Chemical Properties

Colorless or white cubic crystals or granules; becomes yellowish when exposed to bright light due to photochemical decomposition liberating traces of free iodine; density 3.13 g/cm3; melts at 681°C; vaporizes at 1,330°C; highly soluble in water, ~140 g/100mL at 20°C; aqueous solution readily dissolves iodine; sparingly soluble in ethanol (about 2 g/100mL at 25°C) and acetone; slightly soluble in ether and ammonia.

Potassium iodide is a chemical compound, medication, and dietary supplement. As a medication it is used to treat hyperthyroidism, in radiation emergencies, and to protect the thyroid gland when certain types of radiopharmaceuticals are used.

Medical Uses

Nuclear radiation

Shortly before or after exposure to nuclear radiation, daily intake of 130 mg of potassium iodide (adults) can effectively prevent the absorption of radioactive iodine by the thyroid, thereby reducing the accumulation of radioactive iodine, and reducing impair of radioactive iodine to the thyroid gland and nearby tissues.

Dermatological Diseases

Sporotrichosis: Potassium iodide, used either alone or in combination, has a significant effect in the treatment of spore mycosis.

Hypertrophic scars: Potassium iodide solution can inhibit the hyperplasis of scar tissue, dissipate the granulation tissue, soften the scar, loosen the adhesion, and eliminate chronic inflammation.

Erythema nodosum: Potassium iodide deposits in granuloma that cause mast cells to release heparin, thereby inhibiting the occurrence of delayed allergy.

Ophthalmic Diseases

Cataract: Potassium iodide is one of the first drugs used to treat cataract. It is effective on lens regeneration and reducing lens epithelium damage in experimental naphthalene cataract.

Blepharitis: Application of 2% potassium iodide in eye skin is effective for styes patients with myosinosis, with a cure rate of 88.4%.

Vitreous opacity: Oral administration of 10% potassium iodide can effectively promote the bleeding in the vitreous body and absorption of exudate thus reducing the opacity of vitreous body.

Chronic bronchitis:10% potassium iodide solution has good efficaty in treating chronic bronchitis.

Lead nephropathy: Potassium iodide protects the renal cells from lead damage by either blocking lead diffusion or binding with lead in the cells as to protect the Na + -k + -atpase.

Hyperplasia of mammary glands: The small dose of potassium iodide can promote the secretion of luteinizing hormone in the anterior pituitary gland and promote the luteinization of the ovarian follicle, thus reducing the estrogen level and restoring the normal function of the ovary.

Others

In the treatment of temporomandibular joint disorders, periarthritis of shoulder, congenital muscular torticollis, cervical spondylosis vertigo, clinical studies have shown that applying potassium iodide can increase sympathetic nerve excitability, promote inflammation absorption, release the conglutination and soften the scar thus helping restore the functions of the nerve.    

Side Effects

• Allergy, not common. It can occur immediately after taking the drug, or an angioedema may occur several hours later. It may happen in the upper limbs, lower extremities, face, lips, tongue, or throat. It may also have erythema, fever, or discomfort.

• Long-term use may cause oral, throat burning sensation, runny nose, metallic taste, tooth and gum pain, stomach discomfort, severe headache and other symptoms of iodine poisoning; hyperkalemia symptoms such as confusion, arrhythmia, numb and tingling feeling in hands and feet, and weakness of lower limbs may also occur. Stop taking medicine to subside.

• Gastrointestinal adverse reactions such as diarrhea, nausea, vomiting, and stomach pain may occur, though uncommon. 

• Effects on thyroid function: Excessive iodine can cause hyperthyroidism or hypothyroidism. Recession or inhibition of thyroid function can lead to excessive secretion of TSH and even goiter.

• Combination with anti-thyroid drugs may cause hypothyroidism and goiter; combination with angiotensin converting enzyme inhibitors or with potassium-sparing diuretics is prone to hyperkalemia, so potassium should be monitored in these cases; combination with lithium salts may cause hypothyroidism and goiter.