Reader Questions

Colloidal silver has been called a natural antibiotic. Is there any truth to this, and are there any risks to consuming silver?

Response: The promotion and use of silver products is a revival of a 19th century fad in which silver compounds were touted as panaceas. Although the most popular claim for currently marketed silver products is that they are "natural" antibiotics capable of preventing and treating infections, manufacturers of these supplements have claimed that silver is an "essential" mineral and that silver compounds are helpful in more than 650 different diseases.1

Silver compounds do have antibiotic effects and have been used for this purpose for centuries. Prior to World War II, silver compounds were quite popular to treat infections ranging from colds to gonorrhea. Now available in oral solutions, aerosols, vaginal douches, and injectables, silver compounds have been advertised as efficacious for preventing cancer, AIDS, and diabetes, and for treating systemic fungal infections, tuberculosis, and malaria.1

Although small, harmless amounts of silver are found naturally in mushrooms, milk, and bran, silver is not an essential mineral and can accumulate in the body.1 Argyria refers to the bluish skin discoloration caused by silver deposits in the dermis. Although this discoloration is harmless, it is permanent, and treatment with chelating agents is usually ineffective.2 Long-term use has resulted in silver deposits in visceral organs;1 in rare cases neurological deficits have been observed.3 The minimal oral dosage necessary to cause systemic argyria is 25-30 g over six months.2

Silver acetate is used in some smoking deterrent lozenges and chewing gums, and several cases of argyria have been reported in heavy users of these preparations. Decorated desserts may also contain silver; the metallic sugar balls used to decorate cakes are coated with real silver, and bits of silver foil are sometimes used to decorate desserts, especially in India. About 10 cases of argyria were reported in Japan due to breath fresheners (Jintan brand) that contained silver.2 A recent case of argyria was reported in a 79-year-old man who, in order to stop smoking, consumed silver sugar cake decorations for 15 years.2 Over three years, he developed blue lunulae and a gray-brown discoloration over his skin, particularly prominent in the sun-exposed parts of his face, neck, and hands. In one case, a schizophrenic patient who had consumed silver anti-smoking pills for 40 years developed seizures; an extremely high serum concentration of silver was detected.4

The marketing of silver as a "natural antibiotic" is misleading. Short-term use for a cold would probably cause no harm (although there is no evidence that it is effective). The possibility that patients may think that silver is an adequate treatment for bacterial or systemic fungal infections could have serious adverse consequences. And if consumers ingest silver preparations regularly in the hopes of averting infections, more cases of argyria can be expected in the future. Although the most common manifestation of argyria, discoloration of the skin, is harmless, the gray coloration is permanent and cosmetically unappealing.

Adriane Fugh-Berman, MD

References

1. Fung MC, et al. Colloidal silver proteins marketed as health supplements. JAMA 1995;274:1196-1197.

2. Hanada K, et al. Silver in sugar particles and systemic argyria. Lancet 1998;351:960.

3. Westhoven M, Schafer H. Generalized argyrosis in man: Neurological, ultrastructural and x-ray micro- analytical findings. Arch Otorhinolaryngol 1986; 243:260-264.

4. Ohbo Y, et al. Argyria and convulsive seizures caused by ingestion of silver in a patient with schizophrenia. Psych Clin Neurosci 1996;50:89-90.

28. Excess silver consumption can cause:

a. gray discoloration of the skin.

b. blue lunulae.

c. neurological deficits.

d. All of the above.

29. Treatment of argyria by chelation is generally:

a. ineffective.

b. effective.