Potassium Iodide (Kaliumjodid G.L. Pharma)

What Is Potassium Iodide and What Is It Used For?

Quick Answer: Potassium iodide is a thyroid-blocking medication taken during nuclear or radiological emergencies to prevent the thyroid gland from absorbing radioactive iodine-131. It works by flooding the thyroid with stable (non-radioactive) iodine so that the gland cannot take up harmful radioactive isotopes.

Potassium iodide (chemical formula: KI) is an inorganic salt that has been recognized by the World Health Organization (WHO), the International Atomic Energy Agency (IAEA), and numerous national health authorities as an essential component of nuclear emergency preparedness. When a nuclear accident or radiological event occurs, radioactive iodine-131 (I-131) may be released into the atmosphere. This radioactive isotope can be inhaled or ingested through contaminated food and water, after which it is preferentially absorbed by the thyroid gland.

The thyroid gland, located in the front of the neck, is uniquely vulnerable to radioactive iodine because it actively concentrates iodine from the bloodstream to produce thyroid hormones (T3 and T4). When radioactive iodine accumulates in the thyroid, it delivers a concentrated radiation dose to the gland tissue, significantly increasing the risk of thyroid cancer and other thyroid disorders, particularly in children and young adults.

Kaliumjodid G.L. Pharma works through a simple but highly effective mechanism known as iodine thyroid blocking. When you take a potassium iodide tablet, the stable iodine it contains rapidly saturates the thyroid gland. Once the thyroid is fully saturated with stable iodine, it effectively cannot absorb any additional iodine — including radioactive I-131. According to WHO guidelines, when administered within the optimal time window of 2 hours before to 2 hours after exposure, potassium iodide provides approximately 97–99% blocking efficacy.

It is critically important to understand that potassium iodide protects only the thyroid gland. It does not protect against other types of radiation exposure and does not remove radioactive iodine that has already been absorbed by the thyroid. It is also not effective against other radioactive isotopes such as cesium-137 or strontium-90 that may be released during nuclear events. For comprehensive radiation protection, potassium iodide should be used as part of a broader emergency response that may include sheltering, evacuation, and avoiding contaminated food and water.

This medication is manufactured by G.L. Pharma GmbH, based in Lannach, Austria, and is also available under the brand name Kaliumjodid SERB. Each tablet contains 65 mg of potassium iodide, which is equivalent to approximately 50 mg of elemental iodine. The tablet features score lines that allow it to be divided into halves or quarters to facilitate age-appropriate dosing for children and infants.

What Should You Know Before Taking Potassium Iodide?

Quick Answer: Do not take potassium iodide if you are allergic to iodide, have dermatitis herpetiformis, hyperthyroidism, or hypocomplementemic vasculitis. Use with caution if you have thyroid disorders, kidney problems, or adrenal insufficiency. Consult a healthcare provider if you take ACE inhibitors, potassium-sparing diuretics, or antithyroid medications.

Contraindications

While potassium iodide is generally well tolerated as a single emergency dose, there are specific medical conditions in which this medication should not be used. Understanding these contraindications is important for safe use during emergency situations.

Do not take potassium iodide if you have any of the following conditions:

• Allergy to potassium iodide or any excipient: If you have a known hypersensitivity to iodide compounds or any of the inactive ingredients in the formulation, you should not take this medication. Note that iodide allergy is distinct from reactions to iodinated contrast media used in medical imaging.
• Dermatitis herpetiformis (Duhring disease): This autoimmune skin condition characterized by intensely itchy blisters is closely associated with iodide sensitivity. Taking potassium iodide can trigger severe flare-ups of this condition.
• Hyperthyroidism (overactive thyroid): If your thyroid gland already produces excessive amounts of thyroid hormones, taking additional iodide can worsen the condition or trigger a thyroid storm, a life-threatening medical emergency.
• Hypocomplementemic vasculitis: This condition, which affects the walls of small blood vessels, can be exacerbated by iodide intake.

