Why Does Caffeine Hurt on an Empty Stomach?

December 24, 2025 •

3 min read

Approximately 9 in 10 coffee drinkers begin their day with a cup of joe, yet a significant number experience unpleasant stomach pain if they haven't eaten beforehand. This discomfort can range from mild indigestion to sharp, burning sensations and is caused by several physiological reactions triggered by caffeine and coffee's natural acidity when consumed on an empty stomach. Understanding the science behind this common issue can help you enjoy your morning brew without the side effects.

Quick Summary

Drinking caffeine on an empty stomach can trigger stomach pain by increasing gastric acid production, irritating the stomach lining, and causing acid reflux. The rapid absorption of caffeine and a spike in the stress hormone cortisol can also exacerbate digestive issues for sensitive individuals.

Key Points

Increased Gastric Acid Production: Caffeine stimulates the stomach to produce more hydrochloric acid, which can irritate the stomach lining when there's no food to buffer it.
Relaxed Esophageal Sphincter: Caffeine can relax the lower esophageal sphincter, allowing stomach acid to flow back into the esophagus and cause acid reflux or heartburn.
Rapid Caffeine Absorption: Drinking caffeine on an empty stomach leads to faster absorption, which can intensify its effects, causing anxiety, jitteriness, and increased heart rate.
Spiked Stress Hormone (Cortisol): An empty stomach can cause an exaggerated cortisol spike from caffeine, potentially disrupting metabolism and increasing feelings of anxiety.
Stimulated Bowel Motility: Caffeine's stimulatory effect on the colon can be more pronounced on an empty stomach, leading to abdominal cramps and discomfort, especially for those with IBS.
Effective Mitigation Strategies: Eating a balanced meal before coffee, choosing low-acid roasts, and opting for cold brew can help prevent or minimize stomach pain.

The Core Culprits: Increased Acidity and Gastric Irritation

Consuming caffeine on an empty stomach can lead to stomach discomfort for several reasons related to how it affects the digestive system. Coffee, in particular, is naturally acidic, and this acidity can be more problematic without food in the stomach to buffer it.

Stomach Acid Production and Irritation

Caffeine, even in decaf coffee, stimulates the production of hydrochloric acid. Without food, this increased acid can irritate the stomach lining, causing burning and indigestion. Caffeine can also relax the lower esophageal sphincter, allowing acid to reflux into the esophagus and causing heartburn. This is especially true for those with conditions like GERD.

Faster Absorption and Body's Response

Drinking caffeine on an empty stomach results in quicker and more concentrated absorption, intensifying its effects.

Effects of Rapid Absorption

Jitters and Anxiety: Rapid absorption can cause a sudden energy surge, leading to jitters and anxiety.
Increased Heart Rate: A faster heart rate or palpitations can occur due to quick absorption.
Digestive Motility: Caffeine stimulates colon contractions. On an empty stomach, this can cause cramping and urgency, particularly for those with IBS.

Cortisol Release

Caffeine increases cortisol, a stress hormone that naturally peaks in the morning. Caffeine on an empty stomach can cause an unnatural spike, potentially affecting metabolism, sleep, and mood.

How to Avoid Caffeine-Related Stomach Pain

Several strategies can help you enjoy your morning caffeine without stomach discomfort.

Practical Tips to Reduce Discomfort

Eat Before: Eating a small meal or snack before caffeine helps buffer acid and slows absorption.
Choose Lower-Acid Options: Dark roasts or cold brew coffee are less acidic than light roasts.
Add Dairy or Alternatives: Milk or cream can help neutralize acidity.
Stay Hydrated: Drinking water before caffeine can help prepare your digestive system.
Consider Alternatives: Green or black tea might be gentler, or you can switch to decaf.

Comparison of Coffee Roasts and Brewing Methods


Feature	Light Roast Coffee	Dark Roast Coffee	Cold Brew Coffee
Acidity Level	Higher	Lower	Significantly Lower
Stomach Impact	More likely to cause irritation on an empty stomach due to higher acidity	Less irritating than light roasts due to lower acid content	Gentlest on the stomach; ideal for sensitive individuals
Flavor Profile	Brighter, more complex, and fruity notes	Bolder, richer, and often more bitter	Smoother, less bitter, and often sweeter tasting
Caffeine Content	Typically higher	Often perceived as lower, but similar per bean; lower overall concentration if brewed cold	Can be higher, but absorption is slower and less shocking to the system

Conclusion: Listen to Your Body

While some people can drink caffeine on an empty stomach without issues, it causes significant discomfort for many due to increased acidity, rapid absorption, and hormonal responses. By understanding these effects and implementing strategies like eating first, choosing lower-acid options, or adding milk, you can often mitigate stomach pain. If severe discomfort persists, consult a healthcare professional to rule out underlying conditions. Listening to your body is crucial for determining the best approach for your digestive health.

The Healthline guide on coffee and stomach issues: A reliable source on digestive health related to coffee consumption.

Frequently Asked Questions

Yes, black coffee can be particularly harsh on an empty stomach because it lacks milk or cream, which can act as a buffer against its natural acidity. This can exacerbate stomach acid irritation and lead to pain or reflux.

While tea is generally less acidic than coffee, the caffeine it contains can still stimulate stomach acid production. If you are sensitive to caffeine, drinking tea on an empty stomach could still cause discomfort, although it's often milder than with coffee.

To quickly relieve stomach pain from caffeine, try drinking a glass of water to help dilute stomach acid. You can also eat something bland and high in fiber, like a banana or oatmeal, to help absorb excess acid.

Yes, adding milk or a plant-based alternative to your coffee can help by acting as a buffer, neutralizing some of the coffee's acidity and making it gentler on your stomach lining.

Yes, cold brew coffee is often better for a sensitive stomach. The cold-steeping process extracts fewer acidic compounds than hot brewing, resulting in a smoother, less acidic final product that is gentler on the digestive system.

Yes, the rapid absorption of caffeine on an empty stomach can lead to a quicker and more intense surge of caffeine, which can amplify feelings of anxiety and jitters in sensitive individuals.

Not everyone is equally sensitive to caffeine or the acidity of coffee. Factors like individual tolerance, body size, metabolism, and genetic predispositions all play a role in how a person's digestive system responds.