The microwave is the most used and least understood appliance in most kitchens. It’s been a staple for 50 years, and yet most people have never thought about what shouldn’t go in it. Some foods create real safety hazards: explosions, fires, toxic fumes, dangerous hot spots in foods that appear heated. Others are simply ruined in a permanent and completely avoidable way. A few surprises are on both lists.
What foods should you never microwave?
The short answer: Shell eggs, grapes, hot peppers, heavy duty alcohol, plastics that are not microwave safe, frozen meat that you do not cook immediately, stuffed poultry, and fried foods should never be microwaved. Some create fire or explosion hazards. Others create food safety risks due to uneven heating. Others are simply destroyed by the process in an irreversible manner.
To learn how to properly store these foods before cooking, see our Food Storage Guide.
📋 Foods You Should Never Microwave: A Quick Look
🥚 Shell eggs 🍇 Grapes 🌶️ Whole hot peppers 🍶 High-strength alcohol 🧊 Frozen meat (does not cook immediately) 🍗 Stuffed poultry 🛢️ Non-microwaveable plastics 🍟 Fried foods 🫐 Whole berries (cherry tomatoes, blueberries) 🦪 Shell shells 🥕 Carrots and some root vegetables 🍼 Breast milk and infant formula 🔑 Key takeaways
Shell eggs may explode in the microwave, halfway through cooking, or after being removed. The explosion can cause serious burns, especially if the egg bursts in your hand or mouth after being heated. Grapes create plasma when microwaved, an explosion of superheated ionized gas that can damage the interior of your microwave and cause fires. The 2019 Nature paper explaining this mechanism confirmed that 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 vapors into 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 the USDA FSIS. This means that dense or stuffed foods have cold spots where bacteria survives reheating even when the surface reads 165 degrees Fahrenheit. Plastics that are not microwave safe can leach chemicals, including BPA, into food when heated. Instead, use glass or ceramic. 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 this molecular friction. They don’t heat food from the outside like an oven does. They penetrate to a depth of about 1 to 1.5 inches, according to the USDA FSIS, with the rest of the food heated by conduction from this area outward. This creates two problems that come up repeatedly on this list.
🔬 The two fundamental problems
The first is vapor trapping. Foods with a sealed exterior (shells, skins, sealed packages) trap steam produced by internal water molecules as they heat. With nowhere to go, the pressure builds until the food breaks. This is why eggs explode, whole fruits burst, and shellfish are dangerous. The second is uneven heating. Dense or irregularly shaped foods develop hot spots and cold spots. The surface can reach a safe temperature while the interior remains in the bacterial danger zone. This is the specific risk that the USDA warns of with frozen meat thawed in the microwave and not immediately cooked, as well as with stuffed poultry.
Foods You Should Never Microwave 1. Eggs in the shell Whole eggs in their shells should never be microwaved, whether raw or hard-boiled. Raw eggs produce steam quickly as the water inside heats up, and the shell can’t release the pressure quickly enough. The result is an explosion that coats the inside of your microwave in egg and, if the egg is removed before it explodes, can burst in your hand or on your plate. Hard-boiled eggs pose the same risk for a different reason: Even after cooking, residual moisture inside the yolk can overheat and turn into steam when the egg is reheated. The American Egg Board warns that hard-boiled eggs should not be microwaved in their shells.
⚠️ The risk of mouth explosion
Several food safety sources document cases of hard-boiled eggs appearing to reheat normally in the microwave, but then exploding when bitten. The superheated steam inside the yolk is instantly released when the outer surface is pierced. This can cause severe burns inside the mouth and throat. Always cut or chop hard-boiled eggs before reheating them in the microwave.
Safe alternative: Reheat sliced or chopped cooked eggs in a covered skillet over low heat. For a dish that makes wonderful use of eggs cooked the next day without the risk of reheating, our crustless vegetarian quiche And Greek meze platter both work well served at room temperature. For complete advice on egg storage, see do eggs go bad.
2. Grapes Microwaving grapes is one of the most documented microwave risks in food science, and the mechanism was only fully explained in 2019 when researchers published their results in the journal PNAS (Proceedings of the National Academy of Sciences). When a grape (or a grape cut in half with the halves touching) is microwaved, electromagnetic fields concentrate between the two sections due to the size of the grape, its water content, and the way its skin focuses microwave energy. The result is a plasma fireball: an explosion of superheated ionized gas that produces visible sparks, intense heat, and a realistic risk of damaging the microwave’s interior or starting a fire. The researchers who documented this went through 12 microwaves during the process.
