Does Pizza Go Bad If Left Out Overnight?

Pizza is one of those universal comfort foods that’s versatile enough for basically anyone to enjoy. Unfortunately, it’s also great for busy parties and ordering a late night snack. All together, this means it can be easy to accidentally leave your pizza out overnight. And the ingredients can range from simple cheese to elaborate poultry. We’ve thoroughly researched if pizza will go bad when you’ve left it out overnight.

It is always important to keep your pizza refrigerated instead of leaving it out overnight. The leftover pizza must be put in your fridge within two hours. This includes ordinary cheese pizza with no pile of extra toppings. That’s because some bacteria that grows on food is able to build up very quickly at room temperature. This bacteria has a good chance of making you ill.

Pizza is a very tasty treat, so you’ll probably try your best to save any leftovers. But there are important rules to follow if you want to feel safe about eating it. Keep reading to learn more about why you can’t eat unrefrigerated pizza, how to tell when it’s bad, and how to deal with bacteria.

A woman taking a big slice of pepperoni, Does Pizza Go Bad If Left Out Overnight?

Can you eat pizza that's been left out all night?

It is no secret that reheated pizza doesn’t quite taste the same as the fresh serving. So you might feel pretty tempted to just leave the leftovers as is. Or, you may not be all that worried about taking a risk.

But no matter what your motives are, the science of leftovers isn’t going to change. Unfortunately, you should never eat pizza that’s been left out for an entire night. In fact, you aren’t even supposed to eat pizza that’s been sitting out for a couple of hours. Make sure that you refrigerate and reheat your pizza within the proper time frames. There are products that can help restore enough of the flavor you want.

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How long does it take pizza to spoil?

According to FoodSafety, a “.gov” website, you should discard a pizza that has been held above forty degrees for more than two hours. This applies to pizzas with any kind of topping.

The rule for two hours is reinforced by the United States Department of Agriculture. The USDA was also referenced by safety specialists Canitgobad, specifically regarding pizza. This source also mentions that the USDA advises you to eat refrigerated pizza within four days.

An up close photo of a pepperoni pizza with chili sauce on the background

Will bacteria grow on pizza that’s been left out all night?

You should completely disregard exceptions when you, family, or friends have successfully eaten unrefrigerated food without becoming ill.

If you leave pizza at room temperature past the recommended two hours, then you will risk eating your pizza with a brand new topping of dangerous bacteria. This bacteria is classified as “food-borne,” and there are multiple kinds of threats that will likely make you sick.

It’s important to understand what bacteria you could be subjected to, in order to begin storing and eating your pizza safely.


For example, listeria is just one type of bacteria that can grow quickly on food. It’s been known to contaminate sausage and soft cheeses like feta cheese. Both of these ingredients are familiar toppings for specialty pizzas.

The Food and Drug Administration warns that listeria can even grow in the refrigerator, and result in very serious symptoms. Aside from the fever or vomiting, the FDA advises that listeria can be lethal for people who are very young or old.

Staphylococcus aureus

Staph bacteria is one of the more common food-borne threats. That’s because staph bacteria can be found basically everywhere, including on your skin. If you don’t wash up before you eat, then you’re definitely spreading staph bacteria all over your food.

The Centers for Disease Control state that staph bacteria will probably give you a full day of vomiting and diarrhea. Even worse, the CDC warns that you wouldn’t be able to use conventional means to detect if your food has developed staph bacteria. The food may not look any different than before, and staph bacteria may not produce a noticeable odor.

Clostridium perfringens

This bacteria is the most common, traditional vehicle for food poisoning as you know it. It’s known to develop on meat and poultry, which are common toppings for pizza. Chances are, you’ve added some kind of meat to your pizza such as pepperoni, chicken, or sausage. If C. perfringens grows on your pizza, then you could end up with cramps and diarrhea for a full day.

Will reheating pizza kill bacteria?

Delicious pizza with melted cheese

Different bacteria will react differently when you reheat pizza. For example, take the resilient staph bacteria into account. Experts like StopFoodborneIllness warn that staph bacteria cannot be destroyed by reheating.

That’s because the actual toxins from staph bacteria will survive and remain a threat. But the same source also adds that you can reheat fresh food as soon as it arrives. This would actually extend your time frame to two hours again. Nonetheless, the leftovers still have to be refrigerated before the new set of two hours.

For listeria, the reliable “.org” website MotherToBaby suggests that you can reheat refrigerated leftovers to 165 degrees Fahrenheit or more to safely eat again. As long as the food was refrigerated within the two-hour window, you can reheat your food at the same temperature to avoid C. perfringens too.

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Just bear in mind that experts like Kaiser Permanente have advised that reheating food may not always rescue leftovers that are already contaminated.

Although they are speaking broadly, the suggestion remains crucial for all health and safety. The general consensus from all reliable sources is to throw anything out, if you are not certain the food was stored properly. If you're eating a full Italian meal, you can read this post to learn what temperature you should use when you bake and reheat lasagna.

How can you tell if pizza is bad?

To begin with, it’s never a good idea to taste food in order to determine its safety. Most health specialists will warn you that tasting bad pizza is likely going to make you sick. Instead, you should try to recognize other signs of spoiled pizza.

For example, mold spores are airborne and will absolutely take up residence in your pizza. This microscopic fungus will create noticeable spots on your food. Mold is likely to grow on cheese, which can become sour and may also develop spots.

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Another great way to tell if your pizza has spoiled is by reviewing the crust. Pizza crust is just dough, which can be altered in many different ways over time. To begin with, it’s surely going to dry out. If your pizza crust has been out for too long, then it will become flaky, grey, and smelly. This crust is made from flour. If you're making your own crust, you can read this post to learn if flour lasts longer in the freezer.

If you put mushrooms on your pizza, they may begin to warp or look strange. Mushrooms can become wrinkled and even slimy when they begin to spoil.

How can you tell if frozen pizza has gone bad?

But that’s all about fresh pizza. Don’t forget to check the frozen pizza you’ve stored and forgotten all about since last summer. If you want to whip out a long lost pizza, then the first thing you should check for is discoloration. That happens to just about any food when it’s subjected to freezer burn. If your pizza already has freezer burn, you should really double-check the due date on the packaging.


It’s always tempting to rescue what you can from a leftover pizza. It can be easy to forget pizza sitting out, especially when you’ve intentionally left the food out for a group to share. Anything from a late game or a children’s birthday party can have you wondering about overnight pizza. Now you know the risks of eating leftover pizza, and how to properly avoid any kind of bacteria. So, the only thing you have to worry about is ordering the next one!

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