Warnings and Precautions

Speak with a healthcare provider before taking potassium iodide if any of the following conditions apply to you. In many nuclear emergency scenarios, the benefit of thyroid protection may still outweigh the risks, but medical supervision is advised where possible.

• Thyroid cancer or suspected thyroid malignancy: The effects of iodide loading on thyroid tumors require careful medical assessment.
• Bronchial narrowing or respiratory conditions: Potassium iodide may worsen breathing difficulties in individuals with pre-existing airway constriction.
• Current or past thyroid treatment: If you are being treated or have previously been treated for thyroid conditions, your doctor should assess the appropriateness of iodide supplementation.
• Autonomous thyroid function: Untreated autonomously functioning thyroid nodules may respond unpredictably to a large iodide load.
• Kidney problems: Impaired renal function can affect the clearance of potassium from the body, potentially leading to hyperkalemia (elevated blood potassium levels).
• Adrenal insufficiency: Individuals with compromised adrenal function may have altered responses to iodide.
• Dehydration or heat cramps: These conditions can exacerbate the risk of electrolyte imbalances when taking potassium-containing medications.

Pregnancy and Breastfeeding

During a nuclear emergency, the protection of the thyroid gland is especially important for pregnant and breastfeeding women, as radioactive iodine can cross the placenta and be excreted in breast milk.

Pregnancy: Pregnant women of all ages should take 2 tablets (130 mg potassium iodide) but must not take more than a single dose. The developing fetal thyroid begins to concentrate iodine from approximately 12 weeks of gestation, making both the mother and fetus vulnerable to radioactive iodine exposure. When potassium iodide is taken during late pregnancy, it is recommended that the newborn’s thyroid function be monitored after birth, as excess iodide can temporarily suppress neonatal thyroid function.

Breastfeeding: Breastfeeding women of all ages should also take 2 tablets (130 mg potassium iodide) as a single dose only. Iodide is excreted in breast milk, but the concentrations are not sufficient to fully protect the nursing infant. Therefore, breastfed infants must also receive their own age-appropriate dose of potassium iodide for adequate thyroid protection.

Lactose Content

This medication contains lactose (milk sugar) as an excipient. If you have been told by a doctor that you have an intolerance to certain sugars, consult your doctor before taking this medicine. For most individuals, the small amount of lactose in one or two tablets is unlikely to cause significant digestive issues, even in those with mild lactose intolerance.

Effects on Driving and Machine Operation

Potassium iodide has no known effect on the ability to drive vehicles or operate machinery. There are no central nervous system effects that would impair cognitive function or reaction time at the recommended emergency doses.

How Does Potassium Iodide Interact with Other Drugs?

Quick Answer: Potassium iodide can interact with ACE inhibitors, potassium-sparing diuretics, quinidine, and antithyroid medications. It may also interfere with radioiodine therapy and thyroid function tests. Always inform your healthcare provider about all medications you are taking.

Although potassium iodide is typically taken as a single emergency dose, it is important to be aware of potential drug interactions, particularly if repeated dosing becomes necessary during a prolonged nuclear emergency. The following interactions have been documented in clinical and pharmacological literature.

Major Interactions

Additional Considerations

Radioiodine therapy: Potassium iodide can significantly interfere with radioiodine treatment used for thyroid cancer or hyperthyroidism. If you are scheduled for or currently undergoing radioiodine therapy, the administration of stable iodide will block the therapeutic effect of the radioactive iodine treatment. Inform your treating physician if you have recently taken potassium iodide tablets.

Thyroid function tests: Taking potassium iodide can alter the results of thyroid function tests, potentially leading to misleading readings. If you need thyroid testing after taking potassium iodide, inform the laboratory and your healthcare provider so that results can be interpreted appropriately. The Wolff-Chaikoff effect, where high iodide concentrations temporarily inhibit thyroid hormone synthesis, typically resolves within days to weeks after the last dose.

Lithium: Lithium, used to treat bipolar disorder, also has antithyroid effects. Combined use with potassium iodide may have additive thyroid-suppressing effects, particularly with repeated dosing. If you take lithium and require potassium iodide during a nuclear emergency, thyroid function monitoring is recommended.

