Colloidal Silver: Trick or Treat?

Colloidal Silver – Trick or Treat?

The Merits of Silver Use in Healthcare

Welcome to the controversial world of colloidal silver (CS)! This area seems quite a mine field, with many passionate proponents and equally convinced opponents. Reminded me of researching the merit of coffee enemas. What gives in this case? Below is what I found out from the scientific literature. As always, readers are invited to draw their own conclusions. This may provide a jump start to your own research.

colloidal silverWhy Colloidal Silver?

What if there was a way to use antibiotics that create little bacterial resistance? What if one could use a natural element, not a synthetic drug, to affect wound healing? To detect and eliminate cancerous tumors without damaging surrounding tissues? To inactivate the HIV-1 virus?

Silver offers this potential.

What is Colloidal Silver?

Together with gold, silver is one of the oldest known noble metals, a naturally occurring element that has been used for at least 5000 years as currency, jewelry, in food handling, water purification, and, in recent decades, by the electronics industry (Barillo & Marx 2014). Everyone knows silver – but what’s a colloid exactly? A colloid combines two substances, one spreading throughout the other, to yield a mixture. Fog, smoke, mist, blood, milk, and clouds represent naturally occurring colloids. Here, silver particles (chemical notation: Ag) mix with pure water. The particles are evenly dispersed, non-soluble, and remain in suspension.

colloidal silver

Fig 1. The Tyndall Effect: true colloids scatter light, whereas clear solutions do not – an easy way to determine a colloid.

Shining a light through the dispersion produces the Tyndall effect (Fig. 1): scattering of light by minute particles in its way, resulting in a visualization of the light beam itself (think car headlights in fog). This easily distinguishes a true colloidal dispersion from a clear solution, where the light beam shines through without becoming visible.

Colloidal silver supplies silver in minute form as nanoparticles (a nanometer, nm, is a billionth of a meter, or 0. 000 000 001 m). In other words, they’re very small, invisible to the naked eye. Some cell organelles are even larger in diameter (eg ribosomes, 20 nm; nuclear pores, ~5 nm). Nanometers describe the realm of molecules and atoms – a very tiny scale indeed).

Applications of Nanoparticulate Silver

Medical uses of nanoparticles include targeted drug delivery, genomics, biosensorics, detection of cancer cells and tumor mapping, immunoanalysis, pregnancy testing, diagnostics of viruses, fungi, and pesticides, among many more (Dykman & Khlebtsov 2011).

Silver compounds also feature in a variety of clinical tools, such as indwelling catheters, bone prostheses, surgical sutures and needles, cardiac & dental implants, surgical textiles, or filters in hospital water supplies to prevent Legionella infections (Lansdown 2006, Barillo & Marx 2014).

colloidal silver - trick or treat

Fig 2. Silver labeled (black dots) mouse brain cell (red). A synapse from another, vesicle filled cell (blue) targets the labeled cell. ©Katrin Geist

Research widely applies nanoparticles of gold and silver to visualize specific tissues (labeling). Figure 2 shows an image I took of mouse brain cells. Both gold and silver were used to label specific target cells. Due to its electron density, metal readily shows up as black dots under the electron microscope. Notice the scale bar at 1000 nm (1μm).

Today, the marketplace offers more than 1300 nanotechnology-enabled consumer products, with nanoscale silver in various forms representing about a quarter of them (Munger et al. 2014). In 2012, more than 20 FDA-approved diagnostic or therapeutic nanotechnologies found clinical use, with c. 250 more in development (Dreaden & El-Sayed 2012). In 2014, the global nano-medicine market was valued at $248 billion and is projected to grow to $528 billion by 2019 (Evers 2015).

Popular Uses for Colloidal Silver

According to countless websites, CS is purported effective against >650 different pathogens (bacterial strains and viruses). Looking at random websites and testimonials speaking to the benefits of CS, people have found it useful for colds, viral infections, ear aches, dermatitis, arthritis, cat scratches, mouth ulcers, sore throat, tooth ache, eye infections, fungal infections on the skin, ringworm, burns, pneumonia, yeast infections, bronchitis, herpes, sinus infections, acne, digestive health, detoxification, Epstein Barr Virus, Chronic Fatigue Syndrome, pet health, asthma, heart burn, ulcers, macular degeneration, HIV, Crohn’s Disease, gallbladder disease, bad breath, bug bites, canker sores, chicken pocks, congestion, Lupus, fibromyalgia, diabetes, leprosy, kidney disease, liver disease, Malaria, MRSA, cysts, acid reflux – the list continues.

When compared to the available technical literature, however, a noticeable gap between the anecdotal evidence from online sources and the reported and researched data on CS benefits becomes apparent. We will revisit this discrepancy later.

colloidal silverSilver Use Through Time

Ionized silver (Ag+) exhibits antimicrobial properties, a trait Western medicine has taken advantage of for more than 200 years, particularly in wound dressing. Medicinal use of gold and silver dates back thousands of years across many cultures, however.

The ancient Ayurvedic remedy “Rajatbhasma” contains silver (Rai et al. 2016). Alexander the Great (335 BC) used it to purify water and drank from a silver cup. The Greeks, Romans, and Asians stored water in silver vessels to keep it fresh. The Roman book of medicines included silver. They also used silver nitrate, a substance still in use today.

