My wife says after opening coca cola, it can't be stored for more than a few days becus when the gas in the drink runs out, there are toxins. true?

Coca Cola: Alleged toxic acidity levels are baseless. Lawsuits based on these notions have been dismissed by several American courts. Although numerous court cases have been filed against The Coca-Cola Company since the 1920s, alleging that the acidity of the drink is dangerous, no evidence corroborating this claim has been found. Scientific evidence indicates Coca-Cola's acidity has no harm associated.