Ozone therapy is an alternative medical treatment that introduces ozone or ozonides to the body. In April 2003, the United States Food and Drug Administration (FDA) prohibited all medical uses of ozone, "In any medical condition for which there is no proof of safety and effectiveness", stating "Ozone is a toxic gas with no known useful medical application in specific, adjunctive, or preventive therapy. In order for ozone to be effective as a germicide, it must be present in a concentration far greater than that which can be safely tolerated by man and animals."