11 Things You Should Never Put In The Microwave

When you are constantly on the move, getting things done quickly becomes a top priority—especially when it comes to food. But hold up! Before you reheat last night’s leftover lasagna, you should know your microwave isn’t designed to withstand everything. 

Although you may not realize it, your microwave puts in just as much work as you do. Treat it right with some know-how of what not to put in the microwave. 

Microwave safety 101: What’s hot and what’s not

An essential part of microwave safety is knowing what not to put in your microwave. Ready for our list of the most common microwave don’ts? Here are a few things you should NEVER put in the microwave:

1. Aluminum Foil

Sparks might fly in romance, but in your microwave? Hard pass. The metal interior of your microwave reflects radio waves. When aluminum foil joins the party, it can be a recipe for fires and a very unhappy appliance. 

Instead of casting a reflection of your face, the metal reflects radio waves or microwaves. The radio waves emit electromagnetic energy, warming up your items. When you place metal inside a microwave, the waves are reflected off of the item, causing the aluminum foil to burn rapidly and ignite. So, next time you’re tempted to toss that wrapped leftover into the microwave, think twice and opt for a microwave-safe container instead. 

2. Paper Bags

Not all paper bags are created equal. That bag of tasty popcorn slightly differs from the brown paper bag you use to carry your lunch. Popcorn bags are equipped with susceptors, a material made to consume the radio waves produced by microwaves. 

Typical paper bags, such as those used in grocery stores, do not have susceptors and can release toxins and fumes when warmed up. Because microwaves produce heat so quickly, the bag could catch fire. So, if you’re wondering what is not microwave-safe, steer clear of ordinary paper bags.

3. Plastic Bags and Plastic Containers

It’s safe to say you’ll want to keep all grocery store bags out of the microwave. When heated, 

plastic releases Bisphenol A, or BPA, an organic compound used to make plastic clear, and phthalates, which allows it to be supple. 

So, unless you’re interested in adding a side of chemicals to your leftovers, transfer your food to something else. It’s a simple rule of thumb in the world of microwave don’ts: when in doubt, opt for glass.

4. Travel Mugs

Typically constructed of plastic or steel, a travel mug should not make its final destination into your microwave. Because of the metal that’s part of your microwave’s construction, steel cups will inhibit your beverage from being heated and potentially cause friction from the energy being emitted. 

For plastic mugs, check the labeling to see if it is “microwave-safe”; otherwise, it’s best to keep your travel mugs on the move. It's worth the extra effort to heat your coffee in a microwave-safe mug and transfer it to your go-to, to-go mug.

5. Your Favorite Shirt

You woke up ready to take on the world today. To commemorate the occasion, you’ve decided to wear your lucky shirt. The shirt is fresh out of the washer and needs to dry, but last night’s load is still taking up space in your dryer. Looking around, you spot your microwave. Microwaves warm things. Warm means dry. You need a dry shirt. All these things make sense. It may seem like your best option, but it’s not.

So the next time you wonder what materials are not microwave-safe, remember that your lucky shirt tops the list. Save your shirt and your microwave. Wait for the dryer; you’ll be glad you did.

6. Hard-boiled eggs

Recipes are popping up everywhere, requiring a mug, a few minutes, and a microwave. Because microwaves cook at such high temperatures, trying to cook an egg would create abundant steam within its shell. The steam rises in the egg, and quicker than you can say “cracked,” you’ll likely have an egg-y explosion to clean up.

7. Hot peppers

Who would have thought that a microwave had the power to bring you to tears? If you’re interested in adding a little heat to your heat, using a microwave to warm up your peppers isn’t such a hot idea. 

Not only can they spark and cause a fire, but when you open the microwave, chemicals released from the peppers may cause you to choke and even burn your eyes. It's a process similar to pepper spray, so keep that in mind before popping those peppers in your microwave.

 8. Styrofoam in microwave

Though restaurant leftovers have lived in them for what seems like an eternity, polystyrene foam containers, commonly known as Styrofoam, don’t belong in your microwave. Not only is the material difficult to biodegrade, but when heated in the microwave, the foam may begin to melt, releasing chemicals into your food. 

If the contents inside are hot enough, your food could melt through the packaging. On the plus side, some polystyrene foam containers can be used in your microwave; just make sure you read before warming.

9. Lidless containers

Unless you’re really into making a day out of cleaning tough messes, then it’s recommended you cover your food before placing it in the microwave. The heat released while warming up that plate of spaghetti can cause your uncovered dish to simmer, jump around, and even detonate. Avoid a marinara meltdown. Keep dishes covered using a microwave cover or microwave-safe material.

10. Chinese takeout boxes

Thinking about warming up last night’s tasty General Tso’s spicy chicken? Be sure to take it out of the box. Typically, Chinese takeout boxes include a thin metal handle, which doesn’t fare well with a microwave. When heated, the wiring may cause sparks or flames. Worst of all, you just wasted an order of General Tso's chicken.

11. Nothing at all

We’ve all been there. You have your mind on one thing and then begin doing another, or maybe you were just in a “let’s see what happens” sort of mood. Powering up your microwave without placing anything inside is a sure way to ruin your appliance. 

In fact, it could be blown to smithereens. The microwaves released have to have somewhere to go. Without a destination, the waves bounce off each other and are absorbed by the microwave, causing it to combust. That’s why running an empty microwave is on the list of microwave don’ts.

Microwave mishaps? Don’t Worry, Be Warranty.

When it comes to microwaves, your best bet is to keep it simple. Remember, they were made to heat your food, not complicate it. The next time you consider putting something in the microwave you’re unsure about, talk it over with your oven or stove. They miss you.

But what if your microwave decides to retire early despite my best efforts? Don’t sweat it. That’s where a home warranty plan from American Home Shield comes in. Our appliance warranty coverage includes protection for built-in microwaves, protecting you from expensive, unexpected breakdowns.

Want to learn more about protecting your home's appliances and systems? Check out our home warranty plans and appliance coverage options. Because in the land of homeownership, being prepared is always in style.

AHS assumes no responsibility, and specifically disclaims all liability, for your use of any and all information contained herein.