The same phenomenon can occur with other small, spherical foods with high moisture: cherry tomatoes, blueberries, and quail eggs all have similar geometry and water content.
Safe alternative: If you want to use warm grapes, roast them in the oven at 400 degrees for 15 to 20 minutes. The controlled heat produces a jammy and concentrated result without any plasma risk. For tips on storing fresh grapes, see our article on how to store berries.
3. Whole hot peppers Microwaving whole hot peppers releases capsaicin, the compound responsible for the burning sensation in spicy foods, into the air in the form of vapor. Capsaicin vaporizes at temperatures reached inside a microwave and the vapor remains trapped in the microwave cavity. When you open the door, the cloud releases directly towards your face. The effects are similar to those of exposure to pepper spray: intense eye irritation, coughing and throat burning that can last for hours. This is not a minor inconvenience. This is a real danger documented by many food safety experts and poison control resources.
⚠️ Ventilation is not enough
Opening a window does not adequately protect against the capsaicin vapors released by a microwave. The concentration released when you open the door is immediate and direct. If you need to reheat a dish containing whole peppers, use the cooker with lid and vent, or a conventional oven. If possible, remove whole peppers before microwaving them. This applies to jalapeños, serranos, habaneros and any other variety of whole pepper.
Safe alternative: Reheat dishes containing pepper on the stove over low heat, covered. OUR strawberry jalapeno salsa And jalapenos stuffed with chorizo are both best served chilled rather than reheated.
4. High-proof alcohol Heating high-proof alcohol in the microwave releases flammable vapors into the enclosed cavity. Microwaves can produce arcs (internal sparks) under certain conditions, and this spark in an enclosed, steam-filled space creates a fire hazard. This applies to spirits, fortified wines and any cocktail with a significant alcohol content. The risk is proportional to the evidence: low-alcohol beer or wine is unlikely to reach flammable vapor concentrations in typical reheating scenarios, but high-alcohol spirits and cocktails are another matter.
Safe alternative: Gently warm alcoholic beverages on the stove in a saucepan over the lowest heat, never above a simmer. This allows you to control the temperature and eliminates the risk of steam in a closed cavity.
5. Frozen meat (if not cooked immediately) The USDA Food Safety and Inspection Service explicitly warns that meat thawed in a microwave should be cooked immediately afterward. This is not a quality guideline. This is a food safety rule. When frozen meat is thawed in the microwave, the outer layers begin to warm and can reach temperatures in the bacterial danger zone (40 to 140 degrees Fahrenheit) while the interior is still partially frozen. If this meat remains at room temperature, even briefly, bacteria in the heated areas will multiply quickly. The interior also eventually reaches a thawing temperature, but by that time the outer layers may already have dangerous numbers of bacteria.
⚠️ The USDA rule
Meat defrosted in the microwave should go directly from the microwave into a hot pan or oven. No rest, no pre-preparing other ingredients, no setting aside while you chop vegetables. The USDA is unambiguous: Foods thawed in the microwave should be cooked immediately. For safe, risk-free thawing, thaw frozen meat in the refrigerator overnight or use the cold water method (sealed bag submerged in cold water, changed every 30 minutes).
6. Stuffed poultry The USDA specifically warns against cooking or reheating stuffed poultry in the microwave. The energy of the mi cro-waves penetrate down to about 1 to 1.5 inches, meaning that the center of a stuffed bird, the densest part of an already dense food, may never reach a safe temperature, even when the surface is read correctly. The stuffing insulates the interior cavity from heat, the bones further disrupt the heating, and the result is a dish whose exterior is hot and whose center can still harbor salmonella and other pathogens at temperatures that allow them to survive. This applies both to whole roasted poultry to be reheated and to raw stuffed poultry to be cooked.
Safe alternative: Reheat leftover turkey or chicken with stuffing in a conventional oven at 325 degrees Fahrenheit, covered with foil, until a thermometer inserted into the center of the stuffing reads 165 degrees Fahrenheit. For tips on storing leftover turkey and chicken, see our how long do leftovers last guide.
7. Non-microwave-safe plastics Not all plastics are microwave safe, and the distinction is important. Plastics that are not suitable for microwave use can soften, warp or melt at microwave temperatures, releasing chemicals including BPA (bisphenol A) and phthalates into food. The FDA has linked BPA exposure to concerns about hormonal disruptions. Yogurt containers, takeaway pots, margarine containers and single-use plastic bags are common examples of plastics that are not suitable for microwave use.
