Accidentally Left Frozen Pizza Out Overnight, Now What?

Have you committed the ultimate sin of leaving your favorite frozen pizza out overnight and fear what may befall you and your family?  Although many have eaten pizza that has been left out overnight, is it actually safe to do so?  Just a few bites of pizza left out over the late hours of the night can’t hurt, especially when it tastes so good leftover, right? So what happens if you accidentally left frozen pizza out overnight?

Contrary to what some may believe, eating leftover frozen pizza is actually advised against.  Eating a frozen pizza that was left out overnight before it’s cooked could give you food poisoning.  Thawed frozen pizza can be a breeding ground for certain strains of bacteria in as little as two hours, and cooking the pizza may not kill them.

Well, that’s kind of a bummer- but information gained is still a win.  This article will cover why frozen pizza left out overnight should be thrown out and not cooked, ways to prevent bacteria from growing on your beloved frozen pizzas in the future, and what’s the max time it should be left out. 

What Happens To Frozen Pizza When It’s Left Out Overnight?

What happens to frozen pizza when it’s left out overnight largely depends on the toppings, ingredients of the dough, temperature of your home and the amount of time it was left out.  When you thaw a frozen pizza, it goes from approximately 32 degrees Fahrenheit to approximately 65 degrees Fahrenheit, making it very vulnerable to contamination.

Even though some of us would logically think that when the thawed contaminated pizza is cooked in the oven the high temperatures would kill all of the bacteria, this is not always the case.  This is because even thawed frozen pizza that’s been cooked has the chance of carrying toxins that have been dispelled by the once-living bacterial organisms.  Yuck!

Eating frozen pizza left out overnight can cause so much bacterial replication that it can make you very ill because their colonization exacerbates in warmer temperatures.  Since the pizza was originally uncooked, it was already susceptible to bacterial growth the moment you put the pizza on your counter and forgot about it.

Some frozen pizzas contain eggs in their ingredients which can if left out at room temperature begin to breed its own strains of bacteria such as salmonella.  Another thing to consider is that freezing any food item will not kill any bacteria, it just prevents any bacteria once present on the pizza from continuing to multiply and spread. 

Symptoms Of Ingesting Frozen Pizza That Was Against Left Out Overnight

If you happen to cook and eat frozen pizza accidentally left out overnight, there are a number of symptoms you may experience, or you may experience none at all.  Some include:

  • Upset Stomach
  • Stomach Cramps
  • Nausea
  • Vomiting
  • Diarrhea
  • Fever
  • Loss Of Appetite 
  • Weakness
  • Headache

Some symptoms are more severe:

  • Bloody Diarrhea
  • Bloody Urine
  • High Fever Above 102 Degrees Fahrenheit
  • Frequent Vomiting (to where you cannot hold down fluids)
  • Signs Of Dehydration (little or no urination, very dry mouth and throat or feeling dizzy when you begin to stand)
  • Prolonged Diarrhea (lasting more than 3 days)
  • Extreme Abdominal Pain
  • Blurry Vision
  • Tingling In Arms

Severe cases of food poisoning can also leave you with some pretty unfavorable conditions, including chronic arthritis, neurological and cerebral damage, and kidney failure via hemolytic anemia.  Therefore, it may be best for you if you abstain from eating and cooking that still delicious looking (but not so frozen) pizza.

The Hidden Dangers Of Frozen Pizza    

To some people’s shock, frozen pizza has had its fair share of damage dealing to humans worldwide.  In some reports, frozen pizzas have been under investigation for contamination before they’re even baked.  As a matter of fact, E. Coli linked to frozen pizza has been investigated in more than 75 cases, all in young adults and children. 

There have been cases in France of a specific frozen pizza product named “Fraich Up” by a brand named Buitoni (owned by Nestle) directly linked to food poisoning.  Even after thorough investigation, Nestle could not find the exact causes of contamination within the factories they were being produced.  The product was later recalled despite no serious cases.

In other brands of frozen pizzas, more cases of E. coli have been found.  A popular brand called Totino’s and another popular brand named Jeno’s were both found to have contaminated pepperoni.  Although these cases were not reported to be very severe, it still advocates for the fact that cooking an already thawed frozen pizza should be considered a risky act. 

accidentally left frozen pizza out overnight

What Toppings And Ingredients Are Most Susceptible To Bacteria Growth?

There are some ingredients that frozen pizza can contain that are especially susceptible to bacterial contamination and growth, including:

  • Eggs
  • Pepperoni
  • Hamburger
  • Chicken
  • Shrimp
  • Ham
  • Cheese

As you can see from the list above, the ingredients most commonly on pizza that are most susceptible to bacterial growth are derived from animals.  This makes sense, as the CDC mentions animal products are most likely to cause food poisoning in general.  Fruits and veggies can also become contaminated, but this is less likely to happen.

How Long Can A Frozen Pizza Be Left Out?

How long a frozen pizza can be left out at room temperature depends on a few factors such as the temperature of the room, the location it’s left in, its ingredients, how much bacteria was present on the pizza before it began to thaw, and even if it has a covering on it or not (such as still being in the wrapping or covered in foil.

The rule of thumb for leaving out a frozen pizza at room temperature is to never consume it if it has been left out longer than two hours.  Some recommend less time (one hour) and then pitching it after that.  It depends upon how warm the room is in which it was left- if it was left in a warm room, you should probably throw it away after one hour.    

Preventing Bacteria From Growing On Your Frozen Pizza 

There are a number of things consumers can do to prevent the risk of food poisoning when preparing, cooking and eating their frozen pizzas.  The first thing you should be vigilant in is if you don’t plan on consuming your frozen pizza right away, you should store it in the freezer until the time you plan on cooking it. 

Another thing you can do to prevent the buildup of bacteria on your frozen pizza is to only remove it from the freezer at the very moment you plan to insert it into the oven.  Don’t get it out while your oven is preheating- this will only lead to your frozen pizza thawing and eventually breeding all different kinds of bacteria, which is exactly what we want to avoid.


Although we may be a little disappointed in learning that the tantalizing frozen pizza we forgot to cook last night spent its last few moments in its lonesome growing bacteria like a petri dish, at least you didn’t become a bug hotel.  Frozen pizza is certainly susceptible to all kinds of quirky bacteria, so it’s of utmost importance to follow basic food safety guidelines when cooking it. Hope this has helped after leaving you’re pizza out over night.

Latest post’s

Is Pizza A Fast Food?

Pizza for Sore Throat

Sam Brett

Sam Brett is the founder and editor of Pizzachefhq, a pizza enthusiast who writes about what he's learned on the way of being a pizza creator and sharing his advice, tips, and research.

Recent Posts