Can Caffeine Worsen Diarrhea? What You Need to Know

October 12, 2025 •

4 min read

Over 60% of people report that coffee has an effect on their bowel movements. The question is, can caffeine worsen diarrhea, and for whom? The answer is yes, caffeine can indeed contribute to or worsen diarrhea, though the effect is highly dependent on the individual and other factors.

Quick Summary

This article explores the link between caffeine consumption and diarrhea, detailing the physiological mechanisms involved, including increased gut motility and hormonal responses. It compares the effects of different caffeine sources and provides practical tips for managing intake to reduce digestive discomfort.

Key Points

Stimulates Gut Motility: Caffeine increases contractions in the colon, which can speed up digestion and lead to diarrhea, especially with excessive intake.
Triggers Hormonal Response: Coffee stimulates the release of gastrin, a hormone that initiates intestinal movement, contributing to its laxative effect.
High Acidity and Additives: The acidity of coffee and common additions like dairy or artificial sweeteners can also irritate the stomach and worsen diarrhea.
Individual Sensitivity is Key: Digestive response to caffeine varies greatly depending on an individual's sensitivity and any underlying conditions like IBS.
Mitigate Effects with Smarter Choices: Opting for cold brew or darker roasts, avoiding additives, and drinking caffeine with food can help reduce digestive upset.
Decaf Still Has Some Impact: Even decaffeinated coffee contains some acids that can affect sensitive stomachs, though the effect is less potent than with caffeinated versions.

The Science Behind Caffeine and Your Gut

Caffeine is a potent stimulant that affects more than just your central nervous system; it also has a significant impact on your gastrointestinal tract. This is because caffeine can trigger several physiological responses that influence how food and waste move through your system, potentially leading to or worsening diarrhea.

How Caffeine Increases Bowel Motility

One of the primary ways caffeine affects digestion is by increasing gut motility. Motility refers to the muscular contractions of the digestive tract that propel contents forward. Research shows that caffeinated coffee can stimulate colonic motor activity significantly more than decaffeinated coffee or even a glass of water. This acceleration can cause food to pass through the intestines too quickly, leaving less time for the colon to absorb water. The result is looser, more watery stool—the key characteristic of diarrhea.

The Role of Hormones and Stomach Acid

Caffeine also influences the production of certain hormones that regulate digestion. Specifically, it can trigger the release of gastrin, a hormone that stimulates muscle contractions in the stomach and intestines. In addition, caffeine increases the production of gastric acid in the stomach. For some individuals, this increased acidity can cause stomach upset, which may accompany loose stools or contribute to overall digestive distress. These combined hormonal and acidic effects create a perfect storm for accelerating the digestive process.

Other Factors That Exacerbate the Effect

While caffeine is a major player, other components and factors can worsen its impact on digestion:

Additives: The sugar, artificial sweeteners, and dairy products often added to coffee can trigger or exacerbate diarrhea. Lactose intolerance, for example, is a common cause of digestive issues and, when combined with caffeine's stimulating effect, can significantly increase discomfort.
Acidity: The natural acidity of coffee, particularly lighter roasts, can irritate the stomach lining and cause symptoms in sensitive individuals.
Stress and Anxiety: Caffeine can increase feelings of anxiety and stress. Since the gut and brain are closely connected, psychological stress can worsen symptoms in those with sensitive digestive systems, such as people with Irritable Bowel Syndrome (IBS) or Inflammatory Bowel Disease (IBD).

Sources of Caffeine and Their Digestive Impact

Not all caffeinated products are created equal when it comes to digestive impact. The type of beverage, roasting process, and preparation method can all play a role.

