IngredientsThe ingredient most commonly marketed as "purified silver" in the dietary supplement context is colloidal silver — a suspension of sub-microscopic silver particles dispersed in a liquid medium, almost always purified or deionized water. Colloidal silver is made up of miniscule particles of silver that are suspended in liquid. The term encompasses a spectrum of preparations that vary considerably in their physicochemical characteristics. In scientific and regulatory literature, the key forms are:
Chemical identity: The elemental symbol for silver is Ag (from the Latin argentum), atomic number 47, CAS number 7440-22-4. Products marketed as purified silver are typically described as consisting of deionized water and a suspension of 99.99% pure silver particles. Silver is a metallic element that is mined as a precious metal, with various industrial uses including jewelry, silverware, electronic equipment, dental fillings, photographic processing, and disinfecting water. It has no botanical origin; it is a naturally occurring inorganic element found in the earth's crust in mineral form.
Silver has no biological role, and it is particularly toxic to lower organisms. Silver has no known functions or benefits in the body when taken by mouth, and it is not an essential mineral. Commercial supplement concentrations vary widely; one studied commercial colloidal silver solution had a high concentration of 1,000 mg/L, stabilized with pectin in distilled water. Other commercially analyzed products contained colloidal silver at concentrations of 15, 30, 55, 80, and 125 mg/L.
Colloidal silver products are often marketed as dietary supplements to take by mouth. These products also come in forms to use on the skin. Nasal sprays have also been developed and studied for sinusitis applications.
Silver has a long and intriguing history as an antibiotic in human health care. Silver has a long history of medical use, dating back to ancient civilizations where it was valued for its antimicrobial properties. The earliest recorded application of silver for antimicrobial purposes can be traced to ancient Greece, where silver vessels were used to preserve drinking water and wine. While its antimicrobial effects were empirically recognized, the underlying mechanisms remained unknown at the time.
The history of the use of silver dates back to ancient times. First, it was used as jewelry, for body piercings, currency and food handling. The earliest medical use of silver was for water storage to prevent spoilage and keep it fresh for drink. The Phoenicians kept water, wine, and vinegar in silver pots to prevent them from spoilage. Roman soldiers carried silver containers to store water and food supplies during campaigns, exploiting the empirically observed preservative effect of the metal.
In the 19th century, silver found its way into formal medical practice. Silver nitrate became a widely used antiseptic for wound care and was also employed to prevent ophthalmia neonatorum in newborns. Silver's role in healthcare gained prominence in the 19th century as an antiseptic agent. Surgeons like J. Marion Sims in the United States adopted silver wire sutures in the 1840s for gynecological procedures, noting fewer infections than with silk or catgut alternatives. In Europe, Carl Credé introduced silver nitrate eye drops in 1881 to prevent gonococcal ophthalmia neonatorum, a leading cause of newborn blindness. This method drastically reduced infection rates and became a standard practice worldwide.
The antimicrobial properties of silver were scientifically confirmed as early as in the 19th century, which laid the ground for the application of metal and its compounds in medicine. During World War I, silver compounds were used to prevent infections as antibiotics were not known then. As a standard solution, silver (I) nitrate was used, which was later replaced with sulfadiazine ointment.
In 1889, M.C. Lea synthesized citrate-stabilized silver colloids, marking the first documented production of colloidal silver. This formulation, which yielded AgNPs with a diameter of approximately 10 nm, demonstrated antimicrobial activity, paving the way for medical applications. By the early 20th century, before antibiotics dominated, silver formulations like colloidal silver and silver salts treated eye infections, chronic wounds, and mucous membrane conditions. Products such as Protargol and Argyrol addressed gonorrhea and prevented blindness. The 1916 Merck Index listed 18 silver-based medicines, underscoring its status as a pre-antibiotic staple.
World War I soldiers took silver leaf into battle to help fight infection if they were injured in the trenches, and silver was increasingly used to treat common ailments such as sore throats and tonsillitis. Silver first gained regulatory approval for use as an antimicrobial agent in the early 20th century, but its usage diminished with the introduction of antibiotics in the 1940s. With the discovery of antibiotics and sulfonamides, the interest in silver-containing drugs temporarily decreased, but is now gaining new momentum.
