What happens when you eat copper pennies?

Pennies minted after 1982 are made out of 99% zinc so that if the penny is worn down enough so that the zinc shows thru the copper coating, then the penny is a piece of zinc that can react with the hydrochloric acid in the stomach to produce hydrogen gas and be poisonous to the internal organs. read more

The amount of copper oxide on the pennies will vary depending on how they have been stored, how old they are and how much copper is in the pennies. Pennies minted between 1962 and 1982 work well for this experiment, as they contain 95 percent copper and have been in circulation long enough to build up a coating of copper oxide. read more

They found that after a week, the silver coins and copper pennies were unaffected, but the newer zinc pennies with copper coatings were eaten away by the acid, losing 5 to 8 percent of their weight. Zinc reacts with stomach juices to form hydrogen gas and zinc chloride, which can cause stomach ulcers. read more