A Comparison of Caffeine Sources and Digestive Effects


Caffeine Source	Typical Digestive Impact	Contributing Factors
Filtered Coffee	High potential for irritation and laxative effect.	High acidity, longer brewing process extracts more irritants, high caffeine content.
Espresso	Less irritating for many.	Shorter brewing time extracts fewer irritants, though caffeine content per ounce can be high.
Cold Brew Coffee	Significantly lower acidity, often gentler on the stomach.	Steeping process with cold water reduces the extraction of irritating acids.
Black or Green Tea	Generally less irritating than coffee.	Lower caffeine content than coffee, fewer irritants.
Energy Drinks	High potential for diarrhea.	High caffeine content often combined with large amounts of sugar and artificial sweeteners.
Dark Chocolate	Minimal laxative effect from caffeine alone.	Lower caffeine per serving, but contains compounds and fats that can affect digestion.

Strategies for Managing Caffeine-Induced Diarrhea

If you find that caffeine is contributing to your diarrhea, you don’t necessarily have to give it up entirely. A few simple changes can make a big difference:

Monitor your intake: Pay close attention to how your body reacts to different levels of caffeine. The FDA considers up to 400 mg of caffeine per day safe for most healthy adults, but individual tolerance varies greatly.
Switch to decaf or half-caff: This is often the most effective solution. Decaffeinated coffee still has some of the beneficial compounds of coffee but with far less of the stimulating caffeine.
Drink with food: Consuming caffeine on an empty stomach can increase its acidic impact. Pairing your coffee or tea with a meal can help buffer the effects and slow absorption.
Opt for darker roasts or cold brew: If you are sensitive to acidity, choosing a dark roast or cold-brewed coffee can be gentler on your stomach. Darker roasts have lower acidity because the roasting process breaks down more of the acidic compounds.
Consider dairy-free alternatives: If you suspect lactose intolerance is contributing to your symptoms, swap cow's milk for plant-based alternatives like almond, soy, or oat milk.
Hydrate adequately: Because caffeine has a mild diuretic effect, it's important to drink plenty of water throughout the day to stay hydrated, especially if you are experiencing loose stools.

Conclusion

For many, moderate caffeine consumption is a pleasant daily habit with no adverse digestive effects. However, for sensitive individuals or those with underlying gastrointestinal conditions, caffeine can indeed worsen diarrhea by speeding up intestinal transit and increasing stomach acid. The key is to listen to your body and identify your personal tolerance levels. By adjusting the type of beverage, the quantity, and your habits, you can often mitigate discomfort and continue to enjoy your favorite caffeinated drinks without suffering the unwanted side effects. If persistent digestive issues continue, it is always best to consult a healthcare provider for personalized advice.

For more information on digestive health, consult a reliable resource like the Canadian Digestive Health Foundation at https://cdhf.ca/en/.

Frequently Asked Questions

Caffeine is a stimulant that can increase gut motility, meaning it makes the muscles of the digestive tract contract more frequently. This can speed up the passage of waste through the intestines, reducing the time for water absorption and resulting in loose stools or diarrhea.

Both the caffeine and other compounds in coffee can play a role. The stimulating effects on gut motility are largely attributed to caffeine, but coffee's natural acidity and other compounds can also irritate the stomach. However, decaffeinated coffee can still have a mild effect, suggesting other coffee components are also involved.

While green tea contains caffeine and can have a mild stimulating effect, its caffeine content is generally lower than coffee. It is less likely to cause digestive issues, but it can still affect sensitive individuals. The impact often depends on the quantity consumed.

To mitigate diarrhea from caffeine, try these steps: reduce your intake, switch to decaf, drink it with food instead of on an empty stomach, opt for a low-acid cold brew or dark roast coffee, and avoid sugary or dairy-based additives.

Yes, for some sensitive individuals, regularly consuming large quantities of caffeine, particularly from sources like multiple cups of strong coffee or energy drinks, can potentially contribute to or exacerbate chronic loose stools.

Yes. People with existing digestive conditions like Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), or those with lactose intolerance are more sensitive to the effects of caffeine and are more likely to experience diarrhea.

Energy drinks often contain high levels of caffeine combined with significant amounts of sugar and artificial sweeteners. These additives can have a laxative effect and exacerbate digestive distress in many people, making the overall impact more severe than coffee alone.