Silver nitrate persisted for neonatal eye prophylaxis, and silver sulfadiazine (SSD) cream, developed in the 1960s, became essential for burn care by combining silver's antimicrobial action with a sulfa drug. Topical silver has gained popularity once again, principally in the management of open wounds. This has been largely due to the spread of methicillin-resistant Staphylococcus aureus (MRSA) and the resultant reduction in first-line antibiotic prescribing. Silver has been developed for use in water purification, wound care, bone prostheses, reconstructive orthopaedic surgery, cardiac devices, catheters, and surgical appliances.
Unlike botanical supplements that contain complex mixtures of phytochemicals, purified silver is a single-element preparation. Its pharmacological activity derives from the behavior of silver in biological environments.
The antimicrobial action of AgNPs is linked with four well-defined mechanisms: (1) adhesion of AgNPs onto the surface of cell wall and membrane, (2) AgNPs penetration inside the cell and damaging of intracellular structures (mitochondria, vacuoles, ribosomes) and biomolecules (protein, lipids, and DNA), (3) AgNPs-induced cellular toxicity and oxidative stress caused by generation of reactive oxygen species (ROS).
Membrane disruption: Silver ions can easily adhere to the cell wall and cytoplasmic membrane as they are more closely related to sulfur proteins and also due to electrostatic attraction. The bacterial envelope is disrupted because when silver ions attach to the cell wall or cytoplasmic membrane, it enhances the permeability of the cell and ultimately leads to cell disruption.
Respiratory chain inhibition: When free silver ions are taken up by cells, they deactivate respiratory enzymes, generating reactive oxygen species interrupting adenosine triphosphate (ATP) production. ROS is the principal species that provokes DNA modification and cell membrane disruption. Ag⁺ ions are known to cause dysfunction of the respiratory electron transport chain by uncoupling it from oxidative phosphorylation by inhibiting respiratory chain enzymes.
DNA damage: Another critical antimicrobial mechanism of AgNPs is their ability to interact with bacterial nucleic acids. AgNPs can directly bind to bacterial DNA, causing structural distortions that hinder replication and transcription. Ag⁺ ions intercalate between purine and pyrimidine base pairs, disrupting hydrogen bonds between the complementary DNA strands. Additionally, AgNPs induce structural changes in DNA, causing it to transition from a relaxed to a condensed state, which ultimately inhibits its ability to replicate.
Protein and enzyme interaction: Nanoparticles can break and cross the cell membrane, altering its structure and permeability, and can also enter the cell where AgNPs have an affinity to interact with sulfur or phosphorus groups present in intracellular content such as DNA and proteins, altering their structure and functions. They may also alter the respiratory chain in the inner membrane by interacting with thiol groups in enzymes, inducing reactive oxygen species and free radicals, generating damage to intracellular machinery and activating the apoptosis pathway.
Biofilm disruption: Various studies have demonstrated that AgNPs cause oxidative stress, protein dysfunction, membrane disruption, and DNA damage in bacteria, ultimately leading to bacterial death. AgNPs have also been found to alter the adhesion of bacterial cells to prevent biofilm formation.
AgNPs possess broad-spectrum biocidal potential against bacteria, fungi, viruses, and Mycobacterium, in addition to exhibiting synergistic effects when combined with certain antibiotics. It was shown that the silver (I) cation has bactericidal, antiseptic, anti-inflammatory and astringent effects. It is a natural bactericidal metal that is effective against 650 species of bacteria with low reported resistance.
Silver nanoparticles have attracted attention as broad-spectrum antiviral agents due to their unique physicochemical properties and ability to target multiple stages of viral infection. Research has highlighted their efficacy against clinically relevant enveloped viruses such as influenza, herpes simplex, hepatitis B, and coronaviruses. Studies indicate that AgNPs exert their effects through direct interactions with viral particles, inhibition of viral adhesion, and entry into host cells with disruption of viral replication.
