Argyria (ISV from Greek: αργύρος argyros silver + -ia) is a disease caused by the ingestion of elemental silver, silver dust or silver compounds. The most dramatic effect of argyria is that the skin is colored blue or bluish-grey. Argyria may be found as generalized argyria or local argyria. Argyrosis is the corresponding condition related to the eye. The condition is believed to be permanent. Most recent cases are due to the over consumption of home made colloidal silver as an alternative medicine.

Since at least the early part of the 20th century, doctors have known that silver or silver compounds can cause some areas of the skin and other body tissues to turn gray or blue-gray. Argyria occurs in people who eat or breathe in silver over a long period (several months to many years). A single exposure to a silver compound may also cause silver to be deposited in the skin and in other parts of the body; however, this is not known to be harmful. It is likely that many exposures to silver are necessary to develop argyria. Once argyria develops, it is believed to be permanent. However, the condition is thought to be only a "cosmetic problem". Most doctors and scientists believe that the discoloration of the skin seen in argyria is the most serious health effect of silver (in small doses).

Reports of cases of argyria suggest that gram amounts (from 2 to 4 grams) of silver or a silver compound taken in medication in small doses over several months may cause argyria in some humans. People who work in factories that manufacture silver can also breathe in silver or its compounds. In the past, some of these workers have become argyric. However, the level of silver in the air and the length of exposure that caused argyria in these workers is not known. It is also not known what level of silver causes breathing problems, lung and throat irritation, or stomach pain in people. Studies in rats show that drinking water containing very large amounts of silver (9.8 grams of silver per U.S. gallon water or 2.6 grams per liter) is likely to be life-threatening.

There is very little information about health effects following skin contact with silver compounds. Argyria that covers the entire body is not seen following skin contact with silver compounds, although the skin may change color where it touches the silver. However, many people who have used skin creams containing silver compounds such as silver nitrate and silver sulfadiazine have not reported health problems from the silver in the medicine. In one animal study, a strong solution of silver nitrate (81 milligrams silver nitrate per liter of water) applied to the skin of guinea pigs for 28 days did not cause the animals to die; however, it did cause the guinea pigs to stop gaining weight normally. It is not known if this would happen to people if they were exposed the same way.