In the Middle Ages, silver nitrate (Lunar Caustic) featured as remedy for nervous disorders; epilepsy was treated with it until the late 19th century (Fung et al. 1996). Asian cultures applied silver foil in wound dressing. In 16th century Europe, a royal battlefield surgeon used silver clips for facial reconstruction, while across the pond, in the late 1800s USA, Dr Georgia Arbuckle Fix inserted a flattened silver coin into a skull to successfully close its injury (don’t you just love the good doctor’s last name was Fix?!). Settlers traveling west during that time also placed silver coins in their water barrels to repress bacterial and algal growth.

Meantime, in Germany, physicians successfully used silver nitrate as antibiotic in neonatal eye care. The US adopted the method and recommended silver nitrate up until the late 1970s, when it became unavailable (Barillo & Marx 2014). Colloidal silver proteins featured in cold remedies until the middle of the 20th century (Fung et al. 1996).

In the 1960s, with the space race under way, NASA funded a study which concluded that a silver ion concentration of 50 parts per billion was sufficient to suppress microorganisms, thus keeping their astronaut’s water clean while in orbit (Barillo & Marx 2014). Apollo missions used a combination of chlorine, iodine and ionic silver to purify water, and it’s still applied in today’s space shuttles and the International Space Station (Barillo & Marx 2014), as well as by Swiss ski resorts, German breweries, soft drink bottlers, ships, drilling rigs, and some airlines. No toxicity of silver-treated water has ever been reported (Dolara 2014).

More recently, the health promoting effects of silver found their way into consumer products like washing machines, clothing, bedding, toothpaste, shampoo, toys, humidifiers, nursing bottles, or refrigerators, with manufacturers declaring sanitizing and deodorizing effects through germicidal activity (Barillo & Marx 2014, Kim et al. 2010). Various products around the globe offer silver: as silver-coated mints (‘Jintan’) in Japan, as silver-citrate complexes in health food additives in Florida, in domestic water purification cartridges in the U.S. (‘Brita’), and as supermarket-available colloidal ‘silver-gelatinate’ for washing salad vegetables in Mexico (‘Microdyn’). Jintan, for example, is specifically sold for ‘heartburn, nausea and vomiting, motion sickness, hangover, dizziness, bad breadth, choking, indisposition, and sunstroke’ (label information) (Silver 2003).

Other contemporary uses of silver include photography, soldering, and electronic equipment. The most common human exposure to silver occurs with dental amalgams, which contain 35% Ag. Its release (leaching) into the body apparently has never been measured (Silver 2003). Sea food may also contain appreciable silver levels.

Silver in Human Physiology

Silver is not a trace metal and serves no known mandatory roles in human physiology. That said, our body usually contains traces of silver, mostly taken up from the environment, where natural weathering of rocks releases it into water and air, or from human activities, such as cement manufacture or burning fossil fuels (Marx & Barillo 2014).

Typical silver levels in healthy individuals show a blood concentration of <2.3 μg/l and a urinary excretion of 2 μg/day. Daily silver uptake from dietary sources is estimated at 27-88 μg/day (Marx & Barillo 2014).

Silver absorbed into the human body accumulates in a transitory fashion in the liver, kidney, brain, lung and bone marrow with minimal or no toxic risk. Bone and teeth show little silver uptake (Lansdown 2006). Orally ingested particulate silver offers low systemic bioavailability (Hadrup & Lam 2014, Smock et al. 2013) and is mostly absorbed by the small intestine. The GI tract also represents its main excretion route (particulate silver), together with the liver and kidneys (ionic silver).

It seems as though very little particulate silver crosses the intestine into the blood stream, and that silver mostly travels around the body in ionic form (Munger et al. 2014a). Approximately 10% of inorganic silver is absorbed (Dolara 2014). In burn patients, silver from applied wound dressings (silver sulfadiazine) cleared completely within 28 days (Marx & Barillo 2014).

The Fine Line: Ionic vs Colloidal Silver

When reading websites and some of the literature, colloidal silver and ionic silver are often used interchangeably, but there is a difference. Ions represent the active form of silver, whereas particulate (metallic) silver is inert. It may release ions under appropriate conditions, however.

When atoms give off an electron (oxidation), they assume a less stable state. Silver exhibits three oxidation states, Ag+, Ag2+, and Ag3+, each subsequently losing another electron. Only the first, Ag+, is sufficiently stable for use as antibiotic, the others are too highly reactive, and thus short lived.

Silver compounds ionize in water and biological tissues – they release Ag+ to some extent (Lansdown 2006). Thus, orally taken CS also delivers silver ions, together with nanoparticles (Munger et al. 2014a), and the mechanism of action likely always involves silver ions.

Metallic silver (Ag) is inert and without biocidal activity. Your silverware or jewelry won’t externally affect your health – swallow that tongue piercing, however, and it becomes a source of silver ions as it passes through your digestive tract. Given the low silver ion concentrations known to affect microbiota – 1 part per million or less (Marx & Barillo 2014) – this actually could affect your intestinal flora. One would probably have to swallow lots of jewelry to feel any effect, however – so rest easy while awaiting its natural reappearance.