Silver is absorbed into the human body and enters the systemic circulation as a protein complex to be eliminated by the liver and kidneys. Silver metabolism is modulated by induction and binding to metallothioneins. This complex mitigates the cellular toxicity of silver and contributes to tissue repair. Following oral ingestion specifically, silver compounds are mostly deposited in the liver and spleen, but can also be found in skeletal muscles, skin, and brain. In body fluids, silver binds to high molecular weight proteins as well as metallothionein, and is excreted mainly through biliary pathways.
The route of exposure modulates biodistribution: oral administration mainly targets the liver and spleen, inhalation results in retention in the lungs and secondary deposition in the brain, while intravenous or subcutaneous routes lead to a more uniform systemic distribution but prolonged hepatic and splenic retention.
This is the area with the strongest scientific and clinical evidence for silver. At present, silver is re-emerging as a viable treatment option for infections encountered in burns, open wounds, and chronic ulcers. The gold standard in topical burn treatment is silver sulfadiazine (Ag-SD), a useful antibacterial agent for burn wound treatment.
Although Cochrane reviews concluded that the use of silver dressings for promoting wound healing and preventing infections is not supported by sufficient evidence, 26 randomized controlled trials (RCTs) incorporating 2,066 patients with positive results and a number of clinical and case studies found that silver dressings can promote wound healing and prevent wound contamination. A published randomized controlled trial (RCT) and two Cochrane reviews concluded that there is insufficient evidence to show that silver dressings improve healing rates. The overall effect of these reports has been to cast doubt on the wholesale adoption of silver dressings. However, in contrast to the negative findings of the RCT and two meta-analyses, the experience of many clinicians and other meta-analyses have confirmed positive effects of silver dressings when they are used appropriately. This disparity is based on the use of complete healing as an endpoint, which is insisted upon by regulatory bodies such as the Food and Drug Administration of the USA in clinical trials of this nature.
A 2017 meta-analysis cited in the peer-reviewed literature examined clinical studies on silver in wound management published from 2000 to 2015: a group of experts evaluated the clinical studies on silver in wound management published during the period 2000–2015, identifying 851 articles, of which 173 were included and categorized.
A concern with topical silver is its potential cytotoxicity: some studies have shown that silver has a cytotoxic effect on host cells, specifically fibroblasts and keratinocytes. Although the implications of this laboratory research for the clinical setting warrant further in vivo analysis, these data suggest that discontinuing silver agents once the wound bioburden has been reduced promotes healing. Recent findings indicate that silver sulfadiazine delays the wound-healing process and that silver may have serious cytotoxic activity on various host cells. Additionally, certain recent clinical studies in major burn centers have demonstrated the emergence of bacterial resistant strains — mainly Escherichia coli — to silver as well as to many antibiotics following the prolonged usage of silver-based dressings.
Evidence strength (topical wound/burn use): Moderate to strong for reducing wound bioburden and infection control; mixed for complete wound healing endpoints in RCTs. Most robust evidence is for silver sulfadiazine cream in burns. Evidence for colloidal silver specifically (as opposed to medical silver dressings) in wound care is more limited.
Rhinosinusitis is a highly prevalent disease (occurring in up to 30% of the population) where the mucous membranes in the sinuses get inflamed. It is usually triggered by an earlier respiratory tract disorder, such as bacterial or viral infections. In 12.5% of people, the disease becomes chronic, with inflammation of the sinuses lasting longer than 12 weeks, and in at least 10% of those patients, medical and surgical treatments do not resolve the symptoms.
Increasing (pre)clinical evidence has shown that AgNPs may effectively reduce biofilms and treat numerous microbial infections. As a result, four clinical trials assessing the use of AgNPs as topical antibacterial agents have been initiated in the last decade.
Despite the interest, regulatory reviews are not favorable for oral use: a few studies have evaluated the effectiveness of colloidal silver nasal spray to treat chronic sinus infections, but they did not demonstrate meaningful improvements.
Evidence strength (sinusitis): Preclinical evidence (in vitro, animal) is promising for biofilm reduction. A small number of clinical trials have been initiated; however, available human trial data have not demonstrated meaningful clinical improvements per NCCIH. Evidence is currently preliminary and insufficient to support a clinical recommendation.
