Is It Safe to Eat Pizza That Was Left Out Overnight? Doctors Weigh In

DGIX

February 13, 2025

The Risks of Eating Pizza Left Out Overnight

We’ve all been there: a late-night pizza order, a few slices left uneaten, and the next morning, the temptation to dig in without a second thought. But is it safe? According to food safety experts, leaving pizza at room temperature for an extended period can pose serious health risks.

Dr. Emily Carter, a board-certified infectious disease specialist, warns: “Bacteria like Staphylococcus aureus and Bacillus cereus can multiply rapidly on perishable foods, especially those containing cheese and meat, when left out at room temperature for more than two hours. Eating pizza that’s been sitting out overnight significantly increases the risk of food poisoning.”

How Long Can Pizza Sit Out?

According to the USDA, perishable foods, including pizza, should not be left out for more than two hours at room temperature. After this period, bacteria can grow to dangerous levels, increasing the likelihood of foodborne illness.

A food safety researcher, Dr. James Reynolds explains: “While reheating might kill some bacteria, it doesn’t eliminate toxins that may have already formed. Even microwaving the pizza left out overnight won’t make it safe to eat.”

Can You Get Sick from Eating Pizza Left Out Overnight?

The short answer: is yes. Consuming pizza that has been left out for too long can lead to food poisoning, with symptoms such as nausea, vomiting, diarrhea, and stomach cramps.

Is It Safe to Eat Pizza That Was Left Out Overnight?

What About Pizza Left Out for 5-6 Hours?

If your pizza has been left out for less than six hours, some might argue it’s still safe to eat. However, food safety experts strongly advise against it.

“Even if the pizza looks and smells fine, it may contain harmful bacteria that can’t be detected by sight or smell,” says Dr. Lisa Thompson, a microbiologist.

The Myth of Reheating Pizza to Kill Bacteria

Many believe that reheating pizza left out overnight in the microwave or oven makes it safe. Unfortunately, this is a dangerous misconception. While high heat can kill bacteria, it does not eliminate the toxins they produce, which can still cause illness.

Bottom Line: Should You Eat That Leftover Slice?

While it’s tempting to grab that day-old, unrefrigerated pizza, experts agree it’s not worth the risk. If your pizza has been left out for more than two hours, it’s best to throw it away and avoid a potential bout of food poisoning.

Sources:

USDA Food Safety and Inspection Service (FSIS)
Centers for Disease Control and Prevention (CDC)
Interviews with Dr. Emily Carter, Dr. James Reynolds, and Dr. Lisa Thompson

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