Can You Put Plastic Bag in Microwave?

I often use plastic bags from the grocery store for storing and carrying food.

When I am lazy, I throw the bag along with the food in the microwave to quickly reheat the food. It is a common event in my everyday life. 

However, with the recent concerns about plastics and leeching, I wonder if plastics are safe to be used for heating or cooking. Is it safe to put a plastic bag in the microwave?

Can You Put a Plastic Bag in the Microwave? 

To be on the safe side, regardless of the chemical composition of the plastic bag, I would not recommend you put it in the microwave

The reason is that it can leach harmful chemicals into your food.

Allow me to elaborate. 

Why You Should Not Use a Plastic Bag in the Microwave 

According to research, BPA and phthalates are harmful chemicals, and both are added to plastic to make it durable and flexible. 

Both phthalates and BPA have been linked to disrupting the body’s hormones, causing diabetes, cardiometabolic disorders, and obesity.

Phthalates, as well as BPA, have been found to leach into food when the plastic is microwaved.  

Nowadays, there is a trend of removing BPA and making Plastic BPA free.

These plastics are then considered safe.

However, according to research, even BPA-free plastics can release chemicals that cause hormone disruptions when microwaved.  Some of the chemicals are phthalates, bisphenol F, bisphenol S, etc.

In some cases, BPA-free products were found to release chemicals having more estrogenic activity ( hormonal disruption activity) than plastics containing BPA.

So I would urge you to completely steer clear unless the plastic is specifically labeled microwave safe and meets the strict FDA standards like Ziploc bags

Also read: How To Avoid Microplastics In Food?

Can Ziploc Bags be Microwaved? 

According to the company,

“all microwavable Ziploc bags meet the safety requirement of the Food and Drug Administration (FDA) for temperature associated with defrosting and reheating food in microwave ovens” 

Another chemical that was released while heating plastic was found to be dioxin. All Ziploc brand products are 100% dioxin free.

Also read: Can You Put Plastic in the Oven?

Understanding Plastic and the Long-Term Effects

Not all plastics are harmful. But in general, it is best to avoid using plastic over a long time.

This is because plastic is not one chemical. It contains a lot of additives like plasticizers, colorants,  and antioxidants. These may be safe for short-term exposure, but it is best to avoid chemical exposure in the long run. 

Just like plastics, human bodies also react differently to different chemicals. Long-term exposure should be avoided if possible. 

Whatever chemical gets released, some sort of leaching will occur at high temperatures. Ingestion of chemicals is a health safety concern.

A study was done with a group of 20 participants. They were given a few days of fresh food and a few days of canned food and food packed in plastic.

When their urine samples were collected, it was found that urine levels of BPA and DEHP metabolites decreased to a great extent when participants’ food was restricted to food with limited packaging.  

Also read: Can You Microwave Paper Plates?

How to Use Microwave Safe Plastics 

Here are a few tips that will give you additional safety, when you use microwave-friendly plastic bags

Open an Inch 

When you use a microwave-safe plastic bag like Ziploc, make sure to open an inch to allow steam to escape when the contents get heated up. 

This will release steam pressure and prevent the bag from bursting.

Place a Dish Underneath 

Use a microwave-friendly dish or bowl beneath the bag. This will prevent any dripping or leaking of the food from the plastic bag. 

Do Not Heat for Long 

It is a good idea to avoid overheating the plastic bag. Heat at low to medium temperatures for a short duration. Do not cook for long durations as overheating will cause leaching. 

Ziploc bags are for defrosting or reheating but do not cook food in a Ziploc bag inside the microwave. 

Wear Gloves/Mitts to Remove the Bag from the Microwave 

Once the bag is heated, it will be hot to the touch. You have to be careful and wear oven mitts before removing the plastic from the microwave. 

Keep an Eye 

While heating food in a microwave-safe bag, make sure to be around to keep an eye on the integrity of the bag.

It is not a good idea to leave the bag unattended for too long inside the microwave. 

Also read: Why Do Hot Dogs Spark in the Microwave?

Alternatives to Using a Plastic Bag in the Microwave

It is better to use a plastic bag sparingly inside the microwave. Here are some alternatives you can try : 

  • Use a microwave-safe glass bowl/dish or a plate 
  • Use microwave-safe oven bags 
  • Using microwave-friendly cookware to cover/ store, and reheat the food
  • Using parchment paper or wax paper to cover the food in the microwave

Dangers While Using Plastic Bag Inside the Microwave

If you choose to heat microwave-friendly bags like Ziploc, there are a few things you need to be careful about :  

  • If your microwave-safe plastic bag looks worn out, damaged, or scratched, do not use it inside the microwave as there are high chances of chemical leaching 
  • Do not overfill your bag. The food inside can expand and build up steam. This can cause pressure on the plastic bag, and it can tear, leak, or even burst.  
  • Plastic tends to melt at high temperatures. Microwave-safe bags usually don’t melt at normal heating temperatures of the microwave. However, leaving them exposed to hot temperatures for a long time inside the microwave can cause them to go soft and even melt. 
  • Never put liquids or water inside the plastic in the microwave. Once the water reaches boiling point, the bag will start to melt. Due to the same reason, you should not submerge a plastic bag in boiling water. 
  • The heated bags should not be touched with bare hands or fingers as they can burn your skin. Also, if you forget to vent the bag before placing it inside the microwave, the steam will be choked up inside. As soon as you open the bag, hot steam will get released that can cause burns.

To sum up, do not use a worn out or damaged plastic bag, do not overfill the bag with food, don’t heat the bag for a long duration, don’t boil liquids inside the plastic bag, and don’t forget to open the bag a little to allow steam to vent out.  

Avoid the above possible scenarios, and you will stay safe.

Also read: Why Do Glass Plate Break in the Microwave?

Final Words 

It is best to avoid using a plastic bag inside the microwave.

This is because of the chemical leaching, which has been observed to disrupt the hormones of the body, causing cardiometabolic disorders, diabetes, and obesity. 

I have mentioned the links to the studies and research done above. You can read more details in the link sources.

Even if some plastic is labeled as BPA-free, it was found to release chemicals that disrupt the hormones inside the body. 

The only way to use plastic inside the microwave is that it should meet the strict FDA requirements and should be labeled microwave safe like Ziploc bags. I have mentioned tips for using microwave-safe plastics inside the microwave. 

I have also written about alternatives and avoidable dangers while using plastic bags inside the microwave.

I hope you find all the information above useful and stay healthy and wise. All the best! 

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I’m Jueria and I am a regular contributor on In my articles, I share time-saving techniques, appliance wizardry, and health-friendly recipes to bring taste and wellness to your table. So raise a glass (or a spatula) with me, to good health and good food, made easy!