regular monitoring of your thyroid hormone levels. Regular check-ups are the best way to know whether you are getting enough iodine.


10 Uses for Iodine: Do Benefits Outweigh the risks?

What is iodine?

Also called iodide, iodine is a type of mineral that’s naturally found in the earth’s soil and ocean waters. Many salt water and plant-based foods contain iodine, and this mineral is most-widely available in iodized salt.

It’s important to get enough iodine in the diet. It regulates hormones, fetal development, and more.

If your iodine levels are low, your doctor might recommend supplementation. You shouldn’t take supplements without checking with your doctor first.

Read on to learn more about the uses and side effects of iodine, plus recommended daily amounts by age.

10 uses of iodine

Iodine is considered an essential mineral for our bodies. It’s particularly important during pregnancy, and exposure in the womb may even help prevent certain health conditions later in life.

The following is a list of some of the most important uses and how they benefit the body.

1. Promoting thyroid health

Iodine plays a vital role in thyroid health. Your thyroid gland, which is located at the base of the front of your neck, helps regulate hormone production. These hormones control your metabolism, heart health, and more.

To make thyroid hormones, your thyroid takes up iodine in small amounts. Without iodine, thyroid hormone production can decrease. A “low” or underactive thyroid gland can lead to a condition called hypothyroidism.

Given the wide availability of iodine in western diets, thyroid health isn’t typically impacted by low iodine levels in the United States.

You can get enough iodine from your diet by eating dairy products, fortified foods, and salt water fish. Iodine is also available in plant foods that grow in naturally iodine-rich soil. You also can get the mineral by seasoning your food with iodized salt.

While iodine promotes overall thyroid health, too much iodine can have a negative effect on the thyroid gland. That’s why you shouldn’t take iodine supplements without your doctor’s recommendation.

2. Reducing risk for some goiters

goiter is an enlarged thyroid gland. Your thyroid may become enlarged as a result from either hypothyroidism or hyperthyroidism. Hyperthyroidism is an overactive thyroid gland.

Non-cancerous thyroid nodules (cysts) can also cause thyroid gland enlargement.

Sometimes a goiter develops as a direct response to iodine deficiency. This is the most common cause of goiter worldwide, though it’s not as common a cause in the United States and other countries with access to iodine-rich foods.

Iodine-induced goiters may be reversed by adding iodine-rich foods or supplements in the diet.

3. Managing overactive thyroid gland

Your doctor may recommend a special type of iodine called radioactive iodine to treat an overactive thyroid gland. Also called radioiodine, this medication is taken by mouth. It’s used to destroy extra thyroid cells to help reduce excessive amounts of thyroid hormone.

The risk with radioactive iodine is that it can destroy too many thyroid cells. This can decrease the amount of hormone production, leading to hypothyroidism. For this reason, radioactive iodine is usually only recommended after anti-thyroid drugs have failed.

Radioactive iodine is not the same thing as iodine supplements. You should never take iodine supplements for hyperthyroidism.

4. Treating thyroid cancer

Radioiodine may also be a possible treatment option for thyroid cancer. It works in much the same way as hyperthyroid treatment.

When you take radioactive iodine orally, the medication destroys thyroid cells, including cancerous ones. It may be used as a treatment following thyroid surgery to make sure all cancerous cells have been removed from the body.

According to the American Cancer SocietyTrusted Source, radioactive iodine treatments significantly improve the chances of survival for people with thyroid cancer.

5. Neurodevelopment during pregnancy

You need more iodine in pregnancy. That’s because iodine intake during pregnancy is linked to brain development in fetuses. One reviewTrusted Source found that babies whose birth mothers had an iodine deficiency during pregnancy were more likely to grow up with lower IQ’s and other intellectual delays.

The recommended daily intakeTrusted Source of iodine during pregnancy is 220 mcg. By comparison, the recommended amount in non-pregnant adults is 150 mcg a day.

If you’re pregnant, ask your doctor about iodine supplementation, especially if your prenatal vitamin doesn’t have iodine (many do not). Iodine supplements may also be necessary if you’re deficient in the mineral.

You’ll also need to continue monitoring your iodine intake if you’re breastfeeding. The recommended daily amount of iodine while nursing is 290 mcg. That’s because the iodine you take up from diet and supplementation is transferred via breast milk to your nursing infant. This is a crucial brain developmental period, so infants need 110 mcg per day until they’ve reached 6 months of ageTrusted Source.

