The use of microwaves has become mandatory in modern kitchens. They’re fast, convenient, and great for warming up leftovers in just minutes. But while microwaves can be a lifesaver on busy days, not all foods are friendly to the microwave.
Reheating some foods in the microwave can, in fact, ruin their texture, strip them of nutrients, or form harmful compounds that can feel like a health risk.
Ever wonder why leftover chicken turns rubbery when you microwave it? Or how fried food turns into a soggy mess? It’s not just a matter of texture—certain foods can even turn unsafe to eat if they’re reheated the wrong way.
So before you throw that plate in the microwave, take a few moments to learn about 12 foods you should never reheat in the microwave—and the proper way to warm them up.
How Microwaves Work (And Why Some Foods React Badly)
Microwaves cook food with electromagnetic waves that stimulate water molecules, causing them to vibrate and produce heat.
This method does heat food rapidly but not super evenly, resulting in some spots being steaming hot and others cold, which could lead to dangerous bacteria growth.
Moreover, specific foods contain complex proteins and chemical compounds that transform when cooked again, resulting in nutrient loss, texture problems, or the production of toxic substances.
To help keep your food safe, nutritious, and delicious, let’s run through the 12 foods you should absolutely avoid reheating in the microwave—and what to do instead.
1. Chicken: Breeding Ground for Bacteria and Rubber-Like Texture
Chicken is one of the riskiest foods to microwave reheat.
🔴 The problem? Uneven heating. Some areas heat fast while other parts linger in the bacteria danger zone (40°F – 140°F), where harmful bacteria like Salmonella and Campylobacter can grow.
Also, chicken’s protein structure changes upon reheating, making it rubbery, tough, and difficult to digest.
✅ Safe Reheating Method:
- Oven: Reheat chicken in the oven at 350°F (175°C) for 10-15 minutes or until warmed.
- Stovetop: Reheat with a splash of broth or water over medium-low heat to keep moisture.
2. Rice: A Hidden Threat of Bacteria
While rice might seem innocuous, it is one of the most common sources of food poisoning.
Bacteria called Bacillus cereus, which are present in rice, produce heat-stable toxins. Those toxins can multiply if rice sits out too long, and microwaving won’t kill them.
✅ Safe Reheating Method:
- Stovetop: Add a few tablespoons of water and heat, stirring until warmed through.
- Oven: Bake at 300°F (150°C) for 15 minutes, covered with foil to stop it from drying out.
3. Potatoes: A Botulism Risk
Cooked potatoes, particularly when wrapped in aluminum foil, can be host to Clostridium botulinum bacteria, the germ that causes botulism, a severe and often deadly form of food poisoning.
Microwaving won’t kill off these bacteria, which can be even worse if the reheating is done improperly.
✅ Safe Reheating Method:
- Oven: Bake at 350°F (175°C) for 15 minutes to revive texture and kill bacteria.
- Stovetop: Sauté in a bit of butter or oil for ultra-crispy, golden-brown potatoes.
4. Mushrooms: Nutrient Loss & Digestive Concerns
Mushrooms are high in protein and other compounds that break down easily when cooked again.
Microwaving changes their protein structure, which can cause digestive issues as well as nutrient loss.
✅ Safe Reheating Method:
- Stovetop: Gently heat mushrooms with a touch of butter over low heat for the best flavor and texture.
5. Eggs: A Possible Explosion Hazard
Reheating eggs—especially hard-boiled ones—is a recipe for disaster.
When cooked in a microwave, eggs can generate steam inside the shell or membrane, and we know what happens then: the egg erupts suddenly, causing burns and a big mess.
Scrambled eggs can become rubbery and unappetizing too.
✅ Safe Reheating Method:
- Stovetop: Heat eggs on low, stirring often.
- Eat Cold: Enjoy hard-boiled eggs cold or at room temperature.
6. Breast Milk: Destroy Nutrients and Cause Hot Spots
Microwaving breast milk destroys critical antibodies and nutrients, so it does not provide such benefits to babies.
