Common Name(s): Argent colloidal, Colloidal silver, Colloidal silver protein, Plata coloidal, Protéine d’argent, Silver colloid
Medically reviewed by Drugs.com. Last updated on Apr 21, 2023.
Colloidal silver has been investigated for use in wound healing and prevention of wound infection. Despite several purported uses, clinical trial data are lacking to recommend use for any indication, and the US Food and Drug Administration (FDA) has ruled that colloidal silver or silver salts for internal or external use are "not generally recognized as safe and effective and are misbranded."
Insufficient evidence exists to provide dosing recommendations for colloidal silver.
Avoid use. Silver may cross the placenta.
None well documented.
Oral ingestion of silver salts may cause GI irritation. GI bleeding, seizures, and skin discoloration reported in the literature are primarily due to silver toxicity (see Toxicology).
Argyria (purple-grey colored skin) is a recognized adverse outcome of exposure to colloidal silver. Hematological and neurological toxicities are rare but well documented.
Sliver is a metallic element (chemical symbol: Ag) with an atomic number of 47 and an atomic mass of 107.868 g/mol. Silver ions are dissociated from different salts and from particulate silver. Sliver nanoparticulate suspensions are typically mixtures consisting of silver ions, nanoparticles, subnano-sized particles, and aggregated nanosized or larger nanoparticles.Hadrup 2014 Colloidal silver is a suspension of submicroscopic metallic silver particles in a colloidal base, which results in an overall increased particle surface area.Franco-Molina 2010, CFR 1999
Dating from the Middle Ages, silver as the nitrate form ("lunar caustic") was used for the treatment of nervous disorders and epilepsy. Silver arsphenamine was used for treating syphilis.Fung 1996 Antibacterial activity of silver, reportedly described in ancient Greek texts, has resulted in widespread applications such as in prostheses, catheters, dental materials and textile fabrics, and in the management of skin and other infections.Fung 1996, Panacek 2006
Colloidal silver products are available as homeopathic remedies and dietary supplements. Purported uses include cancer, diabetes, arthritis, and many others. Colloidal silver preparations were formerly included in pharmaceutical texts (ie, prior to 1975); however, in 1999, the FDA ruled that colloidal silver or silver salts for internal or external use are "not generally recognized as safe and effective and are misbranded."CFR 1999
Colloidal silver generators are commercially available, and instructional videos demonstrating how to manufacture colloidal silver products at home are available via the internet. The basic premise is the use of electricity to reduce silver rods to the ionic form and suspend them in a liquid solution.Okan 2007
Colloidal silver consists of submicroscopic metallic silver particles suspended in a colloid base. Colloidal silver preparations contain silver ion concentrations of about 1 to 6 ppm (5 to 30 mcg) per dose; however, methods of production and silver content of marketed products can be highly variable.Fung 1996, Okan 2007, CFR 1999
Colloidal silver proteins are prepared by mixing silver nitrate, sodium hydroxide, and gelatin. The resulting mixture is diluted with water to achieve the desired concentration.Fung 1996 Techniques for synthesizing silver nanomaterials have been described.Panacek 2006, Tolaymat 2010
Uses and Pharmacology
Silver is considered nonessential to human physiology.Hadrup 2014 Limited clinical studies to determine a role for colloidal silver have been conducted; however, inconsistencies in the products used (ie, in silver particle size and content) exist.Duval 2019, CFR 1999
Silver binds to reactive groups of proteins, denaturing the protein (including enzymes such as lactate dehydrogenase and glutathione peroxidase) and causing precipitation. Silver has been noted to bind to sulfhydryl, amino, carboxyl, phosphate, and imidazole groups.Fung 1996, Tolaymat 2010
In vitro data
Limited in vitro studies suggest colloidal silver may reduce oxidative stress and induce apoptosis in human cancer cell lines.Franco-Molina 2010, Kim 2007, Lamb 2010 Conversely, a possible mechanism of silver colloidal solutions is the formation of intracellular free radicals.Duval 2019
Clinical studies evaluating colloidal silver for prevention or treatment of cancer are lacking. No evidence exists to support claims that silver deficiency is linked to impaired immunity and thereby a risk factor for cancer.Fung 1996
Animal and in vitro data
In vitro antibacterial and antifungal properties of colloidal silver have been reported.Panacek 2006, Petica 2008 Bactericidal effects of colloidal silver are considered to be inversely related to particle size (ie, smaller size having a greater antimicrobial effect) and may be related to influences on bacterial cell membrane or cell wall permeability, formation of free radicals, or alteration of the bacterial DNA replication process.Duval 2019, Panacek 2006, Tolaymat 2010
Colloidal silver irrigation has been evaluated in a chronic rhinosinusitis sheep model. Treatment with silver resulted in a significant decrease in Staphylococcus aureus biofilm biomass and in antibiofilm activity compared with saline control.Al-Asousi 2017 An in vitro study reported similar findings.Goggin 2014
Quality clinical studies evaluating the effects of oral colloidal silver in the prevention or treatment of infections are lacking.
