colloidal silver
nounMedical Definition of colloidal silver
: a preparation consisting of silver particles suspended in liquid that is sometimes used as a dietary supplement
High doses of colloidal silver can turn the skin permanently blue. Though the silver is legal to sell as a dietary supplement, the Food and Drug Administration maintains it has never been tested to prove any therapeutic value.— Brigid Schulte, The Washington Post, 20 Jan. 2008