Woman heating food with microwave machine

5 things you should never heat in the microwave if you want to protect your health

There are a number of materials and products that we should never put in the microwave, but we are not always clear about the dangers posed by some of them

The microwave is a very common electronic appliance, capable of heating all kinds of food and beverages in a very short time. Thanks to this, we save a lot of time and the process is much simpler than if we use other alternatives. However, we must be careful with what we put inside, because microwaves are very powerful and using them with something inappropriate could have very negative consequences.

To begin with, we could put our health at risk, making the food so bad that it could even make us sick. Another danger is the possibility of causing some kind of explosion or short circuit, and end up spreading a fire in the home, with all that this implies both for the physical integrity of those who live in it and for the material goods.

Therefore, keep in mind that you should never put any of the following five things in the microwave.


Let’s start with one of the most basic materials that should never be put in the microwave. Plastic melts inside a working microwave, and if it is a container made of this material, it could seriously contaminate the food inside and that we are going to consume next.

The bags in which we put food, yogurt containers or many plastic tuppers (unless otherwise indicated) are some examples of this. But there are exceptions: especially in the case of tuppers, you will find a large number of them that, despite being made of plastic, include an indication that they are suitable for microwaving. Make sure you find this sign before putting it inside.

Metal tools

As metal is by nature a conductor of electricity, it is not capable of absorbing the electromagnetic waves of the microwave, and can easily damage the appliance and even cause a fire.

Metal is not able to absorb electromagnetic waves from microwaves.

You probably already know that metal utensils such as forks, knives and spoons should not be used. But you should also be careful with certain glasses, pots and pans, among others, which sometimes have metal parts. In addition, many cups are made of stainless steel and are also unsuitable, so make sure that they are before heating coffee with them in the micro.

Aluminum Foil

Aluminum foil, which is so useful for preserving food and many other things, also has its dangers. After all, it is made of metal, so it presents the same risks as the aforementioned metal utensils.

The electric fields of microwaves cause very dangerous sparks in the aluminum foil, since they produce a phenomenon of accumulation of charges in different areas of the foil. Putting this material in the appliance is one of the most common mistakes that can cause an explosion.

Polystyrene foam

Styrofoam is a very common material used in take-away or delivery food services, for example in hamburgers and caf├ęs. Many people are unaware of the risks of contact with microwaves, and the day after buying such food, they put the leftovers in to heat them up.

Many take-away food containers are made of polystyrene foam.

This is a very serious mistake, as polystyrene releases chemicals that are very harmful to your health and can even cause cancer. The best thing to do is to throw these containers away, and heat the leftover food in a normal plate or in any other container that you have checked that it is suitable.

Cardboard and paper

Something similar to the above occurs with cardboard or paper boxes and containers, which are also very common in takeaway or home delivery food, for example in pizzas. In this case, what is really dangerous is that many cardboard boxes come with slightly metallic or plasticized parts, which imply the risks we already know. And although most of the cartons can be used in microwaves, just in case and to avoid problems, it is best to avoid putting them in this appliance, unless they clearly indicate that they are suitable.