Silver Biochemistry ~ How it Works

To exhibit any antimicrobial effect, silver needs to occur in free, ionic form (Ag+). Bound to molecules (as complex chelates or precipitates), silver loses its biocidal capacity. Kind of like not being able to catch a volleyball when already holding one. You’re not free to accept another, and thus unavailable to interact any further. Ionic silver is highly reactive and readily combines with inorganic substrates (eg chloride), organic acids, negatively charged proteins, DNA, and RNA (Marx & Barillo 2014). Which brings us to how silver exerts its antimicrobial effect.

In essence, silver (ions) bind to cell surface receptors of bacteria, yeasts, and fungi. While the exact mechanism of action remains unclear, four possible ways are suggested, and they all include microorganisms accumulating enough silver until a lethal concentration is reached: 1) Silver blocks and eventually shuts down vital enzyme systems; 2) Silver causes a cell wall or membrane to rupture or leak; this also potentially interferes with concentration gradients between the cell and its environment and may hinder nutrient uptake; 3) Silver directly causes DNA mutations in bacteria (their DNA is not protected by a surrounding nucleus, as in our cells); 4) Silver forms free radicals that cause havoc within the cell by damaging vital structures and molecules, eventually leading to its demise.

While silver resistance can occur, and some resistant bacterial strains have been isolated from wounds (Lansdown 2006), it is rather uncommon, compared to conventional antibiotics. Silver resistant strains are also quite difficult to create in the laboratory, perhaps owing to the simultaneous action of multiple mechanisms, rather than only one single pathway (Marx & Barillo 2014, Barillo & Marx 2014).

Silver is a powerful broad-spectrum antibiotic that even kills bacterial strains that developed resistance otherwise, such as Providencia stuartii (occurs in burn wounds) or MRSA (Berger et al. 1976, Lansdown 2006, Lara et al. 2010). Most pathogens die at a dose of 5-40 ppm (Marx & Barillo 2014).

In dentistry, Cai & Lu (2008) reported the clinical effect of a colloidal silver gelatin sponge on preventing complications of tooth extraction. The incidence rate of bleeding, infection, pain, swelling, and dry socket after tooth extraction was significantly lower (P < 0.05) in the test group compared to the control group.

Exciting research regarding the antiviral activity of nanoparticulate silver comes from Mexico, where scientists proposed its mechanism of action against HIV-1 strains. Silver nanoparticles inhibited the initial stages of HIV-1 replication by preventing its attachment to host cells (Lara et al. 2010). Antiviral effects were found for 7 viral families (Rai et al. 2014), specifically against monkeypox virus (Rogers et al. 2008), hepatitis B virus (Lu et al. 2008), respiratory syncytial virus (Sun et al. 2008), herpes simplex virus type 1 (Lara et al. 2010), and others. For a detailed review, see Rai et al. (2014), who comment:

Silver nanoparticles have shown antiviral efficacy against several viruses […], therefore silver nanoparticles provide the opportunity of developing broad-spectrum antiviral drugs, […] since they might be of sure benefit when facing unknown viruses or viruses for which we lack specific antivirals.

And it doesn’t stop there.

Nanoparticles in Cancer Therapy: The Silver Bullet – as Good as Gold?

While almost a century ago CS as intravenous infusion (up to 30 mg per single dose) has been tried on patients with inoperable cancer, and no clinical improvements noted in five cases (Stone et al. 1930), modern approaches offer more exciting possibilities.

The resonant absorption properties of metallic nanoparticles result in strong, highly localized photothermal heating upon laser illumination, an effect that can be exploited to induce cancer cell death and tumor remission. The light scattering properties can be utilized for contrast enhancement in bioimaging. These two inherent properties of nanoparticles can be combined for integrated diagnostic imaging and therapeutics.”

(Lal et al. 2008)

Photothermal therapy (see Box 1), a newer form of cancer treatment first applied in 2003 (Dykman & Khlebtsov 2011), involves gold nanoparticles with subsequent light exposure. The resulting heat irreversibly damages and kills tumor cells.

colloidal silver

Box 1. Plasmonic Photothermal Therapy: a promising new approach to treat cancer with nanoparticles and light in a localized manner.

Some animal experiments (mouse model) revealed a greater success rate for nanoparticles directly inserted into the tumor, compared with their systemic administration. A light exposure of only 10 minutes resulted in complete tumor resorption in >50% and 25% of animals at two weeks, respectively (Dreaden & El-Sayed 2012).

Another exciting report comes from O’Neal et al. (2004) who systemically delivered nanoparticles to mice with artificially induced tumors; after allowing 6h for the particles to reach and accumulate in the subcutaneous tumor, it was irradiated with laser light for 3 minutes. The amazing result: “Tumor size and animal survival were monitored for 90 days following treatment. Within 10 days of nanoshell treatment, complete resorption of the tumor was observed. At 90+ days post-treatment, all mice remained healthy and free of tumors.” The control group fared less well, with tumors expanding rapidly.

