Colloidal silver

What it is

Colloidal silver is a liquid containing tiny particles of silver, sold as a dietary supplement. Laboratory analysis of commercial products found that most do not contain silver nanoparticles at all: in a study of 14 of the most popular products bought online, 70% contained only ionic silver, though eight of them were sold as 'colloidal silver'. Silver is not an essential mineral and has no known function in the human body when swallowed.

What the research says

There is no established use for swallowed colloidal silver. No clinical trial evidence supports the health claims made for it, and the one randomised human trial of a colloidal silver nasal spray found no benefit over saline. The US Food and Drug Administration ruled in 1999 that over-the-counter products containing colloidal silver or silver salts are not generally recognised as safe and effective and are misbranded. The documented consequence of regular use is argyria: silver deposits in the skin causing a permanent blue-grey discolouration, reported in case after case, including in a teenager after about a year of use.

Evidence grade: Not supported by the research.

What goes wrong

Laboratory analysis of popular commercial products found most contain only ionic silver, not the nanoparticles implied by the name. (Source 1)

• Lab study in cells, Low certainty.
• Size: 14 of the most popular colloidal silver products purchased from Amazon.
• Who: commercial products, not people.
• How long: not applicable.
• Result: 70% of products contained only ionic silver; eight of these were nonetheless promoted as colloidal silver; measured silver concentration was generally close to the label claim.
• Funding: not stated.

The results of this evaluation show clearly that 70% of the commercial products evaluated contain only ionic silver.

A 16-year-old developed permanent grey skin discolouration after taking colloidal silver for over a year for a resistant urinary infection. (Source 2)

• Case report, Very low certainty.
• Size: 1 patient.
• Who: a 16-year-old boy with a congenital urinary tract anomaly and recurrent infections.
• How long: colloidal silver taken for over a year.
• Result: bronze pigmentation of the face, most pronounced on the forehead and other sun-exposed areas; blood count, liver and kidney function and eye examination were normal; laser treatment offered for the cosmetic effect.
• Funding: not stated.

To overcome the infection, he took colloidal silver for over a year. The patient's disease improved, but a gray discoloration appeared on his skin.

Dermatologists report that the marketing of colloidal silver through complementary medicine is causing argyria to reappear as a clinical problem. (Source 3)

• Case report, Very low certainty.
• Size: 1 case, framed against a literature trend.
• Who: people using colloidal silver as complementary medicine.
• How long: recent years.
• Result: a described resurgence of argyria cases; sunlight has a catalytic effect so discolouration is worse on sun-exposed skin.
• Funding: not stated.

In recent years, the increasing trend of people towards complementary medicine and marketing the colloidal form of silver is causing a resurgence of cases of argyria.

NCCIH states that colloidal silver can impair absorption of some medicines, including certain antibiotics and thyroxine, and may affect the kidneys, liver or nervous system. (Source 4)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: people taking colloidal silver.
• How long: page last updated April 2023.
• Result: poor absorption of certain antibiotics and thyroxine; some evidence of kidney, liver or nervous system problems.
• Funding: not applicable.

Colloidal silver can cause poor absorption of some drugs, such as certain antibiotics and thyroxine (used to treat thyroid deficiency).

The most common serious side effect of colloidal silver is argyria, a usually permanent blue-grey discolouration of the skin. (Source 4)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: people taking colloidal silver.
• How long: page last updated April 2023.
• Result: silver builds up in the body's tissues; the discolouration is usually permanent.
• Funding: not applicable.

causing a bluish-gray discoloration of the skin, which is usually permanent.

What the evidence does not support

A randomised crossover trial found colloidal silver nasal spray produced no improvement over saline in recalcitrant chronic rhinosinusitis. (Source 5)

• Randomized trial, Low certainty.
• Size: 22 patients enrolled, 20 completed the full protocol.
• Who: adults with recalcitrant chronic rhinosinusitis without polyposis.
• How long: six weeks per arm, crossover.
• Result: mean 6-week change in SNOT-22 was -2.8 for saline and 1.0 for colloidal silver (p = 0.373); mean 6-week change in Lund-Kennedy score was -1.4 and -1.1 respectively (p = 0.794)
• Funding: independent; no funding was received.

Limit of this finding: The paper contradicts itself about its own design. Its title calls it a randomized crossover control trial, while its abstract says "A prospective cohort study was conducted using a convenience sample of 20 randomized patients with crossover methodology". What the investigators actually did was randomise 20 people to an order and cross them over, so it is recorded here as a randomised trial. Read it as one very small crossover trial, not as a large randomised trial and not as an observational cohort: with 20 people completing, it cannot rule out a small benefit or a rare harm, only show that no meaningful improvement appeared.

Mean 6-week change in SNOT-22 scores were −2.8 and 1.0 for saline and CS, respectively (p = 0.373).

