Curds like muenster, gorgonzola, and havarti might last a little longer: two weeks past their sell-by dates. But semi-hard cheeses like Cheddar and Swiss can last up to two months past their suggested expirations, and hard cheeses like Parmesan for up to four.
Can old cheese make you sick?
Best-case scenario: Nothing. It could taste bad or you might get an upset stomach. In-between scenario: You could have a moderate allergic reaction, contract a foodborne illness, or have respiratory issues. Worst-case scenario: You could be hospitalized, put on dialysis, or even die.
Should Swiss cheese be refrigerated?
Swiss cheese doesn’t actually have to be refrigerated. Refrigeration only keeps the cheese from getting moldy as fast. It may “sweat” or get hard around the edges if you leave it out for too long, but it won’t hurt you to eat.