Stern et al. (2008) examined the efficacy of laser activated gold nanoshells on tumor ablation in a human prostate cancer model in mice. In one experimental group, they observed complete tumor deletion at 21 days, concurrent with a histological tissue evaluation confirming complete tumor death. A well circumscribed eschar formed over the laser treated region by day 1. It fell off by day 21, revealing normal healthy skin. The authors conclude: “These observations reinforce the concepts of selective accumulation of GNS [gold nanoshells] at tumor sites and the benign nature of NIR [near-infrared] laser treatment in the absence of a concentrated nanoshell deposit [= no harm from irradiation in tissues which did not absorb nanoparticles].

Clinical trials were carried out for targeted cancer drug delivery. Gold nanoparticles (27 nm diameter) increased drug delivery/ patient tolerance three fold compared to the drug alone (Dreaden & El-Sayed 2012).

In case you’re wondering: silver also has its use in these technologies. Gold, silver, platinum, palladium, and others fall into the category of noble metal plasmon-resonant particles – where metal surfaces display a collective oscillation of free electrons when excited by appropriate light frequencies (Schrand et al. 2008). The very effect nanotechnology exploits to visualize tissue (increased contrast through light scattering) or kill tumors (light absorption and subsequent conversion to intolerable heat and thus tumor lysis).

In 2010, Franco-Molina et al. published a paper in the Journal of Experimental & Clinical Cancer Research concluding that “[…] colloidal silver might be a potential alternative agent for human breast cancer therapy.” These results come from human cell lines, not a clinical trial, and show that colloidal silver induced dose-dependent cell death in breast cancer cells, without affecting the viability of normal control cells. The dose used ranged between 3.5 and 14 ng/ml (the LD50 and LD100, respectively). LD50 = lethal dose at which 50% of cells die

Adverse Effects of Silver Exposure

Silver or silver sulphide deposits in living tissues rarely cause toxicological or physiological concern (Lansdown 2006). Silver in any form is not thought to be toxic to the immune, cardiovascular, nervous, or reproductive systems (Drake & Hazelwood 2005). It appears benign: silver is no skin or eye irritant, nor a mutagen (Marx & Barillo 2014).

The most common effects associated with prolonged silver exposure concern the development of a characteristic, irreversible pigmentation of the skin (argyria) and/or the eyes (argyrosis). The affected area turns bluish-gray or ash gray (Drake & Hazelwood 2005). Sun exposure enhances the effect, as light reduces silver compounds to metallic silver (Ag), which then aggregates in tissues and may oxidize to other silver compounds causing skin discoloration from the accumulation of silver particles or silver sulfide mostly in skin, conjunctiva, nails, or gums (Lansdown 2006). While unpleasant, argyria appears mostly a cosmetic concern, without known knock-on health effects. It is usually caused by excessive dosage and long-term use (Dolara 2014).

colloidal silver

Paul Karason, “The Blue Man” and an example of what argyria, a gray or blue skin complexion resulting from silver consumption (large doses over prolonged periods of time), looks like.

One such example was a 38 year old man who made his own CS (450 ppm) and consumed about 450 ml 3x a day for 10 months to ease arthritis. While his condition improved, his skin turned gray and he discontinued using CS (Wadhera & Fung 2005, see images here). Another rather extreme example comes from Paul Karason (on left), the “Man Who Turned Blue”, who took homemade CS in large amounts for a prolonged time. His story exemplifies the social repercussions people may face as a consequence of a blue skin complexion. This, rather than other physiological knock-on effects, may represent the most severe impact of argyria to an individual. Paul’s is the most extreme example I have seen. Theoretically, silver can be deposited in any tissue and has been found in brain, liver, kidneys, eyes, and bone marrow (Lansdown 2006), with longer retention times in brain and testes in rats (Hadrup & Lam 2014).

By and large, however, argyria seems fairly uncommon (White 2003). According to a 1973 submission to the FDA, the medical literature reported 365 cases between 1802 and 1951 (Fung & Bowen 1996). In his review, Dolara (2014) summarizes reports of silver intoxication from papers published after the year 2000, where “argyria was documented in a child of a vegan family supplemented with microelements; after prolonged use of a silver-containing product to boost the immune system; after assumption of silver-containing dietary supplement; for the therapy of diabetes, and following the continuous use of colloidal silver proteins as a self-prescribed remedy. A case of corticobasal degeneration of the brain and cardiomyopathy and left bundle block have been reported after colloidal silver ingestion”. While the latter two sound rather dramatic, when put in perspective, these 6 reports are few and far between, considering they sum up a 14 year period (of reported cases). The same applies to above FDA numbers, equivalent to 2.4 reported cases per year over 149 years. We also don’t know what formulations and concentrations people consumed. I believe most complications arise from overdosing and long-term exposure.

Toxicity of Silver Exposure

Despite the huge promise of nanotherapy and diagnostics and a growing multi-billion dollar industry, the assessment of any dangers of nanoparticle use only began in earnest about a decade ago (Khlebtsov & Dykman 2011), leading to the new field of nanotoxicology. A great deal is unknown about the interaction of nanoparticles with cells and organisms and a potentially resulting toxicity. Subchronic and chronic toxicity data on silver nanoparticles remain rare (Kim et al. 2010).

