In animals and humans, silver accumulates in the body.[9]:121 Chronic intake of silver products can result in an accumulation of silver or silver sulfide particles in the skin. These particles in the skin darken with exposure to sunlight, resulting in a blue or gray discoloration of the skin known as argyria.[7] Localized argyria can occur as a result of topical use of silver-containing solutions, while generalized argyria results from the ingestion of such substances.[36]
Argyria is generally irreversible, with the only practical method of minimizing its cosmetic disfigurement being to avoid the sun.[37] Preliminary reports of treatment with laser therapy have been reported. These laser treatments are painful and general anesthesia is required.[38][39] A similar laser treatment has been used to clear silver particles from the eye, a condition related to argyria called argyrosis.[40] The Agency for Toxic Substances and Disease Registry (ATSDR) describes argyria as a "cosmetic problem".[41]
While argyria is usually limited to skin discoloration, there are isolated reports of more serious neurologic, renal, or hepatic complications caused by ingesting colloidal silver.[36][42]
Colloidal silver may interact with some prescription medications, reducing the absorption of some antibiotics and thyroxine among others.[43]
