Reports from as early as 1903 mention the use of potassium iodide (KI) as an antifungal agent. The therapeutic effect is probably mediated through the direct action of iodine on yeast forms of S. schenckii; a solution of 0.02 mg/ml kills in 10 minutes. KI is used as a nutritional supplement in animal feeds and table salt. Drops of SSKI or 130 mg tablets of are used following nuclear fission accidents to minimize uptake of radioactive iodine by the thyroid gland and subsequent thyroid cancer.
Dose & Delivery
It is only effective for the treatment of sporotrichosis, basidiobolomycosis and conidiobolomycosis. Oral dosing of 1ml (three times a day) of a 1g/ml saturated solution of KI is slowly raised to 12-15ml daily. This is continued for 4-6 weeks after disappearance of the lesions.
Fungi - the drug is active against.
Sporothrix schenckii, Basidiobolus spp. and Conidiobolus spp.
Metabolism distribution and excretion.
Iodine absorbed from the gut is taken up rapidly and preferentially by the cells of the thyroid gland. Hence the need to take treatment several times daily to provide enough circulating KI to directly affect the fungus being treated. In circulation it is excreted by the kidneys easily.
Drug/ Drug interactions
There are numerous drug interactions with KI, especially with drugs such as captopril and enalapril as well as potassium sparing diuretics such as amiloride or triamterene or aldosterone antagonists leading to raised blood potassium, which can affect the heart rhythm. View drug interaction database.
Common side effects of KI include cold symptoms, acne, nausea, vomiting and stomach pains, which may severe enough to require temporary reduction of dosing, hence the slow build up in treatment dose. KI can also cause sialadenitis or parotitis, allergic reactions and rashes. At maximal doses (and sometimes at much lower doses) side effects of KI include fever, weakness, unusual tiredness, swelling in the neck or throat, mouth sores, skin rash, irregular heartbeat, numbness or tingling of the hands or feet or a metallic taste in the mouth. Potassium iodide should not be taken in pregnancy.