That said, experimental rats showed no obvious pathology after receiving acute or chronic doses of CS (silver protein suspension) for 12 and 40 days, respectively. Extrapolating these results to humans, a 70 kg person would have to ingest a very unlikely 4.2 g to match the rat’s highest dose (18 mg/ 300 g body weight) (USFDA 1999) – orders of magnitude above the maximum daily exposure reference dose of 350 μg per day for a 70 kg adult (0.005 mg/kg/day), as set by both the US Environmental Protection Agency (EPA) and the European Commission (Dolara 2014). The EPA critical dose (the amount that daily consumption should not exceed) for a 70 kg adult equals about 1 mg per day.

When looking on, most CS products contain between 5 and 30 ppm of silver. The relationship between ppm and amount of substance is: 1 ppm = 0.001 mg/g and 1 mg/g = 1000 ppm. In solution 1 g/l = 1000 ppm and 1 ppm = 0.001 g/l (or 1 mg/l). So, for a 10 ppm (= 10 mg/l or 10 μg/ml) CS product, a 70 kg person would have to take 35 ml (7 tsp) to reach the EPA reference dose, 100 ml to reach the critical dose, and, theoretically, 420 liters to reach above 4.2 g mark from the rat experiment. Thus, taking 1-3 tsp of 10 ppm CS a day for a limited time poses little risk, as it is well below the EPA reference dose (which pertains to silver uptake from all sources; remember, daily silver intake from dietary sources is estimated at 27-88 μg/day, and this varies with geographic region). 1 tsp of a 10 ppm CS solution contains 50 μg of silver.

colloidal silverMice supplied with CS in their drinking water at overdoses of 10 and 50-fold higher than manufacturer recommendations showed no changes in evaluated parameters (fertility, birth, tumor development) within a 12 month period (Franco-Molina et al. 2010).

Orally administered nanoparticulate silver was not toxic to guinea pigs at acute doses of up to 5 g/kg of body weight/day (Hadrup & Lam 2014).

Munger et al. (2014a) used 15 ml of CS solution (10 ppm and 32 ppm) with 60 healthy volunteers aged 18 – 80 years and found no relevant clinical impact of this dose after 2, 7, and 14 days of daily exposure.

Munger et al. (2014) conducted the first in vivo human assessment of cytochrome P450 enzyme activity from a systemic, orally ingested CS product. Cytochrome P450 is an important detoxification enzyme system in our body. On average, participants consumed 480 μg of CS per day (32 ppm formulation) for 14 days. The CS solution was a commercially available product with an average particle size of ~32 nm. This ingestion produced detectable blood silver levels, likely in ionic form (Munger et al. 2014a), “but no clinically significant changes in metabolic, hematologic [blood parameters], urine or physical parameters, and no significant effects on cytochrome P450 enzyme inhibition or induction activity” (Munger et al. 2014). These results link in well with a previous study by the same group, the first to “quantitate changes in human metabolic, hematologic, and sputum [mucus] morphology, and to monitor for changes in physical findings and organ imaging after exposure to a commercially available aqueous silver colloid nanoparticle oral formulation [American Silver LLC, Utah].” The authors concluded:”[…] oral exposure to these commercial nanoscale silver particle solutions does not prompt clinically important changes in human metabolic, hematologic, urine, physical findings or imaging morphology” (Munger et al. 2014a).

Part of some confusion around possible CS toxicity may stem from discrepancies between in vitro (petri dish) and in vivo (in live beings) study results, where CS impacted cell cultures negatively, yet no such effect surfaced when tested in vivo (Munger et al. 2014 & 2014a). Diverse methods of silver nanoparticle preparation, which profoundly influence their resulting physicochemical properties and surface chemistry, also pose a challenge to comparing study results (Munger et al. 2014). Other tests on healthy mouse bone marrow cells revealed no obvious detrimental effects of ionic silver (Berger et al. 1976).

Hadrup & Lam (2014) report a number of animal studies which showed negative effects on the GI tract (intestinal pigmentation), liver (> uric acid excretion), weight (loss), blood parameters, and the cardiovascular system. Many of these studies used silver particles in fairly high doses (eg 300, 500 or 1000 mg/kg body weight). The EPA critical dose for humans is 14 μg/ kg body weight, c. 1 mg total for a 70 kg person; the EPA reference dose is 5 μg/kg body weight. A laboratory mouse weighs about 20 g. Giving it a 500 mg/kg dose amounts to 10 mg total silver uptake – 10 times the critical dose amount for a 70 kg human. The lowest reported effect level [the smallest concentration to show an effect] from animal studies is 0.5 mg/ kg body weight/ day in mice (Hadrup & Lam 2014).

Some evidence suggests that ingested silver crosses the placental barrier (at 250 mg/kg – a very large dose, exceeding the EPA critical dose (14 μg/kg) by orders of magnitude); whether or not silver crosses the blood-brain barrier remains uncertain, tendency negative (Hadrup & Lam 2014, Terentyuk et al. 2009).

