Is caffeine/dehydration causing stomach issues

Has anyone who suffers from stomach issues on the run ever pegged it on caffeine and/or dehydration in their every day life?

To be a little more specific: my background is running. I was a fairly competitive distance runner in middle/high school, and I never had stomach issues until college. Never drank coffee prior to college years. I started experience the running “runs” here and there through college…which is also the time I started consuming large amounts of coffee and other caffeinated drinks to aid studying.

Fast forward to today. I’m now 35 and have had on and off stomach issues when running pretty much ever since. And I am still a big coffee drinker. When I really think about it, I feel as if the “runs” are more common during weeks when I’m not actively prioritizing hydration outside of my workouts. I have days where I get busy at work and I realize that I may have drank a coffee or 2, and have had zero water/electrolytes all day.

For the next few weeks I will paying very close attention to this, but was wondering if anyone else has had similar issues, and if you had resolved them simply by hydrating your system better.


Caffein can give you stomach issues, but not in the usuals coffee dosing. Most people will experience such stomach issues when using caffeinated supplements (like caffeine pills, or a lot of caffeinated energy gels).

On the other hand, imagine if any time someone gets dehydratated gets “runs” and stomach ache, seems like a weird way to get them to save water (probably will drink less because of the stomach ache and loose more because of the “runs” if i get you right). So its not the proper dehydratation response. You should get thirsty, and you can get cramps, and feel tired, fatigued maybe dizziness. But I don’t think that dehydratation explains your “runs”. Your “runs” may explain dehydration if you don’t compensate it properly.

In summary, I don’t think that I would blame caffeine and “dehydration” for your stomach issue.

You can try to quit coffee and see whats happens, may be your stomach is extra sensible to caffeine (usually it generate tolerance, so if you have been drinking coffee for years it will be weird, but worth a try). You should ALWAYS get proper hidratation.

If your stomach issues persist you should go to a doctor and get medical advise, you can have a gastrointestinal disease that could explain better your symptons than caffein and dehydratation.

I hope I was helpful. And lets wait if someone thinks differently.

Watch out for fructose. That also can cause GI issues

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Dehydrating yourself will mess you up for a good week. All the moving solids in there seem to adhere to the walls and quit moving.

Coffee contains a surprising amount of soluble fiber (yes, I know Google says it doesn’t). It’s also acidic. It might not be the caffeine.

Thank you for all the suggestions and advice everyone. After seeing and reading multiple comments mentioning fructose as a possible stomach issue source, I may have to be more honest with myself about my sugar addictions as well! I never eat high fructose foods/gels during workouts. HOWEVER, I do snack on a lot of crappy processed sugar treats outside of training. I’m going to cut all of it out for the remainder of my current block/phase and see how my stomach reacts.

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I love coffee but it causes my gut/digestion to go a bit wonky. My gut gets sensitive to what I eat with regular coffee intake. I recently stopped coffee for 12 weeks and my digestion and gut health was perfect, I could eat pretty much whatever I wanted with no issues. I just tried a couple days of coffee and immediately noticed my gut felt different and was “twinging”. I’ve known this but love coffee so go back and forth with it.

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Lactose intolerance hit me at about 40 years of age.

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I was circa 35 year old when my stomach issues started, I looked round for answers like dehydration/ caffeine but circa 5 years later it turned out to be a more major underlying problem, bowel cancer. A simple blood test (showing an iron deficiency) put the docs onto it and in hindsight I wish I’d done the simple test back then and I possibly could have avoided the major surgery 5 years later :thinking: Its almost guaranteed that your problems aren’t the same as what I had @teamsuchevich but if you haven’t already done it, Id urge you to get a blood test done. It will rule it in or out (as most likely) and may also indicate what the real problems behind your stomach issues are.


Well that scared the s*** outta me! I’m really glad to hear that you’re ok now. I have actually been planning to get some blood work done, not because of the stomach issue, but just because I havn’t done it in a long time and I’m curious about my markers as I am in the middle of a pretty fatiguing block. I will definitely mention this specifically when I do go.

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