Lugol's fluid is an aqueous solution of iodine and potassium iodide (accounting for approximately 2% by volume) and distilled water (97% of the remaining volume). It was developed in 1829 by Jean Lugol, a French physician. In Poland, Lugol's fluid did not become popular until 1986 due to the Chernobyl nuclear power plant disaster. It was administered to children and adults (in the form of liquid) to protect their health and lives from the negative effects of the radioactive cloud. The main purpose of Lugol's liquid was to protect the thyroid gland from absorption of the radioactive iodine isotope. Can Lugol's fluid be used today? Does it have any side effects on the body? Is it safe?