Even worse, microwaves heat milk unevenly, forming hot spots that could burn a baby’s mouth.
✅ Safe Reheating Method:
- Warm Water Bath: Submerge the bottle in a bowl of warm water or use a bottle warmer.
7. Seafood: The Smell and Bacteria Overpower
Microwaving seafood makes it smell way too strong and messes up its delicate texture.
Uneven heating can leave cold spots, raising the risk of bacteria growth.
✅ Safe Reheating Method:
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- Oven: 275°F (135°C) for 10 minutes.
- Stovetop: Rewarm slowly with butter over low heat.
8. Processed Meats: Chemical Reactions That Are Harmful
Microwaving processed meats, such as hot dogs, bacon, and sausage, can make the preservatives (nitrates and nitrites) turn into carcinogenic nitrosamines, which are connected with cancer.
✅ Safe Reheating Method:
- Oven or Skillet: Heat processed meats in the oven at 325°F (165°C) or on the stovetop.
9. Leafy Greens: Nitrate Conversion Risks
Nitrates in spinach, kale, celery, and other leafy greens can turn into nitrosamines (which is a possible carcinogen) if reheated at high temperatures.
✅ Safe Reheating Method:
- Eat Cold: Stir leftovers into salads or blend into smoothies.
- Steam Lightly: Steam to reheat, using low-heat methods.
10. Cooking Oils: Smoke Points + Toxins
Oils, such as olive oil, flaxseed oil, and grapeseed oil, should not be microwaved, as they heat too fast, reaching their smoke points and causing the release of toxic compounds.
✅ Safe Reheating Method:
- Stovetop: Heat oils in a low-temperature layer.
11. Takeout Containers: Hidden Chemicals
Many takeout containers—especially plastic ones—are not microwave-safe.
Microwaving food in these containers may cause leaching of harmful chemicals such as BPA, which can increase health risks.
✅ Safe Reheating Method:
- Always transfer food to a microwave-safe glass or ceramic dish before reheating.
12. Fried Foods: Becomes Soggy Instead of Crispy
Fried foods turn into a greasy, soggy mess in the microwave.
✅ Safe Reheating Method:
- Air Fryer or Oven: Reheat at 375°F (190°C) for 5 to 10 minutes until crispy again.
Word of Caution: Microwave with Care!
Microwaves are extremely convenient — but they’re not always the best vehicle for food reheating. Some foods, such as chicken, rice and processed meats, can turn unsafe, while others, such as eggs and seafood, lose their texture and nutrients.
So the next time you consider reaching for the microwave, think twice, and opt for one of these safer reheating methods to keep your meals tasty and nutritious!
FAQs:
Why can it be dangerous to reheat food in the microwave sometimes?
Microwaves heat food unevenly, creating cold spots where bacteria such as Salmonella and E. coli can survive. Some foods also change in chemical constituency at high microwave heat that makes them toxic, less nutritious or undesirable in texture.
Are there some foods that should never be reheated in the microwave?
Things you shouldn’t microwave include:
- Chicken (uneven cooking, risk of bacterial contamination)
- Rice (Bacillus cereus bacteria potential)
- Potatoes (risk of botulism)
- Mushrooms (degradation of proteins)
- Eggs (explosion risk, rubbery texture)
- Breast milk (loss of nutrients, uneven heating)
- Seafood (displeasant texture, strong odors)
- Processed meats (formation of malignant chemicals)
- Green-leaved vegetables (for the conversion of nitrates into carcinogens)
- Cooking fats (breakdown of toxic substances)
- Food in takeout containers (possible leaching of chemicals into food)
Specific Food Concerns
What happens when you microwave-reheat chicken?
When you reheat chicken in a microwave, for instance, it breaks down protein structure in a different way than normal cooking does, which can lead to rubbery, chewy meat. Also, uneven heating can allow bacteria to survive if the chicken doesn’t get reheated all the way to 165°F (74°C).