✅ How to tell if plastic is microwave safe
Look for the microwave safe symbol (a microwave icon or wavy lines) on the bottom of the container. If it is not there, do not use it in the microwave. Glass and ceramic containers are always the safest choice for reheating in the microwave. Never put plastic wrap in the microwave directly touching food. If you cover food with plastic wrap in the microwave, leave space so steam can escape and the wrap does not come into contact with the surface of the food.
8. Breast milk and infant formula The FDA explicitly warns against microwaving breast milk or infant formula. Microwaves heat liquids unevenly, creating hot spots in a bottle that may not be detectable from the outside. The bottle can be hot or even cold to the touch while containing pockets of liquid hot enough to burn a baby’s mouth and throat. This risk is well documented and the recommendation is universal among pediatric and food safety authorities.
Safe alternative: Place the bottle or sealed bag in a bowl of warm water for a few minutes, or run warm tap water over the bottle while swirling it. Both methods heat more evenly and safely. Shake or swirl the bottle and test a few drops on your wrist before feeding.
9. Shell shells Shellfish in their shells pose a risk of vapor trapping in the microwave. Clams, mussels, and oysters in the shell build pressure as their internal liquid heats, and the shells can burst with significant force, sending shell fragments and hot liquid inside the microwave. Even shellfish that don’t burst often come out rubbery and overcooked due to their high collagen content and the rapid, uneven heat of microwave cooking.
See also
Safe alternative: Steam the shellfish on the stove in a covered pot with a little water or wine. They open naturally and cook evenly in 5-7 minutes. For a dish that highlights the shellfish, our corn chowder with clams It is best prepared fresh and reheated gently on the stove.
10. Carrots and some root vegetables Carrots can arc in the microwave, which means producing visible sparks. This happens because carrots (and sometimes other root vegetables like beets and green beans) absorb minerals from the soil as they grow. These minerals, particularly iron, magnesium, and selenium, can interact with microwave energy and produce sparks similar to those that occur when metal is passed through a microwave. Sparks can damage the interior of the microwave and, in the worst case, start a fire.
✅ The exception: sliced or diced carrots
The risk of electric arcing is more associated with dense, intact parts. Thinly sliced or diced carrots in a dish with plenty of liquid (soup, stew) are much less likely to arc than large pieces heated alone. If you notice sparking with a vegetable, immediately turn off the microwave and remove the food. Do not use a microwave damaged by arcing until the interior has been inspected. For our carrot-ginger vinaigrettecarrots are used raw and do not require any heating.
11. Fried Foods Fried foods exist for their contrast: crispy exterior, tender interior. The microwave definitely destroys this contrast. The steam produced during microwave reheating saturates the breading or dough from the inside out, producing a soggy coating that cannot be restored by additional time in the microwave. The more time you spend in the microwave trying to crisp it up, the drier and tougher the inside becomes while the outside remains soft.
✅ The best method
Reheat fried foods in a dry skillet over medium heat (2 to 3 minutes per side), a 400-degree oven on a rack (8 to 10 minutes), or an air fryer (3 to 5 minutes at 375 degrees). Each of these methods removes moisture from the surface and restores at least some of the original crackle. The microwave cannot do this.
12. Processed meats Hot dogs, bacon, sausages and other similar processed meats present a problem specific to microwaves: the high fat and salt content creates uneven energy absorption, producing spots that reach very high temperatures while adjacent areas remain cold. This uneven heating creates the same food safety risk as any protein: bacteria survives in cold areas even though the surface appears fully cooked. Hot dogs in particular can arc (spark) in the microwave due to the uneven distribution of salts and additives in the housing. If you see sparks, turn off the microwave immediately. Processed meats are best cooked on a stovetop or under a grill where heat distribution is more controllable.
13. Whole fruits with intact skin Any small, whole fruit with a skin that is tight and retains moisture can create a steam trapping problem in the microwave. Cherry tomatoes, blueberries and small plums are the most common examples beyond grapes. The skin prevents steam from escaping, the pressure builds and the fruit bursts. The resulting explosion can be surprisingly powerful and spread hot liquid throughout the microwave. Pierce or slice any whole fruit before microwaving it if you need to reheat it.
