Can You Microwave Styrofoam new
What to know

Can You Microwave Styrofoam?

Some people had to learn the hard way that they can’t simply put just anything inside their microwave to heat it up. Certain containers are safer to put into the microwave than others. The earliest warnings of such nature were that microwaving plastic could release cancer-causing chemicals or dioxins into the food you’re heating or reheating up. Dioxins aren’t present in the plastics themselves but instead from burnt garbage, metals, wood, and plastics.

As long as you’re not burning anything with your microwave, you should be safe from dioxins. On that note, is styrofoam microwaveable or microwave-safe? Can you microwave styrofoam? 

You may also like: The Ultimate Guide to Choosing a Microwave Oven that Best Fits Your Needs

Is Styrofoam Microwave-Safe?

Despite popular belief to the contrary, you can safely use polystyrene containers like Styrofoam or styrofoam with your microwave. Just check the label if it’s microwave safe and follow instructions on proper reheating. Otherwise, you’ll be told it isn’t microwave-safe or there won’t be any label and you should err on the side of caution and just put your food in a microwave-safe container like ceramics and the like. 

  • Can You Put Styrofoam in the Microwave? Styrofoam and polystyrene foam are great for keeping cold food cold and hot food hot. They can also protect the contents within or hold their shape when used as packaging. However, when deciding to put your takeout food into the microwave instead of putting them in your fine china dishes first instead, it’s important to note that there are microwavable and non-microwavable types of styrofoam that will outright label themselves as such for your convenience.
  • Traditional Styrofoam: Styrofoam remains stable during normal use. However, when exposed to heat or high temperatures, the material might break down and melt. This in turn releases toxic chemicals contained within the foam, which in turn could contaminate your food and/or drink. Sure, they can withstand high temperatures as in the case of a cup of hot coffee. However, microwave heat can get so hot that the Styro could catch fire, releasing carcinogenic compounds that render your food toxic when eaten.
  • Microwave-Safe Styrofoam: This styro alternative is manufactured with safer materials that can withstand microwave heat in particular. It also has lower levels of dangerous toxic compounds inside it. It’s specifically designed to withstand high temperatures so that it won’t catch fire or melt inside your microwave. A Styro container should display a label saying it’s microwave safe before you can dare put it inside your microwave. It’s the same with certain clear plastic containers, come to think of it.
  • The Concern Regarding Microwaving Styrofoam: There is some concern about microwaving traditional polystyrene foam containers. As mentioned, they contain cancer-linked styrene. Additionally, unless it’s indicated that the Styrofoam being used is microwave-safe, you shouldn’t microwave them at all since when they catch fire and spread VOCs (volatile organic compounds) on top of styrene, they become extra toxic to you and the food you eat off of them.
  • A “Leak” Could Occur: As a rule of thumb if the Styrofoam container doesn’t claim that it’s microwave safe then don’t microwave it. This is because some particularly cheap Styro containers made of plastic or polystyrene can have substances used in making them leak into your food or drinks. This is especially true when it comes to foods that contain loads of fat, such as cheeses and meat. This is also applicable to dairy products like milk as well, in case you mix that with your foam cup of coffee.

styrofoam microwave

What is Styrofoam Supposed to be Anyway? 

Styrofoam was originally not a generic term for polystyrene foam. It was instead a trademarked term by the Dow Chemical Company. It’s like how Hoover vacuums became synonymous with vacuums, Band-Aid bandages became synonymous with plastic strips, and Xerox became synonymous with photocopiers. It’s a variant of the polystyrene foam commonly used in the building industry.

