why does coffee make me nauseous
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Why Does Coffee Make Me Nauseous and What to Do About It?

For countless individuals worldwide, coffee serves as a cherished morning ritual or a cozy afternoon pick-me-up. However, an intriguing and uncomfortable question lingers for some: “Why does coffee make me nauseous?” Let’s delve into the scientific underpinnings behind this perplexing reaction to the beloved brew.

The Chemical Composition of Coffee


Coffee is much more than just a flavorful beverage. It’s a complex mixture of chemicals, some of which are introduced during the roasting process while others are natural constituents of the coffee bean. These compounds contribute to the flavor, aroma, and physiological effects of coffee. Here’s a closer look at some of the significant components:

1. Caffeine

The most recognized compound in coffee. It’s a central nervous system stimulant that can boost alertness and ward off feelings of fatigue. The caffeine content can vary depending on the type of bean and the brewing method, but a typical 8-ounce (240-milliliter) cup of coffee contains approximately 95 milligrams of caffeine.

2. Chlorogenic Acids (CGAs)

These are a group of polyphenolic compounds found in coffee. CGAs have been the focus of research due to their potential antioxidant, anti-inflammatory, and anti-hypertensive properties. However, during the roasting process, some CGAs break down into quinic acid and caffeic acid, affecting the overall flavor of the coffee.

3. Lipids

These include oils and fats that contribute to the mouthfeel and flavor of coffee. The Maillard reaction, which occurs during roasting, affects these lipids and helps develop the complex flavors we associate with coffee.

4. Water-Soluble Proteins

About 10-13% of coffee beans consist of proteins, which contribute to the body and flavor of the coffee. These proteins can react with tannins during brewing, forming complexes that can make coffee taste more astringent.

5. Carbohydrates

Coffee beans contain both simple sugars and polysaccharides (like cellulose). Roasting breaks down many of the sugars, which can participate in the Maillard reaction, contributing to the browning of the beans and the formation of many aromatic compounds.

6. Trigonelline

Another alkaloid found in coffee, though in smaller amounts than caffeine. During roasting, it degrades and forms nicotinic acid (or niacin), pyridines, and other compounds that contribute to the aroma and flavor of coffee.

7. Kahweol and Cafestol

These are diterpenes found in coffee oil. They have been of interest due to their potential effects on human health, specifically their impact on cholesterol levels. The amount of these diterpenes in a cup of coffee can vary depending on the brewing method.

For instance, paper filters can trap most of these compounds, while methods like the French press allow more of them into the final beverage.

8. Acids

Coffee contains a variety of acids, such as citric, malic, formic, acetic, and quinic acids. These acids contribute significantly to the taste profile of the coffee, offering bright, tangy, sparkling or crisp qualities. The perceived acidity in a cup of coffee can be influenced by factors like bean origin, roasting degree, and brewing method.

9. Aromatic Compounds

Hundreds of volatile compounds contribute to the aroma of coffee, resulting from the complex reactions that occur during roasting. These can include sulfur-containing compounds, aldehydes, ketones, esters, and pyrazines.

10. Minerals and Micronutrients

Coffee beans contain essential minerals like potassium, magnesium, and niacin. Some of these minerals, particularly potassium, can be found in relatively high amounts in brewed coffee.

The chemical composition of coffee is vast and varied, resulting in the intricate flavors, aromas, and physiological effects that coffee lovers across the world cherish. Understanding these compounds can offer deeper insights into what makes each cup of coffee unique and how various factors, from roasting to brewing, influence the final beverage.

Main Reasons for Coffee-Induced Nausea


Coffee is a beloved beverage for many, but for some, it can cause digestive disturbances like nausea. The reasons behind coffee-induced nausea can be multifaceted, rooted in both the beverage’s composition and how our body reacts to it. Here are the primary factors contributing to this unease:

1. Caffeine Sensitivity

  • Stimulation of Stomach Acid: Caffeine can boost stomach acid production. For individuals sensitive to this effect, the increased acid can irritate the stomach lining, leading to a feeling of nausea.
  • Accelerated Digestion: Caffeine can stimulate faster bowel movements, which, for some people, can be uncomfortable and lead to a queasy feeling or even diarrhea.
    Metabolic Variations: It’s worth noting that people metabolize caffeine at different rates. This means that some individuals may experience the effects of caffeine more intensely and for more extended periods than others.

2. Acidity of Coffee

  • Irritation of Stomach Lining: Coffee is naturally acidic. This acidity can irritate the stomach lining, especially in individuals already prone to acid reflux or other gastric ailments.
  • Aggravation of Acid Reflux: The acidic nature can also lead to acid reflux, where acid from the stomach moves up into the esophagus, causing heartburn and nausea.

3. Stimulation of Gastric Acid Production

Beyond caffeine, coffee contains other compounds, such as catechols, that can increase gastric acid secretion. This rise in stomach acid can heighten feelings of nausea, especially if the coffee is consumed in large quantities or on an empty stomach.