All up, three human in vivo/ ex vivo studies showed no significant or clinically relevant physiological changes in their subjects (Munger et al. 2014a, Smock et al. 2014, Munger et al. 2014). All used the same CS product. While this doesn’t mean that all available CS products are safe, especially when used in higher concentrations for prolonged periods of time, it provides grounds for the temporary, reasonable use of CS without ill effects. The authors conclude: “These studies provide the scientific, regulatory and healthcare industry a set of safety data on one single silver-engineered nanotechnology product. Furthermore, these studies were designed to offer a template for investigating other systemic nanoproducts into the future”.

Lastly, “consumers exposed to silver in textiles are expected to be at minimal risk. Silver is not absorbed through intact skin, even in moist areas, to any great extent” (Lansdown 2006).

Public Opinion vs Published Opinion ~ Colloidal Silver: Trick or Treat?

Is CS useful? Some respond with an emphatic “YES!”, while others put it down to the placebo effect and snake oil at best, while stressing inherent dangers of oral colloidal silver consumption (argyria). There has been a continuing battle between proponents of CS use for health and medical benefits and government agencies regulating claims and products for more than 100 years (Silver 2003). While some authors (eg Griffiths et al. 2015, Marx & Barillo 2014, Silver 2003, Fung & Bowen 1996), the National Center for Complementary and Integrative Health (NIH), and the US Food & Drug Administration (FDA) don’t hold CS in high regard, others report its potential and benefits (eg Rai et al. 2014, Neumayr et al. 2011, Lal et al. 2010, Franco-Moina et al. 2010, Cai & Lu 2008), a view backed by ample anecdotal evidence (websites, user testimonials & practitioner experience) to fill volumes. Interestingly, despite FDA regulation against over-the-counter selling in the US (USFDA 1999), a plethora of websites there sell CS, praising its many applications (the FDA rule does not apply to dietary supplements (Wadhera & Fung 2005)). A search on Amazon (10 Feb 2017) retrieved 710 results for “colloidal silver”. A Google search for the same term returned 1.7 mio websites.

The technical literature speaks to a fraction of the CS benefits reported by people online (but see here for a list of >100 papers). PubMed returned 413 papers for “colloidal silver”, Web of Science 6370, and Science Direct 26.870. The Cochrane Library lists 7 controlled trials. As with coffee enemas, the gap between Google search results (1.7 mio) and what returns from a literature search on science databases is wide. That said, hundreds or thousands of studies count for something and reflect a subject’s relevance. Thousands of studies equals millions of dollars invested. Clearly, there is substantial interest in silver and its medical applications, also owing to the rise of nanotechnologies.

In many instances, research results align with user experience, albeit often citing in vitro or animal models, as comparatively few human studies are available as yet. The medical literature I viewed reported benefit from silver use (including but not limited to CS) for the following:

  • warts & calluses
  • wound dressing (Lansdown 2006)
  • infection control (Lansdown 2006)
  • skin infections
  • bacterial & fungal infections associated with
  •      respiratory disease
  •      bone, joint, abdominal surgery sites
  •      prostheses
  •      cardiac devices
  •      eye lesions
  •      transplant surgery
  •      urinary catheters (silver coated catheters may reduce infection by up to 45%) (Barillo & Marx 2014)
  • pain relief in (Abboud et al. 2014)
  •      teeth
  •      skin graft donor sites
  •      thermal burns
  •      anal fistulae
  • respiratory problems in children (Damiani et al. 2011)
  • breast cancer cells in vitro (Franco-Molina et al. 2010)
  • antiviral effects (Rai et al. 2014), including HIV-1 (Lara et al. 2010)
  • reduction of dust mites in bedding (Neumayr et al. 2011)
  • reduction in complications after tooth extraction (Cai & Lu 2008)

Recently, a number of papers examined the physiological effects of orally administered CS from a commercially available product and found no clinically relevant impact in the parameters considered, including cardiac and abdominal MRI analyses (Munger et al. 2014a).

Going from online sources, it seems that CS use commonly occurs in some segments of the populace. Many swear by it, make their own at home, and take it for years without any noticeable side effects. Thousands if not millions of users worldwide attest to CS benefits. Given these numbers, together with the comparatively few reported cases from the literature, argyria or “turning blue” is extremely rare and many proponents who have taken CS for years still look and feel perfectly normal, experience benefits and no unwanted effects. Even the “Blue Man” himself continued using CS, albeit in lower doses than before, because it helped him with health issues.

As per efficacy, apart from countless healing stories, Lansdown (2006) offers a table of silver compounds used in a medical context. He refers to the ionizing capacity of colloidal silver preparations as “moderate to high”. This indicates to me a high probability of CS producing Ag+ ions, as also suggested in the literature (Hadrup & Lam 2014), and thus antimicrobial activity of orally consumed CS. Additionally, the small size of nanoparticles (<20 nm) increases their exposed surface area, compared to a relatively inert chunk of silver metal. An increased surface area translates into a higher release of ions: ionization of silver metal is proportional to the surface area of the exposed particle (Lansdown 2006). So the smaller the particle, the higher its ionizing capacity. And nanoparticles are very, very small!

