What is Silver?
Silver is a relatively safe metal that has some antimicrobial benefits. Historically, silver has been used as an antimicrobial in folk medicine. Presently, silver solution is still used as an antimicrobial and silver is often used as part of wound dressings and medical devices to reduce risks of infections [1, 2].
Since the advent of antibiotics that are less expensive than silver, silver use for antimicrobial purposes has decreased. However, with the rising antibiotic resistance, colloidal silver is considered an alternative that may be able to overcome this major public health issue .
What Is Colloidal Silver?
Colloidal silver is a suspension of very small silver crystals that are between 10 and 100 nm in size. It can be prepared either by mechanically grinding metallic silver into very small particles or using an electrochemical reaction to convert silver salts into small silver crystals .
It is important to distinguish between colloidal silver and silver salt solutions (Ag+ in silver chloride, silver nitrate, and silver oxide) because they are different things. Metallic silver and colloidal silver are much less toxic to both humans and germs than silver salts. Pure colloidal silver should not react with air and form silver oxide precipitates.
However, homemade or low-quality colloidal silver products may have a substantial amount of silver salt remaining in the solution. In addition, a small fraction of silver nanoparticles can be chemically converted back into a silver salt by substances in the body or the environment. It is possible that the small number of silver ions may be responsible for the antimicrobial effects of colloidal silver. However, the silver salt is responsible for many of the colloidal silver’s side effects.
Health Benefits of Colloidal Silver
1) Colloidal Silver Is Antimicrobial
Historically, people have used silver for its antibacterial, antiviral, and antifungal properties. However, the FDA does not recognize colloidal silver as a safe antimicrobial agent .
How Does Colloidal Silver Work?
Colloidal silver disrupts the cell membranes of fungi and stops reproduction .
In a case report of a 12-year-old boy with a cystic fibrosis lung disorder, colloidal silver supplement efficiently treated Pseudomonas aeruginosa. P. aeruginosa is a multi-drug resistant bacteria that causes pneumonia .
In various cell studies, colloidal silver and silver nanoparticles prevented the growth of:
- Bacillus cereus 
- Mycobacterium smegmatis 
- Salmonella typhimurium 
- Streptococcus pyogenes 
- Staphylococcus aureus bacteria [14, 6]
- Hepatitis B virus 
- Herpes simplex virus 
- Candida albicans and Candida glabrata fungi 
- Microsporum Canis 
- Trichophyton mentagrophytes 
- Microsporum gypseum fungi 
Colloidal silver has no effect against these viruses:
Most studies that evaluate the antimicrobial effects of colloidal silver are cell-based studies. Others are studies that test colloidal silver for topical or external use. While it is truly a potent anti-microbial agent, it is possible that, when taken internally, colloidal silver may not reach sufficient concentration to have the same effectiveness as in these cell-based studies.
2) Colloidal Silver Helps Heal Wounds
Silver nanoparticles have antimicrobial and anti-inflammatory properties that make it effective in treating cuts, scrapes, burns, and other wounds. It also works in treating wounds that are infected by drug-resistant strains [18, 19].
In one case study, topical application of colloidal silver ointment helped heal a patient’s skin wounds. The ointment’s antimicrobial activity worked with antibiotics to heal the wound faster and prevent skin infection .
Colloidal silver also stopped bacterial growth in human cells .
3) Colloidal Silver May Help with the Common Cold
In a study of 100 children affected by the common cold, a combination of colloidal silver and carboxymethyl beta-glucan was more effective than applying salt water (saline) solution. Ninety percent of the children that used the colloidal silver solution had less inflammation in their ear and airways, while only 66% that used salt water solution had reduced inflammation .
4) Colloidal Silver May Help Treat Sinus Infections
In a sheep model of rhinosinusitis (sinus infection), topical colloidal silver treatment in their sinuses reduced bacterial growth. Colloidal silver also killed the bacteria and suppressed inflammation, which helped treat the infection .
However, in a 12-week study (randomized cohort) of 20 patients, 6 weeks of colloidal silver nasal spray and 6 weeks of salt water solution treatment did not help treat long-term rhinosinusitis. Even though it did not have any side effects, it was not powerful enough to treat sinus infections .
5) Colloidal Silver Kills Cancer Cells
In human breast cancer cells, colloidal silver may prevent cancer progression. Colloidal silver triggered apoptosis (programmed cell death) of cancer cells by activating the caspase pathway and inhibited cancer progression .
Colloidal silver also decreased lactate dehydrogenase levels in human breast cancer cells. It is an enzyme that helps with energy production in cancer cells .
Because these are cell-based studies, clinical studies would be necessary to confirm the safety and effectiveness of colloidal silver as a cancer treatment.
6) Colloidal Silver May Reduce Inflammation
Possible Other Benefits of Colloidal Silver
Silver nanoparticles have other health benefits. However, no experiments using colloidal silver have been performed on humans regarding these health effects.
Side Effects of Colloidal Silver
Colloidal silver may interact with and damage DNA .
Prolonged and Extreme Use of Colloidal Silver May Cause Argyria
Colloidal silver generally has no side effects. However, prolonged use of colloidal silver may lead to a condition known as argyria, from the small number of silver ions that may arise from the silver nanoparticles. The silver ions accumulate in the tissues, causing the skin to turn blue-gray. Argyria is not a life-threatening condition, but it is irreversible .
In a case report, a diabetic patient who used a commercial colloidal silver product (Silver Zone) for 2 years developed an unusual darkening of the skin in the nail beds .
A 70-year-old chronic sinusitis patient who used colloidal silver (10% silver vetillinate) as a nasal decongestant experienced an unusual gray pigmentation in her nail beds and skin .
Colloidal Silver May Be Toxic to the Gut
Ingesting colloidal silver can be harmful to the stomach and intestines. In multiple rat studies, silver nanoparticles disturbed their gut flora. Damage to the gut flora can cause problems with the gut immune response [36, 37].
Additionally, colloidal silver ingestion also damaged cut cells .
Limitations and Caveats
Few human studies are available regarding colloidal silver’s effects on health. More clinical studies are needed to determine its long-term effects on humans.
It is therefore not advised to take colloidal silver on a regular basis or in very high doses.
Silver also interacts with drugs containing the inactive ingredient sodium thioglycollate. The thiol group decreases the antimicrobial potency of colloidal silver .
Since there are only a few human studies available, there is no recommended dosage of colloidal silver supplements. One clinical study used 10 to 32 ppm of silver particle solution without causing any toxicity .
One user stated that her son had a productive chronic cough and difficulties in breathing, but when he took 20 mL of colloidal silver, his situation improved tremendously.
Another user who had a tooth infection revealed that the moment she used colloidal silver as a mouthwash, her tooth infection disappeared.
A patient who had a sore throat also claimed that she got relieved when she took 20 ppm of colloidal silver orally.
A patient stated that he used colloidal silver as a therapy for allergy for 3 years until he developed an abnormal darkening of the skin in the nail beds. He visited the doctor and was advised to cease using the colloidal silver solution.