Home Hacks

8 Things That You Should Never *Ever* Put in the Microwave

Lobster did not make the list.

March 21, 2023
Photo by Bobbi Lin

The microwave—or as some professional cooks like to call it, “Chef Mike”—is one of the most useful tools in any kitchen. There are few (if any) appliances capable of reheating leftovers, poaching salmon, steaming sweet potatoes, and occasionally burning popcorn. While the list of foods you might want to cook in a microwave continues to grow (thank you, David Chang), because of what a microwave is—and how it works—there are certain things that never belong inside of it.

How Does A Microwave Work?

Microwave ovens create electromagnetic microwaves that are absorbed by food. Those microwaves cause water molecules in food to vibrate, creating the heat that cooks your food. For this process to work, microwaves must be able to pass through the container holding your food. Microwaves will pass through glass, paper, and ceramic objects, making them the preferred materials for microwave-safe cooking. However, microwaves do not pass through metal, making it problematic for the appliance.

Read Your Manual

Before we get into the list of what should never be placed in a microwave, it’s worth mentioning that every device is slightly different. Everything you need to know about your microwave can be found in its manual. There, you will find a detailed outline on what doesn’t belong inside your specific appliance. If you’ve lost your manual, identify the make and model of your microwave, then search for it online.

8 Things That Never Belong In Your Microwave

1. Aluminum Foil

Metal reflects microwaves, which can cause fires and ruin your appliance. If you often wrap leftovers in foil, make sure it is completely removed before reheating your food.

2. Any Kind of Metal

It’s worth repeating: Metal should never be inside your microwave. This includes silverware, and any plates, bowls, or spoons that have a metal rim. Not only is it dangerous, but it also impedes the microwave from actually heating your food.

3. Raw Spicy Peppers

When heated by microwave, raw spicy peppers release capsaicin (the compound that gives them heat) into the air. A microwave’s fan will blow the capsaicin directly into your face upon opening, which is potentially dangerous for your eyes and lungs. For reference, this is the same compound used to create the “hot” feeling in IcyHot—you don’t want that in your eyes.

4. Single-Use Plastic

Water bottles, plastic bags, and anything made out of cheap, flimsy plastic should never be microwaved because they could contain the harmful chemical, Bisphenol A (BPA). When melted, these materials could release the chemical into your food.

5. Styrofoam

Similar to single-use plastic, styrofoam will melt in your microwave and release chemicals into your food which have been linked to cancer.

6. Uncovered Sauces

Left uncovered, heated sauces will bubble and burst until they eventually splatter all over the inside of your microwave, potentially damaging the appliance’s interior. Always cover your sauces—your microwave shouldn’t look like a Jackson Pollock painting.

7. Nothing

Using your microwave when there's nothing in it can also cause problems. When there is nothing there to absorb the electromagnetic microwaves, that energy is directed back inside the appliance, potentially harming it.

8. Plain Water

Unlike water boiling on your stove, water that is heated beyond its boiling point in a microwave will not always bubble. However, when that seemingly calm water is disturbed—either by you picking it up or pouring something inside of it—the liquid can violently erupt, possibly injuring you and anyone nearby. According to the FDA, adding substances such as instant coffee or sugar to water before heating will greatly reduce this danger.

What’s something you’ve learned about your microwave recently?
Grab your copy

It's here: Our game-changing guide to everyone's favorite room in the house. Your Do-Anything Kitchen gathers the smartest ideas and savviest tricks—from our community, test kitchen, and cooks we love—to help transform your space into its best self.

Grab your copy

See what other Food52 readers are saying.

  • Smaug
  • adambravo
Paul Hagopian

Written by: Paul Hagopian

Content @ Food52


Smaug March 22, 2023
I don't know where the notion came from that microwaves only act on water came from, but it's not at all true. They act most strongly on fats, but, for instance, I warm up my empty coffee cup in the microwave every morning. One of the guys at Serious Eats apparently did some experiments with metal bowls in microwaves and showed they can be used; I didn't read about it and am not very interested; I suppose it depends on placement of the bowl- I find it easy enough to simply not do it.
Smaug March 22, 2023
Are these guys ever going to get an edit function?
adambravo March 21, 2023
I have boiled plain water to make hot chocolate (in a glass or plastic) for decades without a single catastrophe. And it always bubbles..