Can reheating rice actually make you sick?
Yes! Properly storing rice is critical because rice can harbor Bacillus cereus, a bacteria that forms heat-resistant spores. Left out at room temperature too long, cooked rice can become a breeding ground for bacteria, which produces toxins that aren’t killed when the rice is microwaved. Store rice in the fridge within an hour then reheat to 165°F (74°C).
Are potatoes dangerous to reheat?
Cooked potatoes held at room temperature for extended periods can also grow Clostridium botulinum, a bacteria that creates a dangerous toxin. Nervous system symptoms of botulism include dizziness, slurred speech, and difficulty swallowing. Microwaving does not kill these toxins, so botulism poisoning can occur even from improperly stored potatoes after reheating.
Toxic ‘Mushrooms’ Reheated: Is That Possible?
Mushrooms have disappearing proteins that can create problems in your stomach if the mushrooms are reheated incorrectly. If mushrooms are stored properly, gently reheating on the stovetop is better than zapping them in a microwave.
What happens if you microwave eggs?
Eggs can explode in the microwave, whether in whole form or cooked into scrambled eggs, as steam will build up inside and sometimes cause explosions in the microwave or in your mouth when you take a bite. Also, eggs in the microwave acquire a rubbery, unpalatable texture.
Is heating breast milk in the microwave bad?
Yes! Microwaving breast milk also destroys valuable nutrients and antibodies that are essential for a baby’s well-being. Moreover, microwaves cause uneven heating, which can create hot spots that burn a baby’s mouth. Do not warm breast milk in a microwave — instead place the bottle in warm water.
The science behind seafood getting super stinky in the microwave?
Microwaving seafood again causes the proteins to break down, resulting in a fishy smell and rubbery texture. The most effective way to reheat seafood is in a pan set over low heat or in the oven at a low temperature.
So what’s the issue with reheating processed meats?
Processed meats (such as bacon, sausage and hot dogs) have preservatives known as nitrates and nitrites. When heated in a microwave, these chemicals can create nitrosamines — compounds tied to cancer. It’s safest to reheat processed meats in a skillet or oven.
I should not reheat leafy greens in the microwave?
Natural nitrates are found in leafy greens, such as spinach, celery, and kale. Under high microwave heat, nitrates can get converted into nitrosamines with carcinogenic (cancer-causing) properties. Leafy greens are best eaten fresh or lightly steamed.
Are cooking oil types toxic if they’re microwaved?
Yes! Oils such as olive oil and flaxseed oil can get to their smoke point in a microwave very quickly, producing toxic fumes and free radicals that are dangerous to your health. When stovetop heating oils, always do so gently.
How safe is it to microwave takeout containers?
Just about any plastic and Styrofoam takeout containers aren’t microwave-safe, and they can leach harmful compounds like BPA and phthalates into your food. Always transfer food to a glass or ceramic dish safe for microwave use before reheating.
Safe Reheating Methods
To reheat food for best results, use these approaches:
- Stovetop: Ideal for meats, rice, vegetables and pasta.
- Oven: Good for casseroles, potatoes and baked things.
- Double Boiler (Water Bath): Perfect for delicate sauces and dairy items.
What’s the safest way to make sure my food is reheated correctly?
Always reheat food to 165°F (74°C) by using a food thermometer to prevent foodborne illnesses. Refrigerate leftovers and stir the food halfway through reheating it, to kill any cold spots bacteria can survive in.
Final Thoughts
Microwaving is a fast, handy option for reheating leftovers, but not all food items can withstand the high heat generated by a microwave without becoming unsafe for consumption. Microwaving certain foods destroys their nutrients, generates harmful toxins, or presents food safety hazards.
Knowing which foods not to microwave—and using healthier reheating methods—will keep your meals safe, delicious and nutritious. The next time you’re about to put something in the microwave, consider: Is there a better way to reheat this? Your health and palate will thank you!
