Quick Answer
It is not recommended to eat pizza that has been left out at room temperature for longer than 2 hours. After this time, bacteria can grow quickly and cause food poisoning. The maximum time pizza should be left out is 3-4 hours if kept in cooler conditions. Reheating until piping hot throughout can kill bacteria but doesn’t make unsafe pizza safe to eat.
How Long Can Pizza Sit Out?
Freshly cooked pizza can safely sit at room temperature for up to 2 hours. After this time, the risk of food poisoning increases as bacteria start to grow and multiply quickly in the moist, protein-rich environment of the pizza toppings.
Some experts give a window of up to 4 hours if the pizza is kept in a cooler place away from heat sources. However, this should be seen as the absolute maximum time, after which pizza should be thrown out.
The 2 Hour Rule
The 2 hour rule is the recommended maximum time to leave cooked foods like pizza sitting out at room temperature.
Food safety organizations like the United States Department of Agriculture (USDA) and FoodSafety.gov state that food should not be left out between 40°F and 140°F for more than 2 hours.
Bacteria grow most rapidly in this temperature danger zone, doubling in number every 20 minutes. To stay safe, discard refrigerated leftovers after 2 hours at room temperature.
Why Pizza Goes Bad Faster
Pizza often becomes unsafe to eat faster than other foods. This is because:
– It has a thick, dense crust that retains heat and keeps the interior at risk temperatures longer. The middle of a pizza can still be warm 4 hours after coming out of the oven.
– Lots of moisture from sauce and cheese creates ideal conditions for bacteria to thrive.
– Toppings like meat and veggies provide high protein and nutrients. Bacteria utilizes these to multiply rapidly.
So it’s always best to err on the side of caution and not let pizza sit out longer than 2 hours, or 4 hours max if the room is cooler.
What Happens If You Eat Pizza Left Out Overnight?
Eating pizza that has sat out at room temperature overnight poses a high risk of developing food poisoning.
Bacteria typically multiply to dangerous levels after being left out for longer than 4 hours in room temperature conditions. Consuming contaminated pizza after this time can lead to symptoms like:
– Nausea
– Vomiting
– Diarrhea
– Abdominal cramps
– Fever
Food poisoning usually develops within 6-48 hours after eating contaminated food and lasts around 1-3 days. It can be dangerous for those with weakened immune systems.
The longer pizza sits out past the danger zone time limit, the greater the chances that dangerous bacteria like Staphylococcus aureus, Bacillus cereus, Listeria or Salmonella may have multiplied to unsafe levels.
Reheating pizza left out all night will not make it safe by killing these bacteria. Their toxins will remain in the food and can still cause food poisoning.
Is Reheated 3 Day Old Pizza Safe to Eat?
Pizza that is 3 days old and has been continuously left out at room temperature for this whole time should not be eaten, even if reheated.
While thorough cooking can kill bacteria, it does not neutralize the dangerous toxins and waste products they leave behind in food. Even if the pizza looks and smells fine, these toxins can still cause foodborne illness if ingested.
Ideally, pizza meant for leftovers should be cooled within 2 hours and refrigerated. Pizza leftovers should be eaten within 3 to 4 days for best quality and safety.
Reheating pizza that is no more than 3 to 4 days old until it is piping hot throughout (165°F) can help make it safer but does not remove the risk entirely.
Tips for Safely Reheating Leftover Pizza
To reduce the risks of food poisoning from eating leftover pizza:
– Discard slices left out more than 2 hours. Do not reheat.
– Refrigerate uneaten pizza within 2 hours and use within 3 to 4 days.
– Choose thick crust slices which hold heat better. Thin crust dries out.
– Reheat refrigerated pizza until steaming or 165°F. Pizza with lots of toppings may need longer heating times.
– Use the oven or a skillet on medium heat rather than the microwave for more even reheating.
– Consume reheated pizza immediately. Do not let it sit out again or re-refrigerate after reheating.
Can You Still Eat Pizza with Mold on it?
It is risky to eat pizza that has begun growing mold. Even if you cut the moldy areas off, the fungi may have spread invisible roots deeper into the food that could contain toxins and cause illness.
