What Happens If You Don't Refrigerate Your Packed Lunch? (2024)

The situation
If you're a devoted lunch packer, then you've no doubt found yourself in the situation of having brought your midday meal to work, stashing it in your desk drawer, and crossing your fingers that it'll be fine without refrigeration for a few hours (particularly if your office fridge is too packed to store anything in it anyway).

What you're worried about
While you can't even recall how many times you left your lunch in your locker as a high school student without a problem, you still have a nagging feeling that it's only a matter of time before your room-temperature turkey sandwich or yogurt makes you sick. (Snack AND lose weight with this box of Prevention-approved treats from Bestowed.)

The real risk
"The big issue is that bacteria such as E. coli, salmonella, and listeria can begin growing on food in this amount of time and get to a level where they can actually cause people to become ill if they ingest it," says Samuel Crowe, an epidemiologist at the Centers for Disease Control and Prevention. "Common symptoms include nausea, vomiting, stomach cramps, and diarrhea, which can present within 6 to 12 hours, or sometimes even a couple days after the ingestion of the food."

The CDC estimates that about 48 million people get sick from a foodborne illness each year, out of which 3,000 die—so even if you've left your lunch out before and not gotten sick, it's simply not worth the risk, particularly if you have a health condition that compromises your immune system in any way, such as diabetes, autoimmune diseases, or cancer; or if you're over age 65.

MORE: 26 Food Poisoning Treatment Methods

To stay safe, sandwiches, salads, and other meals with perishable ingredients shouldn't be left at room temperature for more than 2 hours—max. Leftovers should also go back in the refrigerator within 2 hours. Even if your lunch just contains one ingredient that's questionable—like mayonnaise—the whole thing should go in the fridge, Crowe says.

And if, for some reason, your meal is exposed to heat (like if you walk to work), then the growth of bacteria and germs becomes a concern even sooner: Food shouldn't be left unrefrigerated for more than an hour if it's being exposed to weather that's at or above 90 degrees.

You may, however, be able to get away without refrigeration if you prepare your lunch the night before and toss it in the fridge (so everything's cold by morning), and then pack it in a freezable insulated lunch bagin the morning, along with an additional cold source like an ice pack, says Crowe.

One lunch you may be able to get away with not tossing in the fridge, however, is a peanut butter and jelly sandwich, since none of those ingredients are perishable, says Crowe. But other than that, there aren't many options—at least healthy ones—that fit the bill.

MORE: 4 Signs You Have Food Poisoning

Bottom line:
It may sound ridiculous, but nearly anything you pack for lunch and leave out for more than a couple of hours (without taking proper steps to keep it cool) should be tossed to save you from potential food poisoning. Unless, of course, you survive solely on PB&Js, which we can't say we recommend.

At least now you have a good reason to invest in a trendy new lunch bag!