14. Tomato sauce (uncovered) Tomato sauce will not create a safety hazard in the microwave, but it will create a mess which is a significant quality issue. The thick consistency of tomato sauce traps steam until it bursts through the surface forming a splatter pattern that coats the entire interior of the microwave. Each bubble that forms beneath the surface releases with more force than expected. Beyond the mess, tomato sauce burns in the microwave in a way it doesn’t on the stovetop, because direct contact with the bottom of the container overheats the sauce before distributing the heat evenly.
Safe alternative: Reheat tomato sauce in a saucepan on the stove over low to medium heat, stirring occasionally. If you must use the microwave, cover tightly with a vented lid or plastic wrap that doesn’t touch the sauce, and use medium power in short bursts, stirring between each. See our tortilla soup And strawberry jalapeno salsa for tomato dishes that reheat best on the stovetop.
15. Water (under certain conditions) Plain water can overheat in a very clean microwave container without nucleation points (scratches, impurities, or residue). Superheated water reaches boiling temperature without actually boiling because there is no point for bubbles to form. When the container is then disturbed (picked up, stirred, or a spoon dropped into it), the water bursts violently, sending boiling water outward. This is a documented phenomenon with proven burns, but which requires special conditions (very smooth container, pure water, prolonged heating) that are not common in daily use. The risk is real enough that the FDA has issued guidance on it.
✅ How to prevent it
Place a wooden chopstick, non-metallic stirrer, or wooden skewer in the water before microwaving. These provide nucleation points that allow bubbles to form normally. Or simply heat water in a kettle rather than a microwave for any application where you need to boil water reliably and safely.
16. Metal and aluminum sheet Metal should never be microwaved. This includes foil, metal ties, plates and bowls with gold or silver edges, stainless steel travel mugs, and any container with metal handles or decorative metal edges. When metal is exposed to microwave radiation, it reflects the energy instead of absorbing it, causing reflected waves to build up and produce arcs, the same visible sparks that occur with mineral-rich cores. With metal, the arc is more intense, more sustained, and more likely to damage the microwave’s interior, start a fire, or cause the magnetron (the component that generates the microwave energy) to fail.
⚠️ The risk of the Twist Tie
Small metal objects are often more dangerous than large ones in a microwave because their small size creates a higher concentration of reflected energy. A single metal twist tie from a bread bag can produce enough arc to char the inside of your microwave in seconds. Always check containers and bags for any metal items before microwaving. This includes takeout containers with metal handles, Chinese food containers with wire handles, and any bag sealed with a metal core tie.
Safe alternatives: Use glass or ceramic containers microwave safe. If you must cover food, use a microwave-safe lid, paper towel, or microwave-safe plastic wrap away from the surface of the food.
Foods People Think Can’t Be Microwaved, But They Can Food The myth The reality Bread Makes him dangerous Safe but quickly becomes stale and rubbery. 10 to 15 seconds only. Raw potatoes Will explode Safe if pierced first. Always pierce with a fork before microwaving. Scrambled eggs Will explode like shell eggs Safe when beaten first. It is the shell that is the danger, not the egg itself. Fish fillets Dangerous or smelly Microwave safe. Smelly if overcooked. Use medium power and short bursts. Leftover meat Always dangerous Safe if stirred halfway and checked at 165°F throughout with a thermometer. Frequently Asked Questions Why do eggs explode in the microwave?
Eggs in the shell explode in the microwave because the shell cannot vent the steam produced when the internal liquid heats quickly. The pressure builds until the hull fails. Hard-boiled eggs may also explode when reheated, as residual moisture in the yolk overheats and vaporizes when the egg is bitten or cut. Always remove eggs from the shell and slice or chop them before reheating in the microwave. For complete advice on egg storage, see do eggs go bad.
Why do grapes fizz in the microwave?
Grapes create plasma in the microwave due to their size, spherical shape, and water content. Microwave energy concentrates at the point where two grape halves touch, creating electromagnetic hot spots that ionize the surrounding air into plasma, producing visible sparks. This was documented in a 2019 paper published in PNAS (Proceedings of the National Academy of Sciences). The same phenomenon can occur with other small, spherical foods with high moisture, including cherry tomatoes and blueberries.
Is it safe to put plastic containers in the microwave?
Only if they are labeled microwave safe. Plastics without this label may soften, warp, or leach chemicals, including BPA, into food when heated. Yogurt pots, takeout containers, margarine tubs, and single-use plastic bags are all common examples of plastics that aren’t microwave safe. Glass and ceramic are always the safest choices for reheating in the microwave.
Can you microwave hot peppers?
