The microwave is the most used and least understood appliance in most kitchens. It has been a household staple for 50 years, and yet most people have never thought carefully about what actually should not go in one. Some foods create genuine safety hazards: explosions, fires, toxic fumes, dangerous hot spots in food that looks heated through. Others are simply ruined in ways that are permanent and entirely avoidable. A few surprises are on both lists.
What foods should you never microwave?
The short answer: Eggs in the shell, grapes, hot peppers, high-proof alcohol, non-microwave-safe plastics, frozen meat you are not cooking immediately, stuffed poultry, and fried foods should never go in the microwave. Some create fire or explosion hazards. Others create food safety risks through uneven heating. Others are simply destroyed by the process in ways that cannot be undone.
For how to store these foods correctly before cooking, see our Food Storage Guide.
Foods You Should Never Microwave: At a Glance
Eggs in the shell
Grapes
Whole hot peppers
High-proof alcohol
Frozen meat (not cooking immediately)
Stuffed poultry
Non-microwave-safe plastics
Fried foods
Small whole fruits (cherry tomatoes, blueberries)
Shellfish in the shell
Carrots and certain root vegetables
Breast milk and formula
Key Takeaways
Eggs in the shell can explode in the microwave, mid-cooking or after removal. The explosion can cause serious burns, including if the egg erupts in your hand or mouth after heating.
Grapes create plasma when microwaved, a burst of superheated ionized gas that can damage the interior of your microwave and cause fires. The 2019 Nature paper that explained this mechanism confirmed it destroys microwaves.
Microwaving whole hot peppers vaporizes capsaicin, the compound responsible for heat. The invisible cloud released when you open the door can cause severe eye irritation, coughing, and throat burning.
High-proof alcohol releases flammable vapor in a sealed microwave cavity. A stray spark can ignite it.
Microwaves penetrate food to a depth of only 1 to 1.5 inches, according to USDA FSIS. This means dense or stuffed foods have cold spots where bacteria survive reheating even when the surface reads 165 degrees Fahrenheit.
Non-microwave-safe plastics can leach chemicals including BPA into food when heated. Use glass or ceramic instead.
Why Microwaves Behave the Way They Do
Understanding a few basics makes the list below make sense. Microwaves work by emitting electromagnetic radiation that excites water, sugar, and fat molecules in food, generating heat through that molecular friction. They do not heat food from the outside in the way an oven does. They penetrate to a depth of about 1 to 1.5 inches, per USDA FSIS, with the rest of the food heating by conduction from that zone outward. This creates two problems that come up repeatedly on this list.
The Two Core Problems
The first is steam entrapment. Foods with sealed exteriors