Signs pizza has spoiled and become dangerous to eat include:
– Visible mold growth. This appears as fuzzy spots or stringy tendrils on old pizza.
– An unpleasant odor, sliminess, or change in color.
– Drying out until the pizza becomes stale, crumbling, and hard.
Mold generally appears after 3 or 4 days at room temperature or over a week in the refrigerator as pizza leftovers age. It means the food has passed its use by date and potential spoilage bacteria or pathogens may be present. Eating moldy pizza could result in digestive upset or food poisoning.
Even if refrigerated and free of mold, leftover pizza should be thrown out after 7 days as quality and safety decline. For optimal freshness and flavor, finish pizza within 3 to 5 days.
How to Store Pizza Leftovers
To get the most out of leftover pizza and prevent foodborne illness:
– Allow cooked pizza to cool for about 30 minutes before refrigerating. Covering the box with foil allows air to escape so the crust stays crisper.
– Divide up pizza into smaller portions or slices to chill faster. Refrigerate within 1 to 2 hours.
– Use shallow, airtight containers to store pizza. This prevents drying out.
– Consume refrigerated leftovers within 3 to 4 days.
– To freeze pizza, wrap tightly in plastic wrap then foil. This prevents freezer burn. Frozen slices will keep for 2 to 3 months.
– When reheating frozen pizza, defrost first in the refrigerator. This helps maintain texture and prevent sogginess.
Proper cooling, storage, and reheating of leftover pizza reduces the risk of food poisoning. But when in doubt, remember it’s better to be safe and throw it out.
Can Old Pizza Make You Sick?
Yes, eating pizza that is past its prime can make you sick by causing foodborne illness. Sickness can occur from:
– Bacteria like Staphylococcus, Listeria, or Salmonella growing on pizza left out too long at unsafe temperatures.
– Toxins produced by these bacteria as they multiply. Even if the bacteria are killed by reheating, the toxins remain.
– Molds that colonize old, spoiled pizza produce mycotoxins that can cause illness.
– Unhealthy ingredients that have begun to break down and turn rancid.
Symptoms typically start within hours or days after eating contaminated old pizza. Food poisoning causes:
– Nausea and vomiting
– Abdominal cramps and diarrhea
– Headache and fever
– Fatigue and weakness
In severe cases, doctor visits may be required for dehydration or infections. Those with compromised immune systems like children, elderly, pregnant women, and those managing chronic illnesses are most at risk.
To avoid getting sick, stick to the 2 hour room temperature rule for pizza and reheating only refrigerated leftovers within 4 days. Discard any pizza that smells, looks, or tastes unpleasant.
Tips for Eating Leftover Pizza Safely
Here are some top tips for handling and consuming leftover pizza safely:
Refrigerate Promptly
Refrigerate uneaten fresh pizza within 2 hours, or 1 hour if the room is hot (over 90°F). Divide into smaller portions so it chills rapidly to below 40°F.
Store Correctly
Keep leftovers in shallow airtight containers. This prevents drying out and stops mold growth.
Eat Soon
Eat refrigerated pizza within 3 to 4 days for optimum safety and quality. Discard any slices with an off smell or appearance.
Reheat Thoroughly
When reheating pizza, make sure it reaches 165°F throughout. Check it is steaming hot.
Use Safe Methods
Quick microwave reheating can leave cold spots. The oven or skillet method heats evenly throughout.
When In Doubt, Throw It Out!
Don’t take risks with pizza left out overnight or that looks or smells bad. Remember, safety first.
Conclusion
Pizza is a popular food that’s always better freshly cooked. But enjoying delicious leftovers poses some safety considerations. Bacteria can multiply quickly on pizza left out at room temperature for over 2 hours. Reheating old pizza reduces but doesn’t eliminate risks.
For the best results, refrigerate pizza within 2 hours after cooking and consume within 3 to 4 days. When reheating, ensure slices are piping hot throughout. It’s always advisable to be cautious and discard pizza that seems at all spoiled or questionable. Follow the pizza storage and handling rules to safely enjoy leftovers without getting sick.