6. Improving cognitive function

The same neurological benefits of iodine during pregnancy may extend to healthy brain function during childhood. This also includes a reduced riskTrusted Source of intellectual disability.

It is likely your child gets all the iodine they need through their diet, but if you have any questions about their iodine intake, talk to their pediatrician.

7. May help treat fibrocystic breast disease

It’s possible that iodine supplements or medications can help treat fibrocystic breast disease. This non-cancerous condition is most common in women of reproductive age, and it can cause painful breast lumps.

Although there is some promise that iodine might help with fibrocystic breast cysts, you shouldn’t attempt self-treatment. Only take iodine for this condition if your doctor specifically recommends it. Otherwise, you could be at risk of side effects from iodine toxicity.

8. Disinfecting water

Iodine is just one method of water disinfection. This may be especially helpful if you don’t have access to potable water due to traveling or effects from a natural disaster.

Two percent liquid iodine tincture may be added to water in five-drop increments per one quart of clear water. If the water is cloudy, add ten drops per quart.

Iodine tablets may also be used, but the instructions can vary by manufacturer.

Despite the role iodine can play in disinfecting drinking water, there’s also some concerns that it can increase total iodine intake in humans and lead to adverse health effects. Total iodine intake shouldn’t exceed 2 mg per dayTrusted Source.

9. Protection from nuclear fallout

In the case of nuclear emergencies, the Centers for Disease Control and Prevention recommends the use of potassium iodide (KI) to protect the thyroid gland from radiation injuries. These are available in tablet and liquid formulas.

While not completely foolproof, the sooner KI is taken, the better the thyroid is thought to be protected in the event of this kind of emergency.

There are serious risks associated with KI, including gastrointestinal upset, inflammation, and allergic reaction. You’re also at increased risk for thyroid disease. Your risk for complications is higher if you already have thyroid disease.

10. Treating infections

Iodine can be used topically in a liquid form to help treat and prevent infections. It works by killing bacteria in and around mild cuts and scrapes.

Topical iodine should not be used on newborn babies. It should also not be used for deep cuts, animal bites, or burns.

Follow directions on the packaging for dosage information, and do not use for more than 10 days unless directed by your doctor.

 

Symptoms of iodine deficiency

Iodine deficiency can only be diagnosed via urine tests.

The symptoms of low iodine levels are primarily detected through thyroid symptoms, such as:

  • a visible goiter
  • thyroid gland that’s painful or tender to the touch
  • breathing difficulties, especially when lying down
  • difficulty swallowing
  • fatigue
  • extreme feelings of coldness, despite normal temperatures
  • hair loss
  • depression
  • brain fog
  • unintentional weight gain
Who should take iodine?

Your doctor might recommend iodine supplements if your levels are low. The only way to know for certain is by checking your levels through a urine test. After that point, your doctor may recommend a supplement.

Iodine is available in stronger formulas through a prescription. However, these are used for serious health conditions only. For example, your doctor may recommend prescription-strength iodine if you’ve been exposed to radiation or have an overactive thyroid gland.

If you suspect you need iodine support, check with your doctor to see if you’re a candidate.

Takeaway

Iodine is an essential nutrient. People with access to iodized salt, seafood, and certain vegetables are able to get enough iodine from their diet.

In some cases, you may need iodine supplementation to help reduce your risk for iodine deficiency, or as a treatment for certain medical conditions, such as underactive thyroid or goiter.

Talk to your doctor about your specific iodine needs.


Overview

Iodine is an element that is used by the thyroid. Humans cannot produce iodine, so it must be consumed. It is added to some foods and also to salt.

Iodine reduces thyroid hormone and can kill fungus, bacteria, and other microorganisms such as amoebas. Iodine deficiency is one of the most common and preventable world health problems. Most iodine is found in the ocean, where it is concentrated by sea life, particularly in seaweed.
Iodine is taken by mouth to prevent and treat iodine deficiency and its consequences, including goiter and some thyroid disorders. A specific kind of iodine called potassium iodide is also US FDA approved to prevent thyroid damage after a radioactive accident. Iodine is also used for pink eye, gum infections, wound healing, and many other conditions, but there is limited scientific evidence to support many of these uses.

CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.
This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
© Therapeutic Research Faculty 2020.

 

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