Iodine is a chemical found in foods, some salts, and dietary supplements. The body does not naturally make iodine; therefore, it relies on external sources.
The recommended dietary allowance (RDA) of iodine for adults is 150 micrograms (mcg). Quantities over 1,100 mcg have been associated with an increased risk of thyroid disorders.1
National Institutes of Health. Iodine.
This article will discuss how iodine poisoning happens and what can be done about it.
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How Does Iodine Poisoning Happen?
Iodine poisoning is rare and typically only occurs when someone takes multiple large doses (several grams) of an iodine supplement. Food rarely causes iodine poisoning.1
The recommended dietary intake is 150 mcg per day for adults 19 and over. Taking over 1,100 mcg daily for an extended period is considered the upper intake level. Anything over 1,100 mcg can increase the risk of iodine-induced diseases like hyperthyroidism (an overactive thyroid).2
Main Iodine Sources
Iodine dietary supplements are typically found as potassium iodide or sodium iodide. Some supplements use kelp seaweed, which contains iodine.1
Dietary supplements that contain iodine usually have 150 mcg. Some supplements only contain iodine. These supplements tend to have a much higher dose and are often higher than the recommended daily dose. It is important to look at the supplement label, as each brand and type can contain a different amount.1
Iodine can also be found in food sources. A few foods that contain a large amount of iodine are:1
- Cod (3 ounces): 156 mcg
- Dried seaweed flakes (2 tablespoons): 116 mcg
- Oysters (3 ounces): 93 mcg
- Plain nonfat Greek yogurt (3/4 cup): 87 mcg
Recommended Dietary Allowances for Iodine
Daily RDA of iodine for the following age groups:1
- Birth to 6 months: 110 mcg
- 7 to 12 months: 130 mcg
- 1 to 3 years: 90 mcg
- 4 to 8 years: 90 mcg
- 9 to 13 years: 120 mcg
- 14 to 18 years: 150 mcg
- 19+ years: 150 mcg
Those who are pregnant should have 220 mcg, and those who are lactating should have 290 mcg per day.1
Those with thyroid conditions must refer to their healthcare provider for their recommended iodine levels.
Symptoms of Too Much Iodine
The thyroid gland can adapt to various iodine levels. In fact, a journal article from 2019 described how people with healthy thyroid glands who typically consume normal amounts of iodine can tolerate an excess of 2 grams (g) of iodine without experiencing clinical symptoms.3
However, iodine poisoning can cause mild to very severe symptoms. Below are mild and severe reactions of too much iodine.
Mild Reactions
The mild reactions of too much iodine include:41
- Burning of the mouth or throat
- Fever
- Coughing
- Abdominal pain
- Nausea
- Vomiting
- Diarrhea
Severe Reactions
When the body is unable to get rid of excess iodine and the levels become too high it can cause serious symptoms. These symptoms include:42
- Weak pulse
- Confusion
- Delirium
- Shock
- Cyanosis (bluish skin from poor circulation or inadequate blood oxygenation)
- Coma
- Death
Increased Risks in People With Thyroid Disorders
The thyroid gland uses iodine to make thyroid hormones. People with a thyroid disorder may be more sensitive to iodine consumption. Taking iodine supplements or eating foods high in iodine can worsen hyperthyroidism.3
Consuming too much iodine can also cause thyroid disorders. Too much iodine is a risk factor for hypothyroidism (an underactive thyroid), hyperthyroidism, goiters, and thyroid autoimmune diseases.
Iodine’s Role in Thyroid Health
Ridding the Body of Iodine at Home
Iodine poisoning is a serious medical condition that needs immediate treatment by a healthcare provider. Do not induce vomiting unless instructed by the poison control or a healthcare provider.4
Do give someone with iodine poisoning milk or cornstarch or flour mixed with water. Give milk every 15 minutes. Do not give anything to a person who may have trouble swallowing. This could be because they are vomiting, seizing, confused, or have decreased alertness.4
Hospitalization for Iodine Poisoning
When someone has iodine poisoning, do not delay medical care. Once they are in the hospital, treatment will depend upon how critically ill they are.
They may receive the following treatments or support:4
- Activated charcoal
- Blood tests
- Urine tests
- Chest X-ray
- Intravenous (IV) fluids
- Breathing tube (intubation) with a breathing machine (mechanical ventilator)
- Laxative
Healthcare providers will monitor their vital signs to determine the best level of care and future needs.
Summary
Iodine is a necessary chemical used by the thyroid gland. When too much iodine is consumed, there is a potential of developing iodine poisoning. While far less common than an iodine deficiency, iodine poisoning is a medical emergency that needs immediate attention. A healthcare provider will determine the necessary care level and may use treatments like activated charcoal.