Ketchup can be frozen, but its consistency after it has thawed is watery and jelly-like. Ketchup has a long shelf life. An unopened bottle can last for two years when stored in a pantry.
An opened bottle of ketchup can last for a year when refrigerated or up to a month if not refrigerated. As a bottle of ketchup ages, the water separates from the tomato paste. A bad bottle of ketchup does not have a typical bright red color and instead has a maroon color.
Ketchup in prepared dishes does not last as long as bottled ketchup. The quickest expiring ingredient in the dish determines whether it is still good or needs to be tossed out.