Other potassium-containing supplements: Taking potassium iodide alongside other potassium supplements or potassium-rich salt substitutes may contribute to elevated blood potassium levels, particularly in individuals with impaired kidney function. A single emergency dose is unlikely to cause clinically significant hyperkalemia in otherwise healthy individuals, but caution is warranted with repeated doses.

What Is the Correct Dosage of Potassium Iodide?

Quick Answer: Adults under 40 and adolescents over 12 take 2 tablets (130 mg). Children 3–12 years take 1 tablet (65 mg). Children 1 month to 3 years take half a tablet. Neonates under 1 month take a quarter tablet. Take as early as possible after an official emergency announcement, ideally within 2 hours.

Potassium iodide tablets should only be taken during a confirmed nuclear or radiological emergency, as directed by public health authorities through official channels such as radio, television, or government emergency broadcasts. Do not take these tablets on your own initiative. Timing is critical: for optimal thyroid protection, the tablet should be taken as soon as possible after the official announcement, ideally within 2 hours. However, the medication still provides meaningful benefit when taken up to 8 hours after exposure to radioactive iodine.

Adults and Adolescents (Under 40 Years)

Adults under the age of 40 and children over 12 years should take 2 tablets (130 mg potassium iodide). The tablets may be swallowed whole or chewed. This dose provides full thyroid saturation for approximately 24 hours. A single dose is usually sufficient to protect against a single release event.

Children

Dosing for children is weight- and age-adjusted to provide appropriate thyroid protection while minimizing the risk of side effects:

For infants and young children, the tablets can be crushed or dissolved in water, juice, or a similar liquid. Complete dissolution may take up to 6 minutes. Ensure the tablet is fully dissolved before administering to the child.

Adults Over 40 Years

Adults over the age of 40 are generally not recommended to take potassium iodide. This is because the risk of radiation-induced thyroid cancer decreases significantly with age, and older adults are more susceptible to the adverse thyroid effects of iodide loading, including iodine-induced hyperthyroidism (Jod-Basedow phenomenon). The WHO and most national regulatory authorities agree that the risk-benefit ratio does not favor routine KI prophylaxis in this age group.

Exception: Adults over 40 who are at risk of very high doses of radioactive iodine exposure — such as emergency first responders, rescue workers, and decontamination personnel — should take the full adult dose of 2 tablets (130 mg). For adults over 60, no more than a single dose should be administered.

Repeated Dosing

A single dose of potassium iodide provides protection for approximately 24 hours. If the release of radioactive iodine continues beyond 24 hours, with ongoing exposure through the air, contaminated food, or contaminated drinking water, and if evacuation is not possible, repeated daily dosing may be necessary as directed by health authorities. However, the following groups should receive only a single dose and should not take repeated doses unless specifically instructed by a physician:

• Neonates (infants under 1 month of age)
• Pregnant women
• Breastfeeding women
• Adults over 60 years of age

Overdose

Symptoms of acute iodide toxicity may include a metallic taste in the mouth, excessive salivation, burning sensation in the mouth and throat, nausea, vomiting, and diarrhea. In severe cases, cardiovascular collapse, laryngeal edema, and renal failure have been reported. Treatment is supportive and may include gastric lavage if the ingestion is recent, along with correction of electrolyte imbalances.

What Are the Side Effects of Potassium Iodide?

Quick Answer: Most people tolerate a single emergency dose of potassium iodide well. Rare side effects include temporary skin rash. With prolonged use, more significant effects such as thyroid disorders, salivary gland inflammation, and gastrointestinal disturbances may occur. Hypersensitivity reactions are possible but uncommon.

Like all medicines, potassium iodide can cause side effects, although not everyone experiences them. The risk and severity of side effects depend largely on the dose and duration of use. A single emergency dose is associated with a very low incidence of adverse effects, while repeated or prolonged use carries a higher risk of thyroid and systemic complications.

