Is Reheating Coffee Bad For You? Read This First!

A close up of a coffee cup

This may come as a surprise to you, but not everyone drinks their coffee fast. Or perhaps it's not a surprise. Maybe you're one of the thousands of people who takes your time sipping your coffee, and maybe even reheating it. I know a lot of people who drink their coffee very slowly, and end up reheating it several times throughout the day. But it made me wonder if that's safe. So, of course, I had to dig to find this answer.

So, what's the verdict? Is reheating coffee bad for you? No. Reheating coffee is not bad for you. Depending on the brewing method, your reheating method, and any additives in your coffee, you will change the taste. However, there are no bad health effects of reheating your coffee.

I'll admit; I do reheat my coffee from time to time. So, I was pretty happy to find that answer. I still had a lot of questions though. If you still have questions too, keep reading! I'll dig deeper into the answer, plus give you some tips on safely reheating your coffee without making it taste awful.

Is reheating coffee bad for you?

Most assuredly not. Reheating coffee doesn't do much other than change the flavor of your coffee. For better or worse, it's all about the taste, not the danger. Unless of course you count the danger of making it too hot and burning your lips. But that's hardly coffee's fault.

So, it looks like this all started as a nasty rumor.

Oddly enough, I'm not really sure where this rumor started. I expected to find a definitive answer online, but I came up with lots of dead ends and guesses. Granted, we all know the internet is full of false leads, lies, and lots of sensational headlines. I shouldn't have been surprised about this one.

As far as I can tell, this all started because someone didn't like the taste of reheated coffee. They made an offhand comment about it “probably causing cancer” on a message board, and it took off. This was way back at the birth of the internet, so it's hard to say for certain the exact date and source.

But, let's be real. We're talking about humans and their opinions. I'm willing to bet these kinds of comments were going on around the time microwave ovens were invented. Maybe even before that.

The truth is that coffee is full of antioxidants. While those antioxidants may break down over time, especially if you're taking many hours to finish your cup of coffee, there is absolutely zero evidence that reheating coffee in any form will hurt your body.

As far as causing cancer?

Coffee may actually fight cancer. It's pretty farfetched to think it will suddenly reverse course and give you cancer just because you warmed up your mug of Joe.]

Proof that reheating coffee isn't bad for you

You're a smart internet user. I would never expect you to simply believe my word. So, here's some of my proof that reheating coffee isn't bad for you. Many of the things I found were repeating the same information, but here are a couple articles to get you started.

Dr. Sarah Brewer—an accidentally appropriate name for this topic—explains to the Telegraph that it's never been proven to be dangerous.  

This article covers the dangers of drinking (and reheating) old coffee, but points out that it's due to the additives (such as milk) and not the coffee itself.

There's plenty more where those came from. They all say basically the same things. There's no proof that reheating coffee is bad for you.

Does reheating coffee make it taste bad?

This isn't one of those questions that's easy to answer like “Why is the sky blue?” or “How many legs should dogs have?” The reason this is so hard to answer is because everybody's taste is different.

Think of it this way: If I like my coffee with cream and sugar, but you like your coffee black, is one of us wrong? Of course not! It just means we have different tastes, and that's perfectly fine.

One thing that is for certain is that the taste of coffee will change if you reheat it. Some people believe reheating makes it bitter and undrinkable. Some people don't really notice the difference in taste. Other people notice the difference but don't care.

It's all about the difference of opinion.

At this point, I figure the best thing I can do is provide information on how you can reheat your coffee. I also have some suggestions to help you make sure the taste doesn't change too much, as well as some options to mask the change in flavor if you need to.

Of course, you are always welcome to not reheat your coffee if that's what you prefer. I mean, why not just turn it into iced coffee if it's already too cold for your liking and you don't want to reheat it?

A woman holding a cup of coffee

How to safely reheat coffee

There are many methods to reheat coffee. You're limited only by your imagination and the equipment available to you.