The authors of that trial concluded commercially available colloidal silver nasal spray produced no meaningful subjective or objective improvement. (Source 5)

• Randomized trial, Low certainty.
• Size: 20 completers.
• Who: adults with recalcitrant chronic rhinosinusitis without polyposis.
• How long: 12 weeks total, crossover.
• Result: no meaningful change on either the symptom score or the endoscopic score.
• Funding: independent; no funding was received.

Limit of this finding: The paper contradicts itself about its own design. Its title calls it a randomized crossover control trial, while its abstract says "A prospective cohort study was conducted using a convenience sample of 20 randomized patients with crossover methodology". What the investigators actually did was randomise 20 people to an order and cross them over, so it is recorded here as a randomised trial. Read it as one very small crossover trial, not as a large randomised trial and not as an observational cohort: with 20 people completing, it cannot rule out a small benefit or a rare harm, only show that no meaningful improvement appeared.

Commercially available CS nasal spray did not demonstrate any meaningful subjective or objective improvements in patients with recalcitrant CRSsP.

Before that trial, no human trials of colloidal silver in this condition had been published anywhere in the literature. (Source 5)

• Randomized trial, Low certainty.
• Size: not applicable.
• Who: not applicable.
• How long: literature as of 2017.
• Result: no published human trials despite widespread naturopathic use and in vitro anti-biofilm activity.
• Funding: independent.

Limit of this finding: The paper contradicts itself about its own design. Its title calls it a randomized crossover control trial, while its abstract says "A prospective cohort study was conducted using a convenience sample of 20 randomized patients with crossover methodology". What the investigators actually did was randomise 20 people to an order and cross them over, so it is recorded here as a randomised trial. Read it as one very small crossover trial, not as a large randomised trial and not as an observational cohort: with 20 people completing, it cannot rule out a small benefit or a rare harm, only show that no meaningful improvement appeared.

To date, no trials involving humans have been published in world literature.

Studies of colloidal silver nasal spray for chronic sinus infections did not show meaningful improvement. (Source 4)

• Official position, Certainty not rated.
• Size: a few studies.
• Who: people with chronic sinus infections.
• How long: page last updated April 2023.
• Result: no meaningful improvements demonstrated.
• Funding: not applicable.

A few studies have evaluated the effectiveness of colloidal silver nasal spray to treat chronic sinus infections, but they did not demonstrate meaningful improvements.

What official bodies say

The US Food and Drug Administration ruled in 1999 that over-the-counter colloidal silver products are not generally recognised as safe and effective and are misbranded. (Source 6)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: all over-the-counter drug products containing colloidal silver ingredients or silver salts.
• How long: final rule issued 17 August 1999.
• Result: all such OTC products declared not generally recognised as safe and effective and misbranded; the rule states separately, in section D, that such ingredients cannot be included in an OTC drug product and that non-compliant products will be subject to regulatory action.
• Funding: not applicable.

all over-the-counter (OTC) drug products containing colloidal silver ingredients or silver salts for internal or external use are not generally recognized as safe and effective and are misbranded

The FDA stated it was not aware of any substantial scientific evidence supporting the marketed disease uses of colloidal silver. (Source 6)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: not applicable.
• How long: 1999.
• Result: no substantial scientific evidence identified for the claimed disease conditions.
• Funding: not applicable.

FDA is not aware of any substantial scientific evidence that supports the use of OTC colloidal silver ingredients or silver salts for these disease conditions.

NCCIH states, as of April 2023, that silver has no known function in the body and is not an essential mineral. (Source 4)

• Official position, Certainty not rated.
• Size: not applicable.
• Who: not applicable.
• How long: page last updated April 2023.
• Result: no known functions or benefits by mouth; not an essential mineral.
• Funding: not applicable.

Silver has no known functions or benefits in the body when taken by mouth, and it is not an essential mineral.

Where the research disagrees

Whether colloidal silver has any legitimate therapeutic use

• US Food and Drug Administration, 1999 final rule, position, following a rulemaking review of submitted data: FDA is not aware of any substantial scientific evidence that supports the use of OTC colloidal silver ingredients or silver salts for these disease conditions. (Source 6)
• Researchers citing laboratory antibacterial and antiviral activity of silver, in vitro and product-characterisation work, not human outcome trials: Colloidal silver has particularly benefited from this rush given its empirically and scientifically documented anti-bacterial and anti-viral actions. (Source 1)

How much

• Reference intake: No reference intake exists and none is possible: silver is not an essential mineral and has no known function or benefit in the body when taken by mouth. (Source 4)
• Upper limit: No upper limit has been set for supplemental colloidal silver. The FDA instead ruled in 1999 that over-the-counter products containing colloidal silver ingredients or silver salts are not generally recognised as safe and effective and are misbranded, so no safe intake is established. (Source 6)
• Studied: The only randomised human trial we found used a commercially available colloidal silver nasal spray, sprayed twice daily for six weeks, compared with saline. (Source 5)
• Studied: In a case report, a 16-year-old took colloidal silver by mouth for over a year before developing argyria. (Source 2)

A common belief, and what the research shows

The belief: Colloidal silver is a natural antibiotic that strengthens immunity and fights infection when you drink it.