Whole hot peppers should not be microwaved. Heating releases capsaicin vapor that gets trapped in the microwave cavity and travels toward your face when you open the door. The effect is similar to that of pepper spray: intense irritation of the eyes, coughing and burning sensation in the throat. If you must reheat a dish containing peppers, remove the whole peppers first or reheat them on the stovetop with ventilation.
Can you reheat fried chicken in the microwave?
It’s possible, but the result will be disappointing. Steam from the microwave saturates the breading from the inside, making it permanently soggy. No additional time in the microwave will restore the crust. For crispy, reheated fried chicken, use a dry skillet over medium heat, a rack in a 400 degree oven, or an air fryer at 375 degrees. All three methods remove surface moisture instead of adding it.
Why does the microwave heat food unevenly?
Microwaves penetrate food to a depth of only 1 to 1.5 inches, according to the USDA FSIS. Beyond that, the heat must travel inwards by conduction, as in a conventional oven, but much more slowly because microwave cooking times are short. Dense foods, thick cuts, and foods with uneven geometry all develop hot spots on the surface and cold spots in the center. Stirring halfway through reheating, rotating the container, and using medium power rather than full power reduce but do not eliminate this uneven heating.
Is it safe to cook frozen meat in the microwave?
Only if you cook it immediately afterwards. The USDA Food Safety and Inspection Service states that meat thawed in the microwave should be cooked immediately because the outer layers enter the bacterial danger zone (40 to 140 degrees Fahrenheit) during thawing. If you walk away and let thawed meat sit in the microwave before cooking, the warmed outer layers become an environment for bacterial growth. For safe defrosting without time constraints, use the refrigerator overnight or the cold water method.
Can you microwave breast milk?
No. The FDA recommends against microwaving breast milk or formula. Microwaves heat liquids unevenly, creating hot spots inside the bottle that can burn a baby’s mouth and throat even when the bottle is hot on the outside. Warm breast milk and formula by placing the sealed bottle in a bowl of warm water for a few minutes, or run warm tap water over the bottle while swirling it.
Why do carrots fizz in the microwave?
Carrots absorb minerals from the soil, including iron, magnesium and selenium. These minerals interact with microwave energy and can produce electrical arcs, the same sparking phenomenon that occurs when metal is microwaved. If you see sparks when microwaving carrots or other root vegetables, turn off the microwave immediately and remove the food. Thin slices in a liquid-based dish are much less likely to form than large, intact pieces.
Can you put alcohol in the microwave?
You should not put high proof alcohol in the microwave. Heating high-ABV spirits and cocktails in a microwave releases flammable vapors into the enclosed cavity. Microwaves can produce stray sparks under certain conditions, and ignition in a steam-filled cavity is a real risk. Instead, gently reheat alcoholic beverages on the stove in a saucepan over low heat.
What temperature should food reheated in the microwave reach?
Any reheated leftovers should reach 165 degrees Fahrenheit, measured with a food thermometer, according to the USDA FSIS. For soups and sauces, bring to a boil. In the microwave specifically, stir or rotate foods halfway through cooking to reduce cold spots, then let the food sit for 2 minutes before checking the temperature: heat continues to distribute during the resting time. See our how long do leftovers last guide for comprehensive safety tips.
Can you put metal in the microwave?
No. The metal reflects microwave energy instead of absorbing it, causing arcing (sparking) that can damage the interior of the microwave, start a fire, or destroy the magnetron. This applies to foil, metal ties, gold or silver rimmed dishes, stainless steel containers, and any takeout container with metal handles. Small metal objects like twist ties are particularly dangerous because they concentrate reflected energy in a small area. Always use glass or ceramic containers for reheating in the microwave.
Is it safe to microwave food in styrofoam?
Most Styrofoam (Styrofoam) containers are not microwave safe. At microwave temperatures, Styrofoam can soften and leach styrene, a suspected carcinogen, from food. Only polystyrene containers specifically labeled microwave safe have been tested and rated for this use. If in doubt, transfer food to a glass or ceramic container before microwaving.
Further reading
23 Foods You Should Never Refrigerate 20 Foods You Should Never Freeze 15 Foods That Go Bad Faster Than You Think How long do leftovers last? Can expired condiments make you sick? Do eggs go bad? Does rice go bad? Complete Food Storage Guide: 120+ Foods Better Living may earn commissions through affiliate links and may occasionally offer sponsored or partnered content. If you make a purchase through our links, we may receive a small commission at no cost to you.