How Long Can Coffee Sit Out? Is It OK To Drink Day Old Coffee?

The vast majority of coffee lovers like us have, at one time or another, pondered whether or not it was safe to consume coffee that had been left out from the previous day.

This typically happens when you are in a hurry to get out the door but need a quick fix of caffeine or when you have run out of coffee and can’t make a fresh pot.

Whatever the case may be, you need to be aware of whether or not it is OK to consume coffee that is a day old before you find yourself in a situation that calls for it.

Key Takeaways:
Should you drink coffee that has been sitting out?

We do not advise drinking coffee that has been sitting out for a day, particularly if it has spoiled, become rancid, and acquired an unpleasant flavor or aroma. Molds have a propensity to grow in brewed coffee as well, mainly if it is kept at room temperature rather than in the refrigerator. If your coffee contains milk and has been sitting out for a day, do not drink it unless it was refrigerated.

Moreover, you must avoid drinking coffee that is more than 12 hours old unless it’s been kept in a sealed container in the refrigerator. 

Brewed coffee is only good to consume for 30 minutes or so, unless stored in an airtight thermos. This is because coffee continues to oxidize even after brewing.

Recommendations change if you use creamer, so let’s look a little further into what happens to coffee when it’s been left out.

What Happens to Coffee When it’s Left Out?

If you are leaving the coffee to sit out for more than a few hours, apart from losing its pleasant fragrance and tasting rancid, it will also develop an unpleasant bitterness or sour taste.

This happens because of a chemical process called Oxidation.

Coffee and all other foods and beverages go through a process known as oxidation when they have been left out. 

Oxidation is a chain reaction that occurs in the presence of oxygen. This process is responsible for the deterioration of the quality of food and beverage that leads to a change in odor and flavor.

Science of Coffee Oxidation

Contact with air causes roasted coffee beans to oxidize. Even though oxidation can’t be seen with the naked eye, it has a significant effect on the way coffee tastes.

This is because oxidation breaks down the flavor compounds in the coffee, which are then released into the air when the coffee comes into contact with the air.

The process of brewing coffee is oxidation in and of itself. When the coffee beans come in contact with water, they start to release their aromas, oils, and acids into the water.

Why Does Day Old Coffee Turn Bitter?

After brewing, coffee will typically maintain its freshness for around 1 to 2 hours, but once it comes in contact with oxygen, it will begin the degradation process. 

If you let your coffee sit for too long, the reaction between hydrogen and oxygen will elevate the pH level of the coffee, giving it a taste that is either bitter or “stale.” 

Because of this, you should never let your coffee sit in the pot it was brewed in for any longer than is strictly required.

If there is some leftover and you won’t be able to finish it, put it in an airtight container like a thermos bottle, or refrigerate it.

To play it safe and lower your chances of accidentally consuming harmful pathogens like molds or germs, it is strongly advised that you consume your black coffee no more than 12 hours after it has been brewed.

One way to mitigate this process is to store the liquid in the refrigerator, where it’s exposed to less oxygen and other environmental elements.

What if there’s Milk or Cream in my Coffee?

The guidelines are entirely different if you put milk or creamer in your coffee, which is something that the majority of us do.

You shouldn’t drink coffee that has been sitting out for a day and already has creamer in it. If you’ve already added creamer to your coffee, you should drink it within 1 to 2 hours.

If you leave cold brew coffee out at room temperature that has already been mixed with cream, you should drink it within two hours. 

But you can keep cold-brewed coffee fresh in the fridge for up to 2 days if you put it in an airtight container or thermos.

According to the FDA, milk and creamers are perishable and can go bad quickly. If you leave it out too long, the milk in the coffee will curdle and turn sour. 

This applies to all milk-based drinks, including latte, mocha, frappuccino, and other popular coffee beverages you get from the coffee shop.

How Long Can Brewed Coffee be Stored in the Refrigerator?

Black coffee can last more than 24 hours in the fridge.

The oxidation process can be slowed down and the coffee’s life extended by storing it in the refrigerator after it has been brewed. 

It is important to remember to store the coffee in a thermos or an airtight container since you do not want the coffee to take on the flavors of the other foods that are stored in the refrigerator.

Unless you make the cold brew concentrate, you can store it in an air-tight jar in the fridge for no more than 2 weeks. 

As I mentioned earlier, brewing the coffee and storing it at a lower temperature tends to extend your coffee’s flavor and life.

Best Ways To Drink Day Old Coffee

In an ideal world, you shouldn’t have to drink coffee that’s more than a day old too often, but if you do, there are a few ways to cut down any sour or bitter tastes.