Colloidal Silver and Cancer

In cancer therapy, nano silver or gold are combined with light to destruct tumor tissue. Nanoparticles are usually enhanced (attached to carrier molecules) to increase their time in circulation. Without this, the body would clear them from the blood stream fairly quickly, thereby reducing their chance to accumulate in a tumor mass. So, going from the technical literature, clinical CS treatment of cancer involves more than just swallowing nanonparticles. By exposing nanoparticles to laser radiation near their plasmon-resonant absorption band, it is possible to produce local heating of labeled cancer cells without harming surrounding healthy tissue, prompting tumor regression.

Some say (online) that colloidal silver heals cancer, without stabilizing CS or light excitation to heat the tumor. How exactly nanoparticles would achieve this on their own remains unclear to me – I can easily imagine that acquiring a certain level of particles would hamper cell metabolism. A function of bioavailability and absorption of particles by tumor cells and subsequent disruption of vital cellular processes. To explore this would take further (and certainly very interesting) reading and at this point exceeds the scope of this article. The closest I came to finding a hint of this in the select technical literature I read is Khlebtsov & Dykman’s 2011 review. They say: “The cellular uptake seems to be first important step, which may be affected by the particle geometry (size, shape, etc.) and its surface chemistry. […] Chan et al. discovered [the] crucial role of particle size in the efficiency of cancer cell uptake. Specifically, they showed that gold Nps [nanoparticles] conjugated with antibodies can regulate the size-dependent processes of binding and activation of membrane receptors, their internalization and subsequent protein expression. It has been found that 40 and 50 nm particles altered signaling processes most effectively, while other particles within 2–100 nm size range also demonstrated measurable effects. These findings mean that gold NPs can play an active role in mediating cellular response rather than serve as inert carriers” [emphasis mine] (Khlebtsov & Dykman 2011 ).

Terentyuk et al. (2009) tracked nanogold through the body over time (in rats): “[The] concentration of gold in tumors is elevated in comparison with surrounding normal tissue by means of passive delivery. We found two peaks of gold accumulation in the tumor. We speculated that the first spike in accumulation (30–45min) occurs because the concentration of gold in the bloodstream peaks. The second one (24hr) occurs due to passive accumulation of gold in the tumor tissue.” However, theirs were stabilized gold nanoshells (not plain colloidal gold).

Probably the most exciting paper investigating the potential of CS for cancer treatment is Franco-Molina et al. (2010), who studied a breast cancer cell line under CS exposure. Their protocol used  grenetine-stabilized CS, without subsequent light exposure. The result: “Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells […]”.

One wonders if above observations could form the basis of user-reported cancer regression from using plain CS?

Most Common Uses of Colloidal Silver

People commonly apply CS for colds/flu, viral infections, pink eye, sore throat, ear infections, in wound dressings/ skin health, as anti-inflammatory, and for sinusitis and pneumonia. As seen above, many other uses also feature in testimonial sections of websites.

What Colloidal Silver Product is Best?

While I’m no expert on this, from what I read these past weeks, particle size and shape play a crucial role in the cellular uptake of nanoparticles and their resulting effect (Rai et al. 2014, Khlebtsov & Dykman 2011). A size between 5-100 nm seems best, suspended in purified water at 10-30 ppm and generated at high voltage (vs colloidal silver solutions that add protein to stabilize silver or mostly contain ions, not particles (technically not a colloid at all)).

Given that little affects lots, I would opt for a 10 – 20 ppm product (not 500, 1000, or even 10000 ppm as I saw advertised online). Parts per million is really only a measure of how much (or rather little) silver a solution contains. You can use higher ppm products, just lower your intake accordingly. In the end, what matters is how much silver enters your body. You can drink 1 l of a weak solution or 1 ml of a very strong one. Same difference, except that high ppm formulations might contain added protein. According to some users and health practitioners, a variety to avoid. You might want to look into this for yourself and then decide. I prefer a plain colloid.

How Much Colloidal Silver Should One Use?

What follows are only guidelines deducted from the literature and websites. If you would like to treat an illness, please consult with a knowledgeable healthcare practitioner near you to see whether CS use would be appropriate or not.

My personal experience is rather limited and mostly pertains to cats, even though I used the spray the other day (once, 3x) to fend off what felt like an oncoming sore throat. Happily, nothing eventuated. This probably reflects one of the most common applications of CS.

As little affects lots, and as calculated above, I think that 1-3 tsp of a 10 ppm formulation a day is harmless. In line with this, some practitioners recommend 2 tsp 2x a day to prevent viral infections, for example. Dr Group advises 0.5 oz/daily on an empty stomach unless directed otherwise. Dr Axe recommends not using CS for more than 14 days in a row:

  • 2-5 drops applied directly to the skin
  • 1 eyedropper taken orally for immune support
  • 1-2 drops into eyes for pink eye
  • 1-2 drops can help disinfect any wound or sore by applying onto a Band-Aid
  • 5 drops added into a neti pot or directly sprayed into the nose
  • 5-10 drops can be applied vaginally or anally

Going from human studies, Munger et al. (2014a) used 15 ml (0.5 oz or 3 tsp) of 10 and 32 ppm solution without any indications of clinical adversity in his participants after 2, 7, and 14 days of daily consumption.

