This Is The Only Way You Can Put a Styrofoam Coffee Cup in the Microwave

Styrofoam Coffee Cup

Since the invention of microwave ovens in 1946, they have been part of millions of households in the United States. Materials such as metals and certain plastics should not be put in a microwave.

Such products are potentially harmful to foods and consequently to one’s health.

Can you put a Styrofoam coffee cup in the microwave? Yes, but only if your Styrofoam coffee cup is microwave-safe. However, it is still best to not microwave Styrofoam cups regardless of whether they are microwave-safe.

Read on before you put your coffee cup in the microwave. This post will give you insight into the risks and consequences of heating coffee in a Styrofoam cup and how they could overshadow its advantages.

What Is Styrofoam?

Styrofoam is a term that is a trademark of the Dow Chemical Company. It refers to the type of polystyrene foam that is widely used in the construction industry.

In some nations, the term refers to the type of expanded polystyrene foam injected into molds. These molds produce plastic pots, bowls, and coffee cups.

The composition is around 95% air, which makes it extremely light in weight. Styrofoam is a large insulator with an R-value of approximately R-5 per inch.

With the high air content, it is practically unsinkable. Styrofoam does not lose its form or break down over time.

These containers are common because they are inexpensive and serve as a good insulator. Styrofoam can keep your food and drink warm.

While polystyrene containers have been common in the past, they have slowly been outlawed in many cities in the United States.

This material poses a threat to one’s health and the environment.

Environmentally speaking, containers do not decompose immediately and are difficult to recycle.

Animals can even confuse them for food and eat them. From a health standpoint, they include a compound called styrene, which has been related to cancer in animal and human research.

Types of Styrofoam Containers

  1. Coffee Cups. Styrofoam coffee cups are commonly used to serve hot cocoa and coffee.

  2. Take-out Containers. They are also used for dining out or taking leftovers home. It’s much easier to put the whole thing in the microwave for five minutes.

  3. Styrofoam Plates. These are inexpensive substitutes that are suitable for parties. Also, they are cheap and disposable and you can use them to reheat meals the next day or for people who have come late to the party.

  4. Traditional Cup Noodles. Generally, there are two sets of instructions. Each of them adds hot water. However, the other may recommend filling with water from the tap and sticking the whole thing in the microwave.

Frequently Asked Questions About Styrofoam

Can You Microwave Styrofoam?

There is some doubt about microwaving polystyrene foam cups. They contain a chemical called styrene, which has been connected to cancer in human and animal research.

When food or beverages are microwaved in polystyrene or plastic containers, the substances used can leak into the food.

The Food and Drug Administration (FDA) controls and checks the quality and use of cups and plates in microwave ovens.

This ensures that all polystyrene or acrylic products with a microwave-safe sticker have been checked for safety in the microwave.

Stop microwaving food in polystyrene containers that are not microwave-safe, as their protection is not guaranteed. This precaution is not exclusive to microwaves; it extends to other heating methods as well.

Is Styrofoam Flammable?

Real polystyrene is highly flammable, but the use of chemical additives makes it more flame-proof.

It also poses a fire danger. The possible consequences of ingesting the components of heated polystyrene include:

  • Eye and gut soreness
  • Headaches 
  • Hearing problems
  • Clinical depression
  • Dysfunction of the central nervous system
  • Infection

Does Styrofoam Melt?

Yes, it melts in acetone and when microwaved too long or with extremely hot food or substances.

Hot foods and liquids start a partial breakdown of the Styrofoam, causing some toxins to be absorbed into our bloodstream and tissue.

Can You Get Cancer from Microwaving Styrofoam?

Styrofoam melts in acetone and when microwaved for too long or with excessively hot food or substances.

Polystyrene includes the poisonous compounds styrene and benzene, potential carcinogens, and neurotoxins harmful to humans. Hot foods and beverages are now beginning a partial degradation of Styrofoam.

Benefits of Microwaving Styrofoam

Microwaving Styrofoam can also provide a few benefits.

  • Cost-effectiveness
  • Convenience
  • Disposability

How to Tell if Styrofoam Is Microwave Safe

Check the icon at the bottom of the container. A microwave-safe icon is typically a microwave with a few wavy lines on it.

If the cup has a #5 on it, it is made of polypropylene, PP, so it is usually known to be microwave safe.

PS, polystyrene, Styrofoam, and #7 are not suitable for microwave use. Many containers and clamshells are made of foam for their insulation properties.

They keep food warm during travel, so you don’t have to reheat it. Be sure to place the food on a plate or other healthy container before zapping it in the microwave.

How Can I Microwave Styrofoam?

When heating a meal inside Styrofoam, the shape can be altered, and the meal may be ruined when the container melts.

Toxic compounds that leak out are hazardous to the body. Some Styrofoam containers are made specifically for microwave ovens; they are heat-friendly.

The heating temperature for these containers should not exceed 175 degrees. However, some are still considered safer than plastic containers.


Be mindful of the things you put in your microwave oven for the sake of your health and safety. There is little evidence that it’s safe to place Styrofoam in the oven.

In fact, I don’t recommend that it be heated at all. Your well-being is more important than convenience.

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