I find no interactions, but plenty of WARNINGS. I think I'd stay far away from it myself.
Currently, there are no evidence-based medical uses for colloidal silver.[1] There are no clinical studies in humans demonstrating effectivness, and several reports of toxicity.[9] The U.S. National Center for Complementary and Alternative Medicine has issued an advisory indicating that the marketing claims made about colloidal silver are scientifically unsupported, and that the silver content of marketed supplements varies widely and can pose risks to the consumer.[2]
Toxicities and interactions
Main article: Argyria
Excessive intake of silver products may result in a condition known as argyria, one symptom of which is blue or gray discoloration of the skin.[10] The discoloration occurs when silver is deposited in the skin and then darkened by sunlight, just as silver particles in photographic film darken when exposed to sunlight. Localized argyria can occur as a result of topical use of silver-containing remedies, while generalized argyria results from the ingestion of colloidal silver.[11] Arygria is usually permanent, and there is no known effective treatment.[11] While argyria is usually benign and limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications. A death has been reported in the medical literature as a result of colloidal silver use; in that case, a 71-year-old man developed status epilepticus which the authors felt was due to silver toxicity.[11][12]
A number of case reports describe argyria after ingestion of colloidal silver marketed as an alternative-medicine treatment.[13] Colloidal silver may theoretically interact with some medications, including tetracycline and quinolone antibiotics and penicillamine, reducing the effectiveness of those medications.[9]
[edit] Government regulation
In August 1999, the U.S. Food and Drug Administration (FDA) banned colloidal silver sellers from claiming any therapeutic value for the product, noting that such products were being marketed for numerous diseases without evidence of effectiveness.[8] The FDA also banned over-the-counter sale of drug products containing colloidal silver due to the lack of safety or efficacy data. The product now has the status of a dietary supplement in the US; it can be promoted with general "structure-function" claims, but cannot be marketed as preventing or treating any illness.[8]
Following this ruling, the FDA has issued numerous warnings to Internet sites which have continued to promote colloidal silver as an antibiotic or for other medical purposes.[14][15]
In 2002, the Australian Therapeutic Goods Administration (TGA) ruled that colloidal silver-containing products were no longer exempt from therapeutic goods legislation and had to meet the requirements of other products covered by this law. The TGA found that "there are no current legitimate uses of colloidal silver and that the Surveillance Section of the TGA be requested to investigate the illegal availability of colloidal silver products because of concerns about their significant toxicity. The reasons for the recommendation were that:
There is little evidence to support therapeutic claims made for colloidal silver products; the risk to consumers of silver toxicity outweighs the value of trying an unsubstantiated treatment, and bacterial resistance to silver can occur; and efforts should be made to curb the illegal availability of colloidal silver products, which is a significant public health issue.[16]