The microwave method

The microwave method of reheating coffee is the method that sparked the “bad for you” debate online. For some reason, people believe that the microwave is going to somehow turn your coffee into a cancer monster. So far, there has been no scientific evidence to support this rumor.

From my experience, and my hours of research online, the only thing the microwave does to coffee is make its flavor change drastically. Some people report that microwaved coffee is terribly bitter. I didn't personally notice it that bad, but there was definitely a change in flavor. 

Coffee in a cup being reheated in a microwave.

While the microwave method may not be the best in terms of flavor, it's certainly the fastest. Here's how to get your coffee piping hot in seconds.

  • Choose a microwave-safe mug
  • Pour your cold coffee into the mug, leaving it about ¼ empty (just in case you overheat it and it boils)
  • Cover the mug with a paper towel
  • Place in microwave
  • Heat for 30 seconds
  • Stir the coffee, then test the temperature
  • If it's not hot enough, microwave it for another 10 seconds at a time, stirring between bursts, until it reaches the desired temperature

If you notice an “off” flavor after microwaving, you can add a variety of flavor enhancers to mask it. Cream is a good way to cover a flavor change. Flavored creamers work well, too.

If your coffee was already flavored, you may not even notice the change.

You may also wish to lower the power on your microwave and take it much slower. This can help prevent a “burnt” flavor.

Related Article:HOW TO MAKE COFFEE WITH A MICROWAVE? (IT WORKS)

The stove-top method

If you'd rather avoid the microwave at all costs, you can warm up your coffee on the stove. This method takes slightly longer than the microwave, but the general consensus is that it doesn't change the flavor very much.

The key to successfully using the stove to reheat your coffee is to do it very slowly. Speeding up the process by using higher heat will just burn the coffee and make it taste nasty. That's not just an opinion; that's a fact. Burnt coffee is gross.

  • Pour your cold coffee into a small pot—coated cast iron works great because it's slow to heat up, but holds heat for a long time
  • Put it on the stove set to low or medium-low heat
  • Stir every few minutes
  • Check the temperature often

The “add a splash” method

My friend hates warming his coffee back up, no matter the method used. So, he just adds new coffee to his cold coffee and drinks it that way. He calls it the “add a splash” method.

This isn't my favorite method, but it avoids the pitfalls of the other methods. The main benefit with this method is that you don't risk burning your coffee.

The main drawback, as for as I'm concerned, is that the coffee is never quite hot enough for me this way. The cold coffee cools the fresh coffee too much and I'm right back where I started.

A note on reheating temperature

This is another point of contention amongst coffee connoisseurs. The perfect coffee temperature is an often-argued point, which I won't cover in great detail here. What I do want to mention is the safety issues, since reheating coffee puts more of a risk on consumers than fresh brewing.

Brewing coffee using a machine means that the temperature is carefully monitored. It's unlikely that you will be scalded. It does happen, of course, but the chances are much lower when a coffee machine is in control.

When you reheat your coffee, you are now in control of how hot that coffee gets. This can set you up for scalding. A person can receive a burn from hot liquids within a split second of exposure. Serving temps between 160 and 180F are common, but also pose a great risk.

This report on the NCBI website covers it in detail. The main takeaway, however, is that bringing your beverage up to about 135F is usually enough to be satisfying, yet safe.

Conclusion

Whether you choose to reheat your coffee or not is entirely up to you. Don't be pressured one way or the other. If reheating coffee doesn't appeal to you for whatever reason, but you still want to drink your cold coffee, just pour it over some ice. Problem solved!

Not Everyone likes cold coffee. That's okay too. If you insist on having piping hot coffee like I do, you can use a thermos to keep it hot for many hours. Then you just pour whatever you need in a small mug, finish it quickly, and move on with your day.

Related questions

Is it safe to microwave coffee? Yes, it is safe to microwave coffee. You only need to worry about the final temperature. Also, be sure to use a microwave-safe mug.

Can you microwave coffee creamer? Yes, you can microwave coffee creamer. Some brands even encourage you to heat it up and then whisk it to make foam for your coffee. Be mindful of the temperature.