4. Effects on the Lower Esophageal Sphincter (LES)

Coffee can relax the LES, a muscular valve that separates the stomach from the esophagus. When relaxed, it may allow stomach acid to enter the esophagus, leading to feelings of heartburn and nausea.

5. Consumption on an Empty Stomach

Drinking coffee on an empty stomach can intensify its effects. Without food to act as a buffer, the acidic nature and stimulating compounds in coffee can directly irritate the stomach lining, leading to a heightened risk of nausea.

6. Personal Sensitivities and Allergies

Some individuals might have specific sensitivities or even mild allergies to certain compounds in coffee. This can manifest as stomach discomfort or nausea upon consumption.

7. Additives in Coffee

Ingredients added to coffee, like certain dairy products, flavored syrups, or even artificial sweeteners, can also be culprits. For example, those with lactose intolerance might experience nausea after consuming coffee with regular milk.

While coffee is enjoyed by many without any adverse effects, it’s evident that its compounds can interact with our digestive system in ways that might not always be pleasant.

For those who experience nausea after drinking coffee, understanding these factors can be the first step in finding a solution or making necessary adjustments.

Additional Factors Contributing to Nausea


1. Medications

Numerous medications, including some antibiotics and antidepressants, can cause nausea as a side effect. It’s crucial to consult with a healthcare professional if a drug might be the culprit.

2. Gastrointestinal Issues

Gastroenteritis, often due to infections, disrupts digestion leading to nausea and vomiting. Conditions like GERD, where stomach acid flows back into the esophagus, and peptic ulcers also frequently result in nausea.

3. Pregnancy

Many pregnant women experience “morning sickness” or nausea, especially during the first trimester, possibly due to hormonal changes.

4. Emotional Stress

The mind-gut connection is profound; acute anxiety or chronic stress can often manifest as nausea due to the release of stress hormones.

5. Dietary Factors

Overeating, certain food intolerances, and excessive alcohol consumption can strain or irritate the digestive system, leading to nausea.

6. Environmental Triggers

Motion sickness arises from sensory conflict, causing dizziness and nausea. Additionally, strong odors can sometimes trigger a nauseous response.

Nausea has diverse origins, ranging from physiological to environmental. Understanding these can help individuals better manage this common discomfort.

Tips to Minimize Coffee-Induced Nausea


Coffee-induced nausea can be discomforting for many. Here are some tips to help minimize or prevent this sensation:

  • Reduce Coffee Strength: Consider drinking a weaker brew or diluting your coffee with water or milk. Less concentrated coffee can be less irritating to the stomach.
  • Opt for Low-Acidity Beans: Some coffee beans are marketed as low-acid, which might be gentler on sensitive stomachs.
  • Eat Before Drinking: Drinking coffee on an empty stomach can exacerbate its acidic effect, potentially leading to nausea. Try consuming your coffee after a meal or snack.
  • Limit Additives: High amounts of sugar, artificial sweeteners, or certain creamers might contribute to stomach upset. Experiment to find which additives, if any, affect you and reduce or eliminate them.
  • Change Brewing Method: Cold brew coffee, for instance, is often touted as smoother and less acidic than hot brewed coffee. It might be worth giving alternative brewing methods a try.
  • Drink Smaller Amounts: Instead of a large mug, consider smaller servings spread throughout the day to give your stomach a break.
  • Stay Hydrated: Coffee is a diuretic, which means it can lead to dehydration. Drinking water alongside or after your coffee can help counteract this effect and reduce stomach discomfort.
  • Adjust Coffee Grind Size: If you’re using a French press or espresso maker, the grind size can affect extraction and, consequently, the coffee’s acidity. A coarser grind for the French press or a finer one for espresso might help.
  • Limit Caffeine: High caffeine levels can contribute to nausea for some individuals. Consider switching to decaf or a blend with lower caffeine content.
  • Monitor Consumption Time: Some people find that drinking coffee later in the day or close to bedtime can upset their stomach more. If this is the case, consider limiting your coffee consumption to mornings.
  • Listen to Your Body: Everyone’s tolerance and reaction to coffee are unique. If a specific brand, type, or preparation method consistently causes discomfort, it might be best to switch things up or reduce your consumption.

For many, coffee is a beloved daily ritual. By making slight adjustments to how you consume it, you can continue to enjoy its benefits without the unwanted side effects. Remember, if nausea persists or is severe, it’s essential to consult with a healthcare professional.


Coffee, while being a global favorite, can sometimes have adverse effects on our digestive system. By understanding the reasons behind the unsettling question, “Why does coffee make me nauseous?”, we can make informed choices and continue enjoying our brew, minus the discomfort.

AboutCorinne Switzer

Corinne is an avid reader and takes a keen interest in conspiracy theories. When not busy with her day job, she likes to indulge the writer in her and pens columns on a wide range of topics that cover everything from entertainment, healthy living to healthcare and more.