Prior to 1938, colloidal silver was widely promoted as a "cure-all".
It was the only product in those days that would kill fungus, virus and bacteria. Then long came antibiotics such as penicillin and sulfanilamide, medical use of colloidal silver ceased. From the 1990's there has been a renewed interest in colloidal silver and an alternative medicine treatment.

The FDA in the USA and the same relative authorities in other countries have made it illegal for any "cure all" claims that were advertised prior to 1938, to be made.

Some vendors say that "the darker the solution, the more potent the concentration of silver", implying that their dark brown, high ppm product is what you should purchase. It could be dangerous since any quantity over 350 micrograms (mcg) per day exceeds EPA standards for silver in drinking water. In analysis the product does support the labeled claims.

Colloidal silver is a powerful, natural antibiotic and preventative against infections. Acting as a catalyst, it reportedly disables the enzyme that one-celled bacteria, such as viruses and fungi need for their oxygen metabolism. They suffocate these organisms without corresponding harm occurring to human enzymes or parts of the human body chemistry. The result is the destruction of disease-causing organisms in the body and in the food.

Did you ever hear from some of the senior members in your family about putting silver dollars (before 1938) into milk to preserve its freshness? And this is milk that was kept at room temperature as in those days the refrigeration as we know it today did not exist.

The Food and Drug Administration today classifies colloidal silver as a pre-1938 drug. A letter from the FDA dated 9/13/91 states: "These products may continue to be marketed . . . as long as they are advertised and labeled for the same use as in 1938 and as long as they are manufactured in the original manner." Some of the manufacturing methods used before 1938 are still used today. An electro-colloidal process, which is known to be the best method, is used. There is only one company currently using a manufacturing process that is officially approved by the FDA.