Potassium iodide is a chemical compound, medication, and dietary supplement.[4][5] It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used.[6] In the third world it is also used for treating skin sporotrichosis and phycomycosis.[6][7] It is a supplement used by people with low dietary intake of iodine.[5] It is administered orally.[6] Common side effects include vomiting, diarrhea, abdominal pain, rash, and swelling of the salivary glands.[6] Other side effects include allergic reactions, headache, goitre, and depression.[7] While use during pregnancy may harm the baby, its use is still recommended in radiation emergencies.[6] Potassium iodide has the chemical formula KI.[8] Commercially it is made by mixing potassium hydroxide with iodine.[9][10] Potassium iodide has been used medically since at least 1820.[11] It is on the World Health Organization's List of Essential Medicines.[12] Potassium iodide is available as a generic medication and over the counter.[13] Potassium iodide is also used for the iodization of salt.[5]Dietary supplement Potassium iodide is a nutritional supplement in animal feeds and also in the human diet. In humans it is the most common additive used for iodizing table salt (a public health measure to prevent iodine deficiency in populations that get little seafood). The oxidation of iodide causes slow loss of iodine content from iodised salts that are exposed to excess air. The alkali metal iodide salt, over time and exposure to excess oxygen and carbon dioxide, slowly oxidizes to metal carbonate and elemental iodine, which then evaporates.[14] Potassium iodate (KIO3) is used to iodize some salts so that the iodine is not lost by oxidation. Dextrose or sodium thiosulfate are often added to iodized table salt to stabilize potassium iodide thus reducing loss of the volatile chemical.[15] Thyroid protection See also: Nuclear accidents Pheochromocytoma seen like a dark sphere in center of the body. Image is by MIBG scintigraphy with radiation from radioiodine in the MIBG. Note unwanted uptake of radioiodine from the pharmaceutical by the thyroid gland in the neck, in both images (front and back) of the same patient. Radioactivity is also seen in the bladder. Thyroid iodine uptake blockade with potassium iodide is used in nuclear medicine scintigraphy and therapy with some radioiodinated compounds that are not targeted to the thyroid, such as iobenguane (MIBG), which is used to image or treat neural tissue tumors, or iodinated fibrinogen, which is used in fibrinogen scans to investigate clotting. These compounds contain iodine, but not in the iodide form. Since they may be ultimately metabolized or break down to radioactive iodide, it is common to administer non-radioactive potassium iodide to ensure that iodide from these radiopharmaceuticals is not sequestered by the normal affinity of the thyroid for iodide. The World Health Organization (WHO) provides guidelines for potassium iodide use following a nuclear accident. The dosage of potassium iodide is age-dependent: neonates (<1 month) require 16 mg/day; children aged 1 month to 3 years need 32 mg/day; those aged 3-12 years need 65 mg/day; and individuals over 12 years and adults require 130 mg/day.[16] These dosages list mass of potassium iodide rather than elemental iodine.[17][16] Potassium iodide can be administered as tablets or Lugol solution.[16] The same dosage is recommended by the US Food and Drug Administration.[18] A single daily dose is typically sufficient for 24-hour protection.[16] However, in cases of prolonged or repeated exposure, health authorities may recommend multiple daily doses.[16] Priority for prophylaxis is given to the most sensitive groups: pregnant and breastfeeding women, infants, and children under 18 years.[16] The recommended doses of potassium iodide, which contains a stable isotope of iodine, only protect the thyroid gland from radioactive iodine.[16] It does not offer protection against other radioactive substances.[16] Some sources recommend alternative dosing regimens.[specify][19] Not all sources are in agreement on the necessary duration of thyroid blockade, although agreement appears to have been reached about the necessity of blockade for both scintigraphic and therapeutic applications of iobenguane. Commercially available iobenguane is labeled with iodine-123, and product labeling recommends administration of potassium iodide 1 hour prior to administration of the radiopharmaceutical for all age groups, [20] while the European Association of Nuclear Medicine recommends (for iobenguane labeled with either isotope), that potassium iodide administration begin one day prior to radiopharmaceutical administration, and continue until the day following the injection, with the exception of new-borns, who do not require potassium iodide doses following radiopharmaceutical injection.[19][