A silver nanoparticle formulation designated Nowarta110 has been studied in a Phase I/II randomized controlled trial. 18 out of 28 patients treated with Nowarta110 presented complete clearance of their warts and the remaining ten patients showed between 20 and 80% decrease in their lesion dimensions. In the placebo group, only 5 out of 26 patients responded positively, with 2 presenting full recovery and 3 displaying between 10 and 35% decrease in their wart dimensions. Nowarta110 showed very low side effects, with only one minor pain event reported. Hence, topical Nowarta110 proved to be well tolerated and safe, as well as highly effective against recurrent and refractory plantar warts. The therapeutic efficacy of Nowarta110 will be further evaluated in a Phase III clinical trial.
Evidence strength (plantar warts): One Phase I/II RCT showing favorable results for a specific topical AgNP formulation. Awaiting Phase III confirmation. Promising but currently preliminary.
Extensive evidence demonstrates the potent antibacterial and antifungal properties of AgNPs, particularly their efficacy against common pathogens such as Staphylococcus aureus, Escherichia coli, and Candida albicans. In laboratory research, significant antifungal and antibiofilm activity of AgNPs was detected against all tested Candida auris isolates; MIC was <6.25 µg/mL, the range of MFC was from 6.25 to 12.5 µg/mL for all isolates.
Evidence strength (antifungal): Strong in vitro evidence against Candida species and other fungi. Clinical trial data in humans are lacking. Evidence does not yet support clinical use as a systemic antifungal.
Silver nanoparticles have attracted attention as broad-spectrum antiviral agents due to their unique physicochemical properties and ability to target multiple stages of viral infection. A comprehensive review highlighted their efficacy against clinically relevant enveloped viruses such as influenza, herpes simplex, hepatitis B, and coronaviruses. However, there is no clinical evidence supporting the use of colloidal silver to prevent or treat COVID-19.
Evidence strength (antiviral): Predominantly in vitro and mechanistic. No completed, published human clinical trials demonstrate efficacy against viral infections when silver is taken orally as a dietary supplement. The antiviral literature is dominated by cell culture and animal model studies.
Colloidal silver is sometimes promoted on the internet as a dietary supplement; however, evidence supporting health-related claims is lacking. It is taken as a dietary supplement, often promoted online for its supposed health benefits, though evidence supporting these claims is lacking. To date, no research supports the use of oral colloidal silver in the prevention, treatment, or cure of any health condition or disease.
Despite promoters' claims, silver has no known function in the body and is not an essential mineral supplement.
Evidence strength (oral systemic use): No human clinical trial evidence supports efficacy for any condition via oral supplementation. This is the consensus position of the U.S. FDA, NIH NCCIH, WHO, ECHA, and other national health agencies.
Laboratory and preclinical research has explored the potential of AgNPs to restore or enhance antibiotic activity against multidrug-resistant bacteria. Various mechanisms have been proposed and observed for the enhancement of antibiotic efficacy by AgNPs, including bacterial membrane disruption, interference with essential cellular processes, DNA damage, and ROS overproduction. These mechanisms place a significant energetic burden on bacterial cells, potentially overwhelming resistance mechanisms. This therapeutic potential is explored through the use of silver nanoparticles as sources for silver ion release. Recent studies have shown that controlled silver ion release enhances the efficacy of common antibiotics.
Evidence strength (antibiotic synergy): Predominantly in vitro. While results are scientifically interesting, this area has not yet translated into approved clinical therapeutics.
No universally recognized therapeutic dose of oral silver exists, as the FDA has previously issued warnings that colloidal silver is not effective or safe for the treatment of any condition. The following dosage information is drawn strictly from regulatory reference points and characterized research settings:
Much of the danger surrounding colloidal silver is the inability to know the exact concentration of actual silver in the solution and the silver particle size. The rate of systemic absorption of silver is highly variable and depends on the particle size and whether or not the silver is truly in an ionized solution or bound to a carrier molecule. In one sample of commercially available colloidal silver tested by the EPA, a concentration of 5 parts per million was found in one teaspoon of solution, with one ounce of this preparation containing 0.15 mg of silver.
