So how long do you keep ketchup and mayonnaise in your refrigerator?
The Food Safety and Inspection Service says some condiments last longer than others after they're opened. Ketchup can keep for about six months, while mustard can last for a year. As for mayonnaise and salad dressing, they're no good after two months. And pickles should only be kept for two weeks after opening.
You can look up other foods at www.fmi.org.