It’s a common situation. You order a delicious pizza for dinner but can’t finish it all. Rather than put it away properly in the refrigerator, you leave it out on the counter overnight. When morning comes, you consider eating the leftovers for breakfast but wonder – is it still safe to eat pizza that’s been left out overnight?
Quick Answer
The quick answer is no, it’s not recommended to eat pizza that’s been left out at room temperature overnight. After two hours at room temperature, bacteria can multiply quickly on perishable foods like pizza and cause food poisoning when eaten. The safer option is to discard the pizza.
How Long Can Pizza Sit Out?
Freshly baked pizza is safe to eat at room temperature for up to two hours. After this point, the warmth and moisture of the pizza creates an environment where bacteria can thrive and multiply rapidly. Leaving pizza out for longer than two hours is not recommended.
According to food safety guidelines, refrigerated pizza should be discarded if left out between 40°F and 140°F for more than two hours. This is considered the “danger zone” for bacterial growth.
What Happens When Pizza is Left Out Overnight
Overnight, a pizza left out on the counter will usually be sitting at room temperature for 8 or more hours. This is well beyond the recommended 2 hour window.
During this extended time, bacteria such as Staphylococcus aureus, Bacillus cereus, and Salmonella can grow and produce toxins that cause food poisoning. The longer the pizza sits out, the greater the bacterial contamination.
In addition to bacterial growth, chemical changes will occur in the pizza ingredients. Fats can turn rancid, cheese can separate, and crust and toppings will dry out. So the pizza will not only become unsafe, but the textures and flavors will deteriorate.
Is Reheating Leftover Pizza Enough?
Unfortunately, reheating pizza that’s sat out all night is not enough to make it safe to eat. While heating pizza to 165°F will kill most bacteria, it does not neutralize the dangerous toxins already produced by the bacteria.
These toxins can cause symptoms like nausea, vomiting, diarrhea, abdominal cramps, and fever even after the pizza has been reheated. The damage has already been done by the bacterial overgrowth during the time the pizza was left out.
What About Microwaving Pizza in the Morning?
Microwaving leftover pizza in the morning that was improperly stored overnight does not make it safe to eat. The microwave may heat up the pizza, but it does not reach high enough temperatures to kill all the bacteria and toxins.
Studies show that microwaving pizza for 60 seconds can only increase the temperature to around 130°F-140°F. This does not reach the 165°F needed to destroy contaminants. Microwaving also creates hot spots rather than evenly heating.
For these reasons, microwaving does not guarantee the pizza is safe after sitting out all night. It’s still best to discard pizza left out more than 2 hours.
What Happens If You Eat Pizza Left Out Overnight?
Eating pizza that’s been left out too long can cause food poisoning with symptoms like:
- Nausea
- Vomiting
- Abdominal cramps
- Diarrhea
- Fever
- Headache
- Muscle aches
Symptoms can begin anywhere from 30 minutes to 48 hours after eating contaminated pizza. The duration of illness usually lasts 1-3 days.
In severe cases, food poisoning from pizza left out overnight can even cause dehydration and hospitalization. Vulnerable groups like pregnant women, children, older adults, and those with weakened immune systems are at higher risk for complications.
Common Causes
The most common causes of food poisoning from eating pizza left out too long include:
- Staphylococcus aureus – Causes stomach cramps, nausea, and diarrhea. It’s found in moist, high-protein foods like cheese and meat.
- Bacillus cereus – Also causes vomiting and diarrhea. It’s found in starchy foods like pasta, rice, and bread.
- Salmonella – Leads to diarrhea, fever, and abdominal cramps. It’s found in eggs, meat, poultry, and dairy.
- E. coli – Results in severe stomach cramps and bloody diarrhea. It contaminates foods via improper handling and cooking.
- Clostridium perfringens – Causes watery diarrhea and abdominal cramps. It grows in cooked meat and poultry.
Who is at Risk?
Anyone who eats pizza that’s sat out too long is at risk of food poisoning. However, some groups are more susceptible to getting sick from foodborne bacteria:
- Pregnant women – Hormonal changes make them more vulnerable.
- Young children – Their immune systems aren’t fully developed.
- Older adults – They have weaker immune systems.
- Those with chronic illnesses – Diseases like diabetes, kidney disease, and HIV affect immunity.
- Those taking medicines like steroids or chemotherapy – The drugs impair the immune system.
Those with increased susceptibility should be especially careful about eating leftovers like pizza that have been left out too long. The consequences could be more severe.
How to Store Pizza Safely
To enjoy leftover pizza safely, it needs to be stored properly. Follow these guidelines:
Freshly Baked Pizza
- Eat hot pizza within 2 hours of baking.
