The use of silver for its antimicrobial properties dates to ancient times when various cultures used it to retard spoilage and treat disease. During the first half of the 20th century, disinfectant uses of colloidal silver became widespread, while internal use to fight disease was practiced less frequently. With the advent of antibiotics, the various uses of this silver went into decline. Since the 1990s, though, colloidal silver has been promoted as an alternative medicine for a wide variety of conditions. It is used topically to fight infection, internally to combat diseases and as a disinfectant on a wide range of surfaces.
Disinfectant uses of this compound vary from water purification to coatings on urinary catheters to prevent bacterial infections. The antimicrobial action of colloidal silver is used to sterilize drinking water and is listed for this purpose by the World Health Organization. Silver’s recommended household uses include keeping damp towels and sponges free of bacteria and mildew, preventing odors in garbage containers, and stopping the spread of athlete's foot when sprayed in shoes. In addition, air conditioning units and heating vents sprayed with colloidal silver are thought to have less microbial growth. Research is being conducted to create antibacterial surfaces with impregnated silver particles.
Using the compound topically is said to help prevent infection in all types of skin wounds and conditions. Silver can be applied directly to insect bites, sunburn and rashes. Bandages sprayed with colloidal silver may prevent infection in burns and wounds. Infants used to receive silver nitrate drops in the eyes at birth to prevent neonatal conjunctivitis, but this substance is rarely used now. Gargling with colloidal silver is recommended for sore throats, tooth decay and mouth sores.
Internal uses of colloidal silver are promoted for diseases ranging from diabetes to acquired immune deficiency syndrome (AIDS). Clinical trials have not been conducted to evaluate colloidal silver’s efficacy for combating most disease, but user testimonials and anecdotal evidence support silver’s use to treat a wide variety of diseases and chronic conditions. Silver is being studied as a possible alternative to antibiotics for treating antibiotic-resistant strains of bacteria.
Colloidal silver contains tiny silver particles. Many commercial products called colloidal silver actually contain mostly silver ions in solution. Both silver ions and silver particles are antimicrobial, but when ingested, silver ions combine readily with chloride ions and lose their effectiveness. Ionic silver retains its antimicrobial properties when used as a surface disinfectant or when applied topically to clean skin.
In vitro studies have shown mixed results concerning commercially available colloidal silver’s effectiveness against microbes. Most information concerning the benefits of the various uses of colloidal silver preparations is anecdotal. Despite the lack of clinical and laboratory studies confirming the anti-microbial properties of commercial colloidal silver, it is promoted as effective against a wide range of bacteria, viruses and fungi.
A potential side effect of colloidal silver is the development of argyria. This is a condition where silver particles build up in the skin and other tissues, causing a blue or gray pigmentation. The blue-gray coloration might also appear in nails, gums and internal organs. Localized discoloration occurs from topical application of silver, while whole-body argyria develops with prolonged internal use of colloidal silver preparations. It is believed that long-term, high intake of silver is responsible for argyria.