1. Avoid reheating

You might think it’s a good idea to reheat old coffee, but don’t. The process of reheating will only speed up the oxidation of the coffee, which will make it even more bitter. 

If you want to reheat your coffee, you should only do it within the first two hours after brewing.

2. Keep it in the refrigerator.

The sooner you can cool down the brewed coffee, the less it will oxidize, which preserves the original flavor. So if you’re planning to save the coffee for a day, as soon as you are done brewing, place the coffee in the refrigerator.

3. Add ice to your day-old coffee.

Since reheating will only degrade the taste and aroma of your day-old coffee, I recommend pouring coffee over ice and also adding cream and sweetener to it. This will help minimize the bitter taste and harshness of your coffee.

Even though it might be tempting to reheat your coffee in the microwave or use your coffee machine’s warmer, this will only speed up the oxidation process and make the coffee taste more bitter and burnt. If you are going to heat coffee in a microwave, it should be done within an hour or two of brewing it.

How To Keep Coffee Safe to Drink the Next Day

Although I don’t recommend it, if you must keep your coffee safe to consume the next day, then you must keep in mind the following factors.

1. The temperature of the coffee.

The temperature at which the beverage is stored plays a significant factor in determining whether or not coffee may be consumed safely. 

If freshly brewed coffee is allowed to sit out at room temperature for an extended period of time, it will become stale, bitter, and sour, rendering it undrinkable.

On the other hand, consuming hot coffee or keeping it cold in order to drink it at a later time does not compromise its safety. 

Be careful not to burn the coffee by reheating it a number of times, and don’t drink coffee that has been stored in the refrigerator for more than a day.

2. Addition of milk/cream.

One of the most critical factors that determine how long a cup of coffee can stay safe to consume is whether or not it contains milk or cream. The life of your coffee will be significantly shortened if you add milk to it because dairy has a propensity to spoil rapidly if it is not refrigerated.

Once you add ingredients like milk, cream, and sugar, those elements will break down and grow harmful bacteria much faster. 

If you drink your coffee black, without any extra milk or cream, it will probably taste somewhat better for a slightly longer period of time.

3. Type of container used to store coffee.

If you put your brewed coffee in a container or mug with a lid, the oxidation process will take longer, and the coffee will last longer. This means that it will take longer for your morning coffee to get bitter.

On the other hand, if you use a standard mug that does not have a lid or a cover, don’t expect your coffee to last long. 

Therefore, if you are a person who enjoys sipping their coffee slowly, it is recommended that you choose a container or mug that has a lid.


In general, consuming coffee that is at least one day old should only be done as a last resort (unless you are talking about cold brew variants). Even though you won’t feel sick after drinking it, that doesn’t mean you should do so anyhow. 

If you often find yourself making more than you can drink at once, invest in a good thermos that will prolong the vitality of your coffee for a few hours. 

It can keep the coffee hot and relatively fresh for a few more hours longer since it doesn’t allow the air to contact the coffee and slow down the oxidization.

Frequently Asked Questions (FAQs)

1. How long can coffee with milk sit out?

According to the FDA, products that spoil quickly, such as milk, should not be left out of the refrigerator for longer than two hours. The same thing should be done with coffee and milk that have been left out for a while. Consequently, if you want to enjoy your coffee with milk at a later time, you will need to make sure that it is stored in the refrigerator.

2. Should coffee be refrigerated once brewed? 

If you’re planning to save the coffee for a day, then you should transfer the coffee to an airtight container and then place it in the refrigerator. Although brewed coffee can be stored in the refrigerator for up to a week, the flavor and aroma will not be as pleasant as they are in a cup of coffee that has just been brewed.

3. Does coffee go bad overnight?

The coffee that has been sitting out overnight is still safe to drink, but it will taste bitter and will have a rancid aroma. The flavor of coffee that has been left out at room temperature overnight will be noticeably more astringent than coffee that has been stored in the refrigerator, but it will not make you sick.

4. How long does the caffeine stay in brewed coffee?

The caffeine content would remain the same in your cup of coffee after a few hours as it was just brewed. Caffeine, in comparison to other components of flavor that are prone to evaporation or other forms of loss after brewing, is stable and does not dissipate. The absence of aroma and flavor is something you could notice, but you won’t miss the caffeine.

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Amit Gupta

Hi, my name is Amit Gupta, and I am the owner and contributor at Cafeish. My obsession with coffee started when I received my first French press as a gift almost ten years ago. Since then, my love of coffee – and the number of coffee gadgets I own – has grown considerably.

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