What the research shows: Silver's germ-killing activity in a dish has never translated into demonstrated benefit in people. The only randomised human trial of colloidal silver found that 'Commercially available CS nasal spray did not demonstrate any meaningful subjective or objective improvements in patients with recalcitrant CRSsP.' NCCIH states that 'Silver has no known functions or benefits in the body when taken by mouth, and it is not an essential mineral.' What does happen is silver accumulation: NCCIH describes it 'causing a bluish-gray discoloration of the skin, which is usually permanent.'

Questions and answers

What is it?

Colloidal silver is a liquid containing tiny silver particles, sold online as a dietary supplement. Laboratory testing of popular commercial products found that most of them actually contain dissolved ionic silver rather than true silver nanoparticles, even when labelled as colloidal silver. Silver is not a nutrient. (Source 4)

What does it do in the body?

In the body, swallowed silver does nothing useful that has been demonstrated. It has no known biological function and is not an essential mineral. What it does do is accumulate in tissues, particularly the skin, where deposits produce a blue-grey colour that sunlight makes worse. (Source 4)

Is it good or bad for you?

For swallowing, the evidence points one way: no demonstrated benefit and a real risk of permanent discolouration. The FDA ruled in 1999 that over-the-counter colloidal silver products are not generally recognised as safe and effective. Silver dressings used on wounds in hospital are a different, regulated product and not the same thing as a supplement you drink. (Source 6)

How do you get more of it?

Does not apply in the usual sense: there is no reason in the literature to increase silver intake, and no body has set an intake to aim for. Colloidal silver is obtained only by buying supplement products, which are promoted online despite the absence of supporting evidence. (Source 4)

If it is harmful, what reduces it?

Mostly you cannot. Once silver has deposited in the skin the discolouration is usually permanent, and the only step the literature describes is stopping the silver. Cosmetic laser treatment has been offered in case reports for the appearance, not to remove the silver burden. (Source 4)

Why might someone be low in it or missing it?

Does not apply. Because silver has no known function in the body and is not an essential mineral, there is no such thing as being low in it, and no illness, medicine or diet can cause a silver deficiency. (Source 4)

Which whole foods contain it or feed it?

No whole food is a meaningful or necessary source, because silver has no known role in the body. The literature we searched discusses colloidal silver only as a manufactured supplement liquid, in products bought online, not as a food constituent. (Source 1)

What happens if you do not have it?

Nothing. There is no deficiency state for silver, no symptom of going without it, and no condition for which not taking colloidal silver has been shown to matter. The consequences described in the literature all come from taking it, not from lacking it. (Source 4)

How can you test for it?

There is no routine consumer test for silver status, and no reason to test for a substance with no known function. When argyria is suspected, clinicians work from the skin appearance and the history of silver use, with blood counts, liver and kidney function and an eye examination to look for deposits elsewhere. Diagnosis in the published cases rested on skin biopsy and history rather than on a validated silver test. (Source 2)

We searched: Searched the NCCIH colloidal silver page (April 2023), the FDA 1999 final rule, the 2017 randomised crossover trial and a 2025 argyria case report; none describes a validated test for silver status in a person.

References

1. International Journal of Nanomedicine. Comparative Analysis of Commercial Colloidal Silver Products. 2020. PMID 33376330, DOI 10.2147/IJN.S287730. Read the source
2. The Medical Bulletin of Sisli Etfal Hospital. A Re-emerging Disease Linked to Complementary Medicine: Argyria - Case Report. 2025. Read the source
3. The Medical Bulletin of Sisli Etfal Hospital. A Re-emerging Disease Linked to Complementary Medicine: Argyria - Abstract. 2025. Read the source
4. National Center for Complementary and Integrative Health (NCCIH), NIH. Colloidal Silver: What You Need To Know. 2023. Read the source
5. Journal of Otolaryngology - Head & Neck Surgery. The effectiveness of topical colloidal silver in recalcitrant chronic rhinosinusitis: a randomized crossover control trial. 2017. PMID 29178954, DOI 10.1186/s40463-017-0241-z. Read the source
6. US Food and Drug Administration, Federal Register Vol. 64, No. 158 (17 August 1999), 44653-44658. Over-the-Counter Drug Products Containing Colloidal Silver Ingredients or Silver Salts; Final Rule - SUMMARY. 1999. PMID 10558603. Read the source