Why Can’t You Microwave Starbucks Cups?

Why Can’t You Microwave Starbucks Cups?
Avoid microwaving Starbucks cups of coffee.

What do you do when your Starbucks coffee runs cold as you attend to other activities? Did you know you cannot microwave Starbucks cups? Read on to find out why…

It is common to take your cup of Joe as you run your errands. In the process of doing so, your coffee may run cold. In such cases, when the only heating element is a microwave, what should you do? Take cold , tasteless coffee or risk microwaving the cups, which have indicated, “Do not microwave”? No matter how bad it gets, do not microwave Starbucks cups unless they have indicated that it is safe.

Why can’t you microwave Starbucks cups? It all comes down to the fact that Starbucks cups are made of a material that can withstand the high temperatures of coffee but not that of active heating. For starters, the cups are lined with a blend of plastic and wax that holds them together. When these materials are exposed to extreme heat, they may melt and fall apart. You can already guess that it will be a hazard in your kitchen.

This article will look into reasons why you should not microwave Starbucks cups, alternatives available, how to determine if your dishes are microwave-safe, and other related issues. And check out our best travel mugs for coffee for a sustainable solution.

Why You Shouldn’t Microwave Starbucks Cups of Coffee

You might have already noticed that some Starbucks cups have indicated, ‘Do not microwave’. This care label is mostly found towards the bottom on the outer edge of the cup. We have looked at some of the reasons why you cannot microwave Starbucks cups as discussed below. However, note that not all Starbucks cannot be microwaved, as some are built to be microwave-safe.

The Material Of Starbucks Cups

Starbucks cups that cannot be microwaved are made of paper, which is coated with plastic to make it waterproof so that it does not leak. That is part of the reason Starbucks cupsand other paper cups are not recyclable.

Now, unlike solid containers, which are good for reheating food, paper is not. If anything, when exposed to extreme heating like that of the microwave, it tends to fall apart.

We talked more about why you can’t microwave paper coffee cups here.

Starbucks disposable paper cups
Starbucks paper cups cannot be microwaved.

Toxic Leeching

As mentioned before, Starbucks cups are held together by wax or glue. When these materials are exposed to direct heat, they may melt and leak into your beverage that you will end up consuming.

Consuming this beverage means introducing a certain level of toxins into your body. Although the effect of these toxins is long-term, it is dire to your health. As such, it should be avoided.

Check out our guide on how to heat up coffee without a microwave.


Alternatively, if the glue melts, your cup may start leaking from the sides.

Weird Taste

Should you manage to microwave your Starbucks cup, the part with the coffee may not remain intact. The problem comes in the upper part of the cup that does not have coffee.

If it burns, it will alter the taste of your coffee, and you do not want that, right?


Starbucks crew with cups of their products
Starbucks crew educate customers.

You might have heard of people who have got away with microwaving Starbucks cups. This shows that there is a slight possibility that you can microwave Starbucks cups. However, that is done with the knowledge that the manufacturers do not recommend.

This is because if someone microwaves the cups and gets burnt or injured, they can sue Starbucks for failing to give a warning.

As such, the warning of “do not microwave” is a corporate liability.

So, What Alternatives Do You Have?

Now that it is very clear you cannot microwave Starbucks cups, what should you do if you need to reheat your cup of coffee?

How you reheat your coffee depends on where you are and the heating elements near you. For instance, if you are at home, place your coffee in a saucepan and warm it under a stove. This is the best-recommended method since you can control the temperature of the coffee.

Alternatively, if you have a microwave, you can pour the coffee into a cup that is not made of paper or metal. Glass, ceramic , or Styrofoam cups would do a good job.

Which Starbucks Cups Can You Microwave?

Other than plastic cups, Starbucks sells other types of reusable cups. For cups that can be placed in the microwave, the company sells ceramic and glass cups.

Ceramic Starbuck Cups
Starbucks sells other reusable cups, such as ceramic and glass cups.

As such, if you insist on using Starbucks cups that can be tossed in the microwave, go for cups made of these two materials. That said, be careful when microwaving thin ceramic cups. These cups can become too hot , and you may end up burning your lips when you take coffee.

Apart from microwave-friendly cups, Starbucks also sells plastic tumblers. These tumblers are built reusable. Therefore, if you tend to forget your coffee mug, you can use the plastic cups.

Using reusable coffee cups reduces the ecological footprint of plastic waste from other paper cups. Note that the idea of recycling paper cups has yet to be embraced by many bodes. This is because it requires top-notch technology to separate the plastic from the paper.

How To Tell If A Cup Is Microwave Safe

The easiest way to tell if your cup , or any other dish for that matter, is microwave-safe is by checking care instructions.

Depending on the item you are using, the instructions are usually found on the cup. For instance, for Starbucks cups, the instruction is found near the bottom.

If the cup can be placed in a microwave, it will read, “Microwave friendly.” If not, the label may read, “Do not place in a microwave” or any other relevant information.

If the cup does not have a care instructions label, make efforts to contact the manufacturer through their website.

Other than the care label, there is an amateur way to determine if your cup is microwave-safe. Place a cup of water in the microwave. Let the microwave heat up. If, in the end, the cup remains cool and the water is heated up, the cup is microwave-safe.

Frequently Asked Questions

Does reheating coffee make it taste odd?

Most people argue that reheating your coffee is pointless especially since it changes its taste. The thing is coffee is only fresh within the first 30 to 60 minutes after brewing. So after it has cooled down flavor from the coffee tends to evaporate.
You would think that reheating your brew would make things better but no, when you warm your coffee the flavor is lost even more. This means that if when reheating your coffee you let it boil, in the end, you will take a poor cup of coffee in terms of flavor.
However, if your concern is the caffeine effect, do not worry, the caffeine remains intact whether you re-warm or re-boil your coffee.
That said, for the best experience for your brew, take your coffee when it is still hot and fresh. Also, should your coffee run cold and you can afford to buy another cup, then go for it.

How long should my brewed coffee stand?

Well as we have said above, take your coffee when it still hot, rather within the first one hour after brewing. That said the maximum number of hours that you can let your coffee stand is 12 hours. Past the 12 hours, drinking the coffee becomes a health risk.
Once the coffee has been left for the past 12 hours, it becomes a breeding ground for bacteria. As such, should you consume this coffee; you will be introducing bacteria to your system and posing health risks. In addition, since the coffee has cooled down to room temperature it provides a good ground for the bacteria to multiply
Other than bacteria growing, within the 12 hours, the coffee usually has collected dust and other specks found in the air. Imagine how much dirt you end up consuming in the name of coffee.
Therefore, you should not drink coffee that has been standing past 12 hours. Also, when you leave your coffee make sure you place a lid on it.
If you had drunk the coffee or even your lips had touched the coffee, then it is recommended that you do not leave the drink, finish up. When tasting the coffee you introduce bacteria found in your mouth and body to the coffee cup.
So should you leave the coffee, different bacteria will grow on it.

See Also:

How To Make Coffee Wit A Microwave? (It Works)

Starbucks Coffee Vs Kirkland Coffee

Best Starbucks Coffee



  • Aisling O'Connor

    Aisling is an Irish food and drinks writer and journalist fueled by coffee and herbal tea. She followed up her journalism degree with nutrition studies. Find Aisling on LinkedIn.