In a randomized, crossover, controlled trial of patients with recalcitrant chronic rhinosinusitis (N=22), colloidal silver nasal spray did not demonstrate clinically meaningful subjective or objective improvements versus control.Scott 2017 Case series (N=5) demonstrate that applications of nano–colloidal silver in conjunction with chitosan bioactive as primary dressings in managing diabetic foot ulcers are safe and help increase wound healing rates; patients had slow healing rates at presentation.Nair 2018
Reviews of silver dressings and the role of silver nanoparticles in wound healing have been published.Okan 2007, Paladini 2019, Sterling 2014 A 2010 Cochrane review and meta-analysis found insufficient evidence to determine whether silver-containing dressings or topical agents promote wound healing or prevent wound infection.Storm-Versloot 2010
Insufficient evidence exists to provide dosing recommendations for colloidal silver.CFR 1999
Absorption of silver from the GI tract is estimated to be around 10%; excretion is very limited and occurs primarily via the biliary route.Fung 1996, Sterling 2014 Colloidal silver preparations have silver ion concentrations of about 1 to 6 ppm (5 to 30 mcg) per dose; however, methods of production and silver content of marketed products can be highly variable.Fung 1996, CFR 1999 Mild silver protein preparations contain 19% to 23% silver, while strong silver protein preparations contain 7.5% to 8.5% silver.Fung 1996
Pregnancy / Lactation
Avoid use. Silver may cross the placenta. Based on epidemiological studies, increased levels of silver in pregnant women have been reportedly linked to fetal abnormalities.Fung 1996
Case reports are lacking. In a prospective, single-blind, controlled, in vivo human study, no clinically important CYP-450 enzyme inhibition or induction activity was observed after oral ingestion of a commercial colloidal silver product over 14 days.(Munger 2015) However, an in vitro study evaluating cell viability reported that nanosilver may inhibit human microsomal CYP-450 activities, particularly CYP2C9, 2C19, and 3A4.(Lamb 2010)
Limited studies have reported equivocal findings with respect to the effect of oral silver on platelet aggregation. In vitro studies report enhanced platelet aggregation, while a study in healthy volunteers found no effect with daily consumption of colloidal silver for 2 weeks.Smock 2014
Oral ingestion of silver salts may cause GI irritation, and reports of hemorrhage and death exist in the literature.Fung 1996 Intravenous colloidal silver infusions are more toxic and are not supported by any clinical evidence (see Toxicology).Natelson 2019
The use of silver (as vitellinate or nitrate) for the treatment of conjunctivitis frequently causes chemical irritation.Silva 2008
Approximately 2% to 4% of silver absorbed from the GI tract is distributed to the skin and many other tissues (primarily in the GI tract, liver, spleen, and adrenals, with lesser amounts in the testes, muscle, and brain).Fung 1996, Hadrup 2014, Sterling 2014 Argyria, purple or purple-grey discoloration of the skin induced by silver, was reportedly first recognized in medical literature in 1791.Beutler 2016 Deposition of silver in the deeper epidermal and dermal layers of skin, and the resultant argyria, is permanent.Okan 2007
Hematological aberrations, including anemia, leukopenia, and neutropenia, have been described consequent to IV colloidal silver infusions. Apheresis and oral copper administration is suggested as a therapeutic option to address silver-induced anemia.Natelson 2019 Studies in rats report increased hematocrit, hemoglobin, and blood urea nitrogen values.Hadrup 2014
Neurological toxicity has been described, with silver possibly disrupting the blood-brain barrier.Fung 1996, Hadrup 2014, Naddaf 2019 A case report exists of fatal de novo myoclonic status epilepticus linked to consumption of colloidal silver for 4 months in an elderly man; silver accumulation in the brain was documented on autopsy.Mirsattari 2004 Another report of myoclonic seizures in a 75-year-old man describes a progressive neurodegenerative disorder related to consumption of colloidal silver over 4 years.Stepien 2009
Other reported manifestations of silver toxicity include toxic optic neuropathy, loss of optic choroidal signal, glomerular damage, proteinuria, and leukocytoclastic vasculitis.Docherty 2019, Fung 1996, Mohan 2019, Newlands 2018 Limited evidence suggests increased toxicity from silver may result from vitamin E or selenium deficiency.Fung 1996, Stepien 2009
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