In 1999, the Food and Drug Administration (FDA) ruled that colloidal silver products are not generally recognized as safe and effective. Since then, the FDA has not approved any new colloidal silver drugs on the market. Colloidal silver products marketed for medical purposes or promoted for unproven uses are now considered "misbranded" under the law without appropriate FDA approval as a new drug. There are currently no FDA-approved over-the-counter or prescription drugs containing silver that are taken by mouth. The FDA and the Federal Trade Commission have taken action against a number of companies for making misleading claims about colloidal silver products.
Multiple international agencies share this stance: the Food and Drug Administration (FDA), the European Chemicals Agency (ECHA), the World Health Organization (WHO), and national agencies have issued public statements discouraging oral use, citing the absence of demonstrated therapeutic benefits and the potential for cumulative toxicity.
Colloidal silver can cause serious side effects. The most common is argyria, a build-up of silver in the body's tissues causing a bluish-gray discoloration of the skin, which is usually permanent. Chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to deposition of silver metal/silver sulfide particles in the skin (argyria), eye (argyrosis) and other organs. These are not life-threatening conditions but are cosmetically undesirable. Historically, silver compounds were used as antiseptics before the introduction of modern antibiotics, but their uncontrolled internal administration is associated with toxic effects, most notably argyria — a permanent bluish-grey discoloration of the skin and mucous membranes due to silver deposition in tissues.
Colloidal silver can cause poor absorption of some drugs, such as certain antibiotics and thyroxine (used to treat thyroid deficiency). There is also some evidence that it can cause kidney, liver, or nervous system problems. Repeated or long-term exposure, even at low doses, can result in tissue-specific bioaccumulation and chronic toxicity. Silver nanoparticles (AgNPs) induce multiple toxic effects in human cell lines, strongly depending on particle size, dose, and exposure time. In human bronchial epithelial cells (BEAS-2B), exposure to 20 nm AgNPs at 10–50 µg/mL for 24 hours significantly increased reactive oxygen species (ROS) production, DNA strand breaks, and triggered apoptosis.
Marketing platforms often state that silver nanoparticles are naturally eliminated from the body after exerting their antimicrobial effect — an assertion that contradicts findings related to bioaccumulation and tissue retention. Unlike other heavy metals, there is no evidence that silver is a cumulative poison, but its levels can build up in the body tissues after prolonged exposure, leading to undesired effects. Silver compounds have been reported to be absorbed by 10–20% after ingestion, though most data come from animal studies.
Colloidal silver may interfere with the body's absorption of the following drugs: penicillamine, quinolones, tetracyclines, and thyroxine. These interactions are pharmacokinetic (absorption-based) rather than pharmacodynamic. This is of particular clinical relevance given that quinolones and tetracyclines are among the most commonly prescribed broad-spectrum antibiotics, and thyroxine (levothyroxine) is widely used for hypothyroidism.
While bacterial resistance to silver has been considered rare, certain recent clinical studies in major burn centers have demonstrated the emergence of bacterial resistant strains, mainly Escherichia coli, to silver as well as to many antibiotics following the prolonged usage of silver-based dressings. There is only one known case of a naturally silver-resistant bacterial strain — the Pseudomonas stutzeri strain, which naturally occurs in silver mines.
Silver allergy is a known contraindication for using silver in medical devices. Although uncommon, contact allergy to silver has been documented.
Pregnant women should never consume colloidal silver because it can cause developmental abnormalities in the fetus.
Many manufacturers do not provide information regarding nanoparticle size or recommended duration of use. Results indicate a potential toxicological risk due to estimated intake levels that may exceed safety thresholds, particularly in high-concentration products with insufficient labelling or unclear usage guidelines. Colloidal silver products vary widely in their composition and are usually labeled with false health claims.
Health conditions that Purified silver may help support.
Silver in various forms (silver sulfadiazine, nanocrystalline silver dressings, colloidal silver) has been the gold standard antimicrobial agent in burn wound care for decades. Silver sulfadiazine cream is the most widely prescribed topical burn treatment globally, with extensive RCT and systematic review evidence for antimicrobial efficacy, infection prevention, and wound healing support in partial- and full-thickness burns.
Body systems that Purified silver may help support.
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