Why Coffee Can Make Your Stomach Upset[and How To Stop It]

Article from: Clark, Coffee & Wellness

Why coffee can upset your stomach?

Acidity,Caffeine,Empty Stomach,Bad Beans and Ingredients


One of the primary culprits of an upset stomach after drinking coffee is acidity. The pH of coffee, a measure of how much acid is in the coffee, hovers around 5. The lower the pH, the more acidic something is.

For comparison, water has a pH of 7, and a lemon’s pH is around 2.5.

Coffee’s pH varies depending on how the coffee beans are roasted and how it’s brewed, which affects the concentration of acids like chlorogenic acid, quintic acid, and citric acid in the cup of coffee.

When coffee reaches the stomach, it makes the stomach ramp up stomach acid production and actually secrete more gastric acid. This can lead to heartburn, indigestion, acid reflux, and general stomach upset.

Coffee’s acidity can also break down the protective mucosal barrier of your digestive system, which can irritate ulcers and cause other problems in the digestive tract. These side effects of drinking coffee are particularly strong when you have it on an empty stomach.

Can coffee cause stomach ulcers? No, coffee can’t cause stomach ulcers directly, but coffee drinking can exacerbate stomach pain and other symptoms if people with ulcers drink too much coffee.


Another reason why coffee upsets your stomach is its caffeine content. If you don’t experience an upset stomach after drinking decaf coffee, caffeine is probably the reason why you’re having digestive issues.

One of the primary effects of caffeine on the digestive tract is stomach irritation and gastrointestinal distress. It stimulates movement in the digestive tract in some people. Too much caffeine can also have a laxative effect and cause discomfort in the lower digestive tract.

Caffeine’s main effect is on the nervous system, and too much caffeine can make you feel very jittery. The caffeine from a single cup of coffee can stay in your system for hours: the average person has about half the caffeine from their coffee still in their bloodstream after 5 or 6 hours.

That jittery, overstimulated feeling makes some people feel like their stomach is upset or hurting, making the digestive effects of caffeine even stronger.

If you’re cutting back the amount of coffee or caffeine you consume, you may actually be feeling sick because you’re going through caffeine withdrawal. Wean yourself off of caffeine slowly to avoid these effects.


Drinking coffee on an empty stomach can also cause abdominal pain and stomach discomfort. When you don’t have food with your coffee, there isn’t anything else in your stomach to buffer the acidity of coffee, which can irritate the stomach lining and intestinal tract.

When you drink coffee without eating, certain compounds in the coffee can interact directly with your digestive tract. They’re also available in higher concentrations when you only drink coffee, amplifying the effects of the irritants on your stomach.

Many people who practice intermittent fasting will drink coffee on an empty stomach. They need their morning coffee, and drinking black coffee doesn’t break their fast because it only has a few calories per cup. Poor-quality coffee on an empty stomach, however, can lead to stomach aches.

Coffee itself also increases gastric motility, which is why coffee can make you feel like you need to poop and why some people feel it gives them diarrhea. Drinking coffee on an empty stomach can make these effects worse for people who experience them.

Can too much coffee upset your stomach? Too much coffee can upset your stomach if it’s too acidic or if you drink cheap, low-quality coffee. Low-acid, high-quality coffee is much less likely to upset your stomach.


The quality of your coffee can also determine whether it upsets your stomach. Cheap coffee can have contaminants like fungi that can cause health issues, including stomach irritation. Some toxins from the fungi survive the roasting process and can make you sick.

The size of the coffee grounds you use to make your coffee affects the acidity of the coffee, too. Coffee made with coarser grounds tends to be less acidic than coffee made from finer grounds. If you’ve been using finely ground coffee beans, you may have inadvertently hurt your stomach.

Some cheap coffee isn’t ground to a consistent size. There are large and small coffee grounds all mixed up together. The resulting cup of coffee can be more acidic than you might expect, and it can taste pretty funky, too.

For coffee drinkers with lactose intolerance, the culprit may be the milk in their latte, not the coffee itself. If you’re lactose intolerant, even small amounts of milk can cause bloating, stomach upset, and other major digestive problems.

If you’re curious whether you’ve developed a lactose intolerance, try keeping a food log and take note of the foods that you eat before you have stomach problems. Also, try switching to a non-dairy “milk” or creamer to see if that helps ease your stomach.

Why do I feel sick after drinking coffee? You feel sick after drinking coffee because something in the coffee is upsetting your stomach. Usually, these include high levels of acids, caffeine, or something you’ve added to your coffee.


Opt low-acid coffee beans.

Opt dark over light roasts.
Drink cold brew instead of hot.

Opt low-caffeine coffee beans

Opt for a coarser grind.

If coffee irritates your stomach, you don’t have to just give up coffee altogether! There are many things you can do to brew a cup of stomach-friendly coffee. You can have your cup of coffee and drink it, too.

People who are tempted to quit coffee often forget that coffee is actually really good for you. Coffee has so many health benefits: it’s full of antioxidants and can even reduce your risk of developing certain types of cancer. It won’t stunt your growth, either.

Even patients with irritable bowel syndrome (IBS) can enjoy coffee if they choose the right type and brew it the right way. Stomach-friendly coffee can absolutely be a regular part of your diet if you have IBS.


One of the best ways to make a stomach-friendly cup of coffee is to use low-acid coffee. Some varieties of coffee naturally have less acid, which means they’re also better for your digestive system.

The environment and soil coffee is grown in can affect the acidity of the coffee beans. Coffee that grows at a higher altitude tends to have fewer acids. Even growing coffee in shade can reduce its acidity.

The roasting and brewing processes also change the acid content of coffee. For example, lighter roast coffee tends to be more acidic than dark roast coffee. Gold coffee is even less acidic than traditional roasts. Espresso is much more acidic than standard coffee.


The temperature of the water you use to brew your coffee can also make it easier or harsher on your stomach. Using a standard coffee maker may actually be upsetting your stomach. Cold brew takes longer to make, but it’s ultimately better for your stomach.

Cold brew coffee is much easier on the stomach than coffee brewed with hot water. The temperature of the water you use to make your coffee actually has a big effect on what’s in your cup of coffee, including the compounds that can cause stomach upset.

Scientific tests show that hot coffee is more acidic than cold brew coffee. Brewing coffee with cold water extracts fewer stomach-irritating chemicals and compounds, including the many different acids that occur naturally in coffee beans.

All this means that your cup of hot coffee can have extra acid that may be irritating your stomach. Simply switching to a cold brew may help ease your stomach discomfort and help you feel better after drinking a cup of coffee.


Decaf coffee can help ease an upset stomach if it’s caused by drinking too much caffeine. Most of the time stomach upset is caused by coffee’s acidity, but caffeine can contribute to stomach issues, especially if you’re very sensitive to caffeine.

If you find that most of your stomach issues also happen when you’re feeling the caffeine jitters, give decaf coffee a try. You’ll be able to rule out whether caffeine, acid, or something else is the culprit that’s making your stomach feel uneasy.

Ground size

The size of the coffee grounds can also affect acidity. The smaller the ground, the greater the surface area exposed relative to volume, which can lead to more acid being extracted in the brewing process (5Trusted Source).

Therefore, using a finer grind may result in a more acidic cup of coffee.