If you, like me, often find yourself staring into your refrigerator searching for something to nosh on that requires zero elbow grease to prepare, you’ve likely asked yourself the age-old question: Is it still safe to eat those once-delicious leftovers? The meal’s already been made, portioned out, and perfectly seasoned, after all. However, if the cooking of said leftovers happened more than a couple of days prior, you’re smart to ask.

Indeed, while there’s nothing we regret more than food waste, it is extremely important to keep your health front and center when it comes to emptying out your fridge—either onto a plate, or into the trash. When certain disease-causing bacteria contaminate food as a result of spoilage, they can cause serious symptoms, including vomiting and abdominal pain, as well as flu-like symptoms like fever and headache.

Keeping your leftovers in an airtight container below 40°F will certainly extend their lifespan, but not for as long as you likely assume. Here, we spoke with a few experts to learn more about visible and invisible signs of spoilage, and how to handle your leftovers safely to ensure that you’re not putting yourself (or those you’re dining with) at risk.

How long are leftovers good for?

As a general rule of thumb, you want to eat leftovers within three to four days, notes Samantha Cassetty, MS, RDN. “Be sure to store your food properly, too. Leftovers should be refrigerated in an airtight container, and your refrigerator should be set no higher than 40°F.”

But before they even make it to the fridge, one of the most important parts of proper leftover handling is being mindful of how long they sit out at room temperature before getting stored away. “Refrigerate or freeze meat, poultry, eggs, seafood, and other perishables within two hours of cooking or purchasing,” advises Amanda Turney, a spokesperson with the FDA’s Food Safety and Inspection Service (FSIS). “But refrigerate within one hour if the temperature where the food has been sitting is above 90°F.” This applies to outdoor picnics and barbecues in particular.

Conducting a quick fridge temperature test with a thermometer is a smart idea to ensure your highly perishable foods (including leftovers, but also raw meat, dairy, fish, and produce) are being kept at a temperature that is cold enough to ward off potentially harmful bacterial growth. Also, avoid keeping any of the above in the door of your fridge, as this is the warmest place in the refrigerator. Leftovers should be stored on a top or middle shelf towards the back—just make sure they’re within sight so you don’t forget to eat them until it’s too late.

If you’re going to freeze your leftovers, you should be able to get a little more mileage out of your food products. “Leftovers can be kept frozen for three to four months,” says Turney. “Although safe indefinitely, frozen leftovers can lose moisture and flavor when stored for longer times in the freezer.”

The key signs of spoilage to monitor

When it comes to identifying spoiled food, there are a few telltale signs to look out for. “You might notice texture changes, like a mushy fruit or veggie, or you might notice something looks slimy,” says Cassetty. Mold is also a key indicator, and while you may be tempted to scrape off the small patches and eat the rest, keep in mind that mold often has threads that extend deep below the surface. This, of course, means scraping off the patch doesn’t mean you’ve gotten rid of the mold altogether.

“Sometimes, you’ll notice an off odor,” adds Cassetty. Souring and rotting smells are never good in food, and are certainly a reason to get rid of your leftovers. That said, as Cassetty points out, “Food can develop bacteria that can make you sick even if there are no differences in taste, appearance, or odor. That’s why it’s so important to handle and store food properly before any of this occurs.”

Foods that are at a higher risk of spoilage

“Pre-cut fruits and veggies, berries, and ready-to-eat salad greens are really perishable, so be careful with these foods,” Cassetty warns. “I’d also be cautious with ground meat and raw poultry. These items should be cooked or frozen within two days of purchase.”

Be sure to keep an eye on the FDA’s specific storage instructions, which include guidelines for both timing and temperature of various ingredients.

The safest way to reheat leftovers

As important as storing your leftovers is, bringing them back to life is also key to ensuring that you don’t make yourself sick.

If you’ve frozen your leftovers, getting them up to temperature is step one. “Safe ways to thaw leftovers include the refrigerator, cold water, and the microwave oven,” explains Turney. “Refrigerator thawing takes the longest but the leftovers stay safe the entire time, because they never go above 40°F. After thawing, the food should be used within three to four days or can be refrozen.”

As mentioned, you can also thaw your leftovers in cold water, but be sure to do so in leak-proof packaging like a plastic bag. “If the bag leaks, water can get into the food and bacteria from the air or surrounding environment could enter it,” Turney says. “Foods thawed by the cold water method should always be cooked before refreezing.”

And when you’re ready to actually reheat your leftovers, be sure that you get your food items warm enough to kill bacteria. “Continue to heat leftovers until they reach 165°F as measured with a food thermometer,” Turney adds. “Foods thawed in the microwave can be refrozen after heating it to this safe temperature.” If you’re reheating soups (hi, leftover soup ideas), gravies, or other liquids, bring them to a rolling boil on the stove to make sure that you’re killing all potential bacterial growth.

At the end of the day, however, it’s better to be safe than sorry when it comes to your leftovers. “It’s smarter to throw something out than risk getting ill,” says Cassetty. “If anything is suspect, don’t risk it! That being said, since food waste is a major contributor to climate change, try to get organized around your shopping list, manage leftovers, and freeze what you won’t eat within the safe window.”

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