People also reported better results from repeated use (spray or tsp quantities), rather than only once a day. I would use CS occasionally when needed, and not habitually as “maintenance”. Some people regularly use way more than feels comfortable to me (eg 10 or 16 oz a day).

While online stories show that people happily consume CS in small and sometimes not so small amounts for years without noticing detrimental effects, the literature spoke to some measurable side effects in cell cultures (Munger et al. 2014a), animal models (Hadrup & Lam 2014, Terentyuk et al. 2009) and case reports of silver toxicity in humans (mostly argyria) (Fung & Bowen 1996). Sensible use is therefore recommended, as with anything. I believe it would take considerable amounts of CS to effect recognizable, undesirable outcomes, however.

When using CS, keep in mind that your gut bacteria are vital to your (or your pet’s) wellbeing, and that colloidal silver does not discern between the “good” and “bad” bugs in your system (contrary to what some websites claim). In my mind, it affects all of them, at only tiny doses. For this reason, I would not take CS for prolonged periods of time and either eat fermented foods (sauerkraut, kefir, etc.) or use probiotics to replenish the gut flora while on CS.

reconnective healing effects on petsColloidal Silver & Pets

Wanting to help my cat, most pet websites recommend 3 x 5 ml of a 10 ppm colloidal silver solution – in my mind, too large a dose. I started with a few drops on her food, and then 1-2 ml per day. This taught me that CS can be a great tool for quick relief – my cat healed up virtually over night from a drippy nose and raspy breath. Within 2 days, whatever this was resolved completely and she was back to normal. Since then, I always keep a bottle of CS in the cupboard. Many a stray cat has also benefited from this, especially with eye infections. They clear up quite nicely over night from adding a dropper of CS to their wet food the evening before. It may not always work this way, but is definitely worth a try! I’ve seen it many times by now. I don’t feel that adding CS drops to pet’s drinking water as “maintenance”, as I’ve seen people say online, is necessary, as it would continuously supply them with an antibiotic – something neither a pet nor a person really needs.


This article looked into the merits of silver use in healthcare, with emphasis on colloidal silver and technical literature sources.

Metallic silver and silver compounds are used widely in medical devices and health care products to provide antibacterial and antifungal action. Experience has shown that they are generally safe in use and effective in controlling pathogenic organisms. They do not achieve a ‘germ-free’ state in wounds, device-related infections or biofilm formation, however” (Lansdown 2006).

Colloidal (nano) silver, on the other hand, did inhibit biofilm formation in Candida albicans (Lara et al. 2015). A powerful broad-spectrum antibiotic effective against bacteria, viruses and fungi, it showed application in dental care, reducing dust mites, improving signs and symptoms in children with upper airway disease, action against HIV-1 (!) and human breast cancer cells in vitro, killing otherwise resistant organism like MRSA, bringing ineffective antibiotics back to life (enhancing their effect), and developing next to no resistance in microorganisms. Is this valuable? Of course it is. Especially when considering its good tolerability. When used appropriately, unwanted effects should rarely occur, apart from little available data on subchronic toxicities of nanoparticles in general. Nobody really knows. However, I am not concerned about the occasional, temporary use of CS, which has been shown to evoke no clinically relevant repercussions in available human studies.

I did not examine the anecdotal evidence in depth, as that’s readily available for anyone to read online (likely a worthwhile undertaking). Skimming through websites, however, the sheer volume of CS success stories and how many people swear by its use becomes apparent. While healing stories provide the least qualified evidence academically, it is difficult to ignore their large numbers, reported from around the globe. When people derive benefit, as with many other approaches we have little or no science for, their personal success lends credence to the method employed. Multiply that by 1.7 million website hits on Google and it’s clear that CS offers people something they consider valuable. For some, it’s a game changer altogether.

I will happily use CS as antibiotic or flu prevention when required. I’ll also continue to use it with pets, as observed results with cats were great so far. Curbing what felt like an oncoming cold was excellent, too.

As per ailments other than listed under the “Common Uses” section people reported good results for: I would most certainly look into it, should a need arise. At this point, I must point you to the myriad of websites out there – and a growing body of literature – to learn more. I’m sure it’s worthwhile!

~ The END ~

(Yes, really, you made it – congratulations!)


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Please note: this article does not constitute medical advice in any way and serves educational purposes only. Each person takes full responsibility for their wellbeing choices and decisions.

About the Author

Katrin GeistKatrin Geist, BA, MSc, combines her interests in consciousness, personal transformation, and natural healthcare as Reconnective Healing practitioner, speaker, and author. Her monthly “Healthy Living Newsletter” offers original articles like this one on relevant natural healthcare topics. Katrin has held international Reconnective Healing clinics in several countries and currently works from her New Zealand office in Dunedin.

To contact her for personal or remote sessions, send an email to, or call 0064 (0)21 026 95 806 (NZ mobile).

Katrin’s website and blog at also offer more information on Reconnective Healing and how it helps people regain and maintain their wellbeing – naturally and effortlessly: no pills, no needles, no side-effects. Trying this process may well be the best thing you ever did! No more than 3 sessions required to find out what difference this may make for you.

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Websites (lists dozens of available CS studies) (example of typical testimonials)

Colloidal Silver Solution



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