- Leftover pizza should be refrigerated within 2 hours.
- Store pizza in shallow airtight containers or rewrap in aluminum foil to prevent drying out.
- Refrigerate for 3 to 4 days maximum.
- Can be frozen for 1 to 2 months.
Take-Out Pizza
- Refrigerate take-out or delivery pizza immediately if not eating right away.
- Use within 3 to 4 days after refrigerating.
- Avoid letting the pizza sit out more than 2 hours before refrigerating.
- Reheat refrigerated slices thoroughly before eating.
Reheating Tips
- Reheat refrigerated pizza to 165°F.
- Use oven or toaster oven to reheat thoroughly.
- Microwave only if using microwave-safe container and rotating for even heating.
- Bring pizza sauce to a boil when reheating.
- Discard slices if they have an off smell, flavor, or appearance.
Proper storage and handling prevents bacterial growth and makes leftover pizza safe to enjoy.
Can You Eat Pizza Left Out Overnight if You Microwave It?
Microwaving does not make pizza safe to eat after it has been left out overnight. The microwave is not able to heat the pizza evenly to 165°F needed to destroy bacteria and toxins.
Studies have found microwaving pizza for 60 seconds only heats it to about 130-140°F. Parts may even remain cold while other parts get scalding hot.
This means bacteria and toxins can survive microwaving. Consuming pizza left out overnight can still cause food poisoning, even if microwaved briefly before eating.
What Temperature Kills Bacteria on Pizza?
Bacteria are killed and made safe on pizza and other leftovers when they are heated to an internal temperature of 165°F or above. This temperature is high enough to destroy most dangerous pathogens.
Some of the bacteria that can grow on pizza left out too long include:
| Bacteria | Minimum Temperature to Kill |
|---|---|
| E. coli | 155°F |
| Salmonella | 160°F |
| Listeria monocytogenes | 165°F |
| Staphylococcus aureus | 165°F |
Heating pizza to 165°F via oven, stove, or skillet will destroy these and other harmful bacteria. Microwaving often doesn’t reach high enough temperatures throughout.
Can You Get Food Poisoning from Pizza Left Out Overnight?
Yes, you can absolutely get food poisoning from eating pizza that’s been left out of refrigeration overnight. The combination of time and temperature creates an environment where dangerous bacteria multiply rapidly.
When the pizza has sat between 40°F and 140°F for more than 2 hours, bacteria produce toxins that cause illness. Even if you reheat the pizza, these toxins are heat-stable and can still make you sick.
Symptoms like diarrhea, vomiting, fever, and stomach cramps start within hours or days of eating contaminated pizza that sat out too long. In severe cases, hospitalization may be required for dehydration or infection.
The easiest way to prevent food poisoning is to discard leftover pizza if it has been left out more than 2 hours. Don’t take risks by trying to reheat and eat pizza left out overnight.
Can Left Out Pizza Make You Sick?
Yes, pizza that has been left out too long can definitely make you sick. When pizza is left at room temperature for more than 2 hours, it enters the danger zone of 40°F to 140°F. In this temperature range, bacteria grow rapidly and produce toxic byproducts.
Even if you reheat the pizza before eating, these toxins can still cause foodborne illness. Potential symptoms after eating pizza left out overnight include:
- Stomach cramps
- Nausea
- Vomiting
- Diarrhea
- Fever
- Headache
- Chills
- Weakness
The exact symptoms and duration depend on the particular bacteria or toxin involved. But food poisoning from spoiled pizza can definitely make you feel sick.
High Risk Groups
Some people are at higher risk of getting sick from eating old pizza or other mishandled foods. These high risk groups include:
- Young children
- Elderly adults
- Pregnant women
- Those with compromised immune systems
- People taking immunosuppressant drugs
Those in high risk groups should be especially cautious about eating pizza that’s sat out too long. Foodborne illness can be more dangerous for them.
Conclusion
In summary, it is not recommended to eat pizza that has been left out at room temperature overnight. The 2 hour danger zone rule applies to pizza as well.
Leaving pizza out for more than 2 hours allows bacteria such as Staphylococcus, Bacillus, Salmonella, and E. coli to multiply to hazardous levels. These bacteria continue producing toxins even if the pizza is reheated.
Consuming pizza left out overnight can cause symptoms of food poisoning including nausea, vomiting, diarrhea, and abdominal cramps. The bacteria and toxins cannot be reversed by microwaving.
For optimal safety and quality, leftover pizza should be refrigerated within 2 hours and eaten within 3 to 4 days. Storing pizza properly prevents bacteria growth and makes leftovers safe to enjoy.
