- Argyria is a blue-gray discoloration of the skin caused by ingestion of silver. Colloidal silver is available in a variety of OTC tonics and has been used for centuries as an antimicrobial. Unfortunately, chronic use of silver can cause a permanent Tin Man appearance (and The Food and Drug Administration (FDA) in 1999 issued a final rule establishing that 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.