My question is as simple as it sounds. I want to know which constituent in coffee makes me poop, chemical or physical (particle).

I'm sure everyone has experienced it. You drink a (couple) cup(s) of coffee and a few minutes later you'll find yourself rushing to the toilet. I personally don't drink a lot of coffee. I drink one cup a day (only from We. to Fr.) and occasionally a cup on Weekends.

What ingredient causes this laxative effect?

  • Is it the caffeine?
    • If so, why doesn't energy drinks have a similar effect?
  • Is it something out of the coffee bean itself?
  • Do only special types of coffee (bean) have this laxative effect?

I tried googling a bit, but haven't found a meaningful answer. Seems like scientists can't agree which ingredient causes it or whether it's even scientifically proven that coffee has a laxative effect.

  • As we don't have access to the test subject how are we and you for that matter going to confirm that this has been answered (albeit there is a definite test result)?
    – EdChum
    Jan 28, 2015 at 14:51
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    well this question appears very domain specific to you, I can happily consume quite a bit of coffee and the worst that can happen to is frequent trips to the loo. Are you sure it's nothing else like milk, does all coffee affect you, does decaff take longer etc..
    – EdChum
    Jan 28, 2015 at 15:23
  • 1
    It does not affect everyone. While personally I am "immune" to this and always was, I know quite a few others who are not, so this is a worthy question. Jan 28, 2015 at 15:57
  • 1
    Related: biology.stackexchange.com/questions/1655/… (only says "Caffeine is not the active agent then, but some other compound in coffee" though) Jan 28, 2015 at 16:11
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    Actually it's all good, I was about to just quote the accepted answer there as answer here then realized what you ask is different. You don't ask "Does coffee have a laxative effect", so this is whole new question. That said, I now wonder if something is wrong with me as coffee got no effect on me in this aspect. :-D Jan 28, 2015 at 16:18

1 Answer 1


Disclaimer: I am not a doctor, nor do I play one on TV...

I would guess that it is a combination of a few factors.

  1. Coffee contains caffeine which is a stimulant and most stimulants have some degree of laxative effect.

    • If nothing else stimulants will raise your metabolism, so even if it isn't immediate you'll be heading to the bathroom sooner than you would without them.

    • It also looks like caffeine causes stimulation of the bowels specifically.

      coffee can also cause looser stools because increased peristalsis leaves less time for the colon to perform one of its key functions–reabsorbing water from fecal matter to produce well-formed stools. Be aware, however, that other common accompaniments to coffee can be culprits in this matter. Dairy products, excess sugar, even “sugarless” sweeteners like sorbitol (a well-known substance used as a laxative) can cause diarrhea. - Source

  2. Coffee is mostly water

    • Just drinking a couple full glasses of water on an empty stomach can lead to a softer stool.
  3. The psychological effect

    • I don't know if there have been any real studies on this, but I strongly suspect that there is some Classical Conditioning going on. Much like Pavlov's dogs who were conditioned to salivate at the sound of a bell, if your usual morning routine is to have a cup of coffee and then head to the restroom, over time you end up conditioning your self to do this regardless of whether or not the coffee is really "making you poop".
  • To point 2: I'm talking about one cup of coffee (will update question right after this). To point 3: I do drink that one cup of coffee at the same time (but also not every day, only from WE-FR) but I don't go to the toilet the same time after. I go when I feel like. Sometimes it's 5 mins, sometimes 1 hour. So I would say, for me personally, it's not affected of some kind of routine.
    – Alex
    Jan 28, 2015 at 16:24
  • @Alex They're are a lot of factors to consider when it comes to digestion... What ever your intake was up to 24hrs, or so before can have an effect on your output and these factors will be different from person to person.
    – apaul
    Jan 28, 2015 at 16:43
  • @Alex If your looking for what effects your system specifically, try to isolate different factors and run a few experiments. For instance try a caffeine tablet and see if it has the same effect or if you take milk or cream in your coffee try drinking them alone and see what happens.
    – apaul
    Jan 28, 2015 at 16:46
  • Yeah, I know. Juat wanted to let you know I get the laxative effect regardless of amount of coffee or daily routines. I could do those experiments, but it doesn't sound like a fun/tasty thing to do nor will it look usual to my office mates :P
    – Alex
    Jan 28, 2015 at 16:57

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