The thyroid-related side effects are of particular clinical significance. The Wolff-Chaikoff effect describes the transient decrease in thyroid hormone synthesis that occurs when the thyroid is exposed to high concentrations of iodide. In most individuals, the thyroid gland “escapes” from this effect within 24–48 hours through a process called the Wolff-Chaikoff escape. However, in some vulnerable populations — particularly neonates, individuals with pre-existing thyroid disorders, and the elderly — this escape mechanism may fail, leading to prolonged hypothyroidism.

Conversely, the Jod-Basedow phenomenon describes iodine-induced hyperthyroidism, which is more common in individuals with pre-existing autonomous thyroid nodules or subclinical thyroid conditions. This is one of the primary reasons why adults over 40, who are more likely to have subclinical thyroid pathology, are not routinely recommended to take potassium iodide during nuclear emergencies.

For the vast majority of individuals receiving a single emergency dose, the benefits of thyroid protection from radioactive iodine far outweigh the small risk of adverse effects. The WHO has consistently affirmed this position in its guidance on iodine thyroid blocking during nuclear emergencies.

How Should You Store Potassium Iodide?

Quick Answer: Store at or below 25°C (77°F) in the original packaging. Keep away from light and moisture. Store out of reach of children. Do not use after the expiry date on the packaging.

Proper storage of potassium iodide tablets is essential to maintain their effectiveness, particularly since these tablets are typically stored for extended periods as part of household nuclear emergency preparedness. The following storage conditions should be observed:

• Temperature: Store at a temperature not exceeding 25°C (77°F). Avoid exposure to excessive heat, which can accelerate the degradation of the active ingredient. Do not freeze.
• Light protection: The tablets are sensitive to light. Keep them in the original blister packaging to protect against light-induced degradation.
• Moisture protection: Potassium iodide is hygroscopic, meaning it readily absorbs moisture from the air. Exposure to humidity can cause the tablets to degrade, change color, or lose potency. Always store in the original sealed packaging.
• Child safety: Keep out of sight and reach of children at all times.
• Expiry date: Do not use the tablets after the expiry date printed on the blister pack and carton (marked “EXP”). The expiry date refers to the last day of the indicated month. When tablets reach their expiry date, contact your pharmacist about proper disposal and replacement.

As part of household emergency preparedness, periodically check the expiry date of your potassium iodide tablets and replace them before they expire. Many countries distribute these tablets to households within proximity to nuclear facilities as a public health measure.

Disposal: Do not dispose of potassium iodide tablets in wastewater or household waste. Return expired or unused tablets to a pharmacy for environmentally responsible disposal.

What Does Potassium Iodide G.L. Pharma Contain?

Quick Answer: Each tablet contains 65 mg potassium iodide (equivalent to 50 mg iodine) as the active substance. Excipients include maize starch, lactose monohydrate, microcrystalline cellulose, butylated methacrylate copolymer, and magnesium stearate.

Active Substance

The active ingredient is potassium iodide (KI). Each tablet contains 65 mg of potassium iodide, which is chemically equivalent to approximately 50 mg of elemental iodine. Potassium iodide is an inorganic ionic compound consisting of potassium cations (K+) and iodide anions (I-). It is highly soluble in water, which allows it to be rapidly absorbed in the gastrointestinal tract after oral administration.

Inactive Ingredients (Excipients)

• Maize starch: Used as a binder and disintegrant to help the tablet break apart for absorption.
• Lactose monohydrate: A filler and binder derived from milk sugar. Individuals with severe lactose intolerance should be aware of this excipient, though the amount per tablet is small.
• Microcrystalline cellulose (E460): A plant-derived excipient used as a filler and binder for tablet compression.
• Butylated methacrylate copolymer (basic): A coating polymer that helps protect the tablet and may aid in taste masking.
• Magnesium stearate (E572): A lubricant used during the tablet manufacturing process to prevent sticking to equipment.

Appearance and Pack Sizes

The tablets are white to off-white in color, round, and convex. One side features a pressure-sensitive cross marking, while the other side has score lines that allow the tablet to be divided into equal halves or quarters for precise age-based dosing. The tablets are available in blister packs containing 2, 4, 6, 10, or 20 tablets. Not all pack sizes may be available in every country.