  • Disposable Styrofoam: The foam is referred to in this article discussing its safeness when microwaved is a type of expanded polystyrene foam used commonly for food or electronics packaging. It’s disposable foam injected into molds in order to create takeout containers for restaurants and fast food places. This foam can also come in the form of Styrofoam coffee cups, packaging peanuts to keep your packages safe, and plates for eating. This type of foam is mostly known as Styrofoam in countries such as the U.S. and Canada.
  • The Popularity of Styro: Styrofoam containers are popular in that role because of their affordability. In the case of Styro coffee cups, they’re also well-known insulators too. This means that they’re excellent when it comes to retaining heat and keeping beverages and foodstuffs hot. This should mean that they’re microwave-safe, right? At the right timing and temperature, as long as you don’t end up burning them or setting them ablaze, they should be completely non-toxic, correct?
  • Banned in Several Cities and States: In the past, Styrofoam containers were popular. However, as time passes, more and more of them have become banned in the U.S., like in the case of Seattle and San Francisco. This is because they’re an environmental hazard. They’re also the root cause of some health concerns due to their toxicity when burned and the difficulty of disposing of them as in the case of any cheap but long-lasting, non-biodegradable plastic.
  • Styro is an Environmental Hazard: It’s difficult to recycle Styrofoam. Furthermore, the containers don’t decompose easily compared to paper containers. Furthermore, they’re a hazard to animals that might consume them since the plastic might remain in their digestive system until their death due to blockage and whatnot. They’re as dangerous to wildlife as plastic straws are to dolphins and a myriad of sea creatures who eat them.
  • The Compound Named Styrene: The danger of microwaving polystyrene foam of the Styrofoam variety is the fact that this cheap packaging material contains styrene. Styrene has some links to caners in human and animal studies, hence the banning of the use of Styrofoam and the rise of paper bags and containers. At least paper is a renewable and recyclable resource even though it has its own downsides like deforestation and how long it takes for a tree to grow just for it to be used for paper towels and packaging. 

Things to Remember About Microwave Usage

Before microwaving your microwave-safe Styrofoam that’s hopefully not damaged in any way, here’s a couple of things to remember when it comes to safe microwave usage.

  • Err on the Side of Caution: Put your food or drink in glass or ceramic containers labeled safe for microwave oven usage if you’re still concerned about toxic compounds getting into the care of Styro containers or plastic wraps.
  • Don’t Allow Styro to Melton Food: Don’t allow plastic wrap, traditional Styro, or damaged Styro to touch your food when it’s being microwaved. They might melt and contaminate what you’re supposed to eat.
  • Styro Alternatives: Better alternatives for containers are a domed container that fits over your bowl or plate as well as kitchen parchment paper, wax paper, or white paper towels. Again, ceramic plates and china are the best options for microwave ovens.
  • Most Containers Aren’t Microwaveable: Most Containers Are Not Microwave Safe: Most Styro takeout containers, water bottles, and plastic tubs or jars made to hold foods such as mayonnaise, mustard, and cream cheese as well as whipped cream, yogurt, and margarine aren’t microwaveable.
  • What Makes Microwaveable Trays Work? Takeout dinner trays and containers of the microwaveable variety are made for one-time use only. You can’t use them multiple times compared to dinner plates and bowls. The packaging will say as much.
  • Damaged Containers are a No-No: Even if a container is microwaveable, you shouldn’t use it if it’s damaged, cracked, scratched, or old. Any container that’s been used many times can have many plasticizers leak out altogether, especially in the case of Styrofoam.
  • Don’t Microwave Plastic Bags and Paper Bags Either: Like with Styro, you shouldn’t microwave plastic storage bags or grocery store plastic bags. The problem with paper bags and containers is that they could disintegrate due to the heat and the grease from the food.
  • Vent the Container: When microwaving a microwave-safe Styrofoam container, you should vent the container or leave the lid ajar. Don’t seal the container. Lift the edge of the cover to prevent a pressure-cooker effect.
  • Transfer to a Plate: Ultimately, you should transfer food from a container to a ceramic plate because the plate is your safest bet when it comes to heating your food without the risk of contamination.


So can you put Styrofoam into your microwave for heating? The answer to that is a resounding “no” by default unless the container specifically specifies it’s microwave-safe. It’s best to err on the side of caution and transfer your food and drink in a microwave-safe container like your china and the like.

Only put a container that’s clearly marked as microwave-safe inside your microwave for the sake of reheating. Additionally, if your microwave-safe Styrofoam has any signs of damage, you can avoid putting it inside your machine anyway despite the label saying it’s safe. It’s because it’s been compromised and only whole, undamaged microwave-safe Styro can be considered as safe for reheating inside your microwave. Even then, don’t heat up your food for too long on the container regardless. If you’re going to reheat it for longer than a couple of minutes, it’s best to transfer the food or drink inside ceramic cups, bowls, and plates.


  1. Microwaving food in plastic: Dangerous or not?“,, September 20, 2017
  2. Appliance, “Can You Put Styrofoam in the Microwave? Reheat Food Safely“, March 26, 2019
  3. Ryan Raman, MS, RD, “Can You Microwaves Styrofoam, and Should You?“, com, January 7, 2020

Through the years, the microwave oven has become a standard appliance for all homes. It is safe to say that there is no home without a microwave oven. If you are looking for a microwave oven that best fits your needs, You find the right website.

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