# Question about caffeine dehydration--can one just drink more water? **URL:** \ **Category:** Factual Questions\ **Created:** [January 5, 2010, 1:46pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740 "2010-01-05T13:46:57Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [January 5, 2010, 1:46pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/1 "2010-01-05T13:46:57Z")
I read that caffeine dehydrates you. (Yes, I’m just learning this. 😉 ) Can this be adjusted for by drinking more water? Or does caffeine somehow prevent the body from taking in water, such that simply drinking more water won’t have the expected hydrating effect? ---
**Author:** ![Brown\_Eyed\_Girl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brown_eyed_girl/32/3574_2.png) [@Brown\_Eyed\_Girl](https://boards.straightdope.com/u/Brown_Eyed_Girl)\ **Post date:** [January 5, 2010, 1:50pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/2 "2010-01-05T13:50:51Z")
Caffeine is a diuretic, which means it makes you pee more. Peeing a lot without drinking a lot of fluids can have a dehydrating effect. Fortunately, coffee is 98% water. Wrt dehydration, you should be okay taking in the amount of caffeine present in coffee that is dissolved in water. Drink water or some other type of liquid with your chocolate, though, and don’t worry about it. ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [January 5, 2010, 2:44pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/3 "2010-01-05T14:44:31Z")
There is certainly a finite amount of caffeine you should have in your system. It contracts your cells, reducing their water capacity - forcing them into a dehydrated state - meaning they won’t rehydrate until the caffeine disperses. So it doesn’t matter how much water you drink if you have too much caffeine in your system. It will just pass right through. ---
**Author:** ![butler1850](https://avatars.discourse-cdn.com/v4/letter/b/779978/32.png) [@butler1850](https://boards.straightdope.com/u/butler1850)\ **Post date:** [January 5, 2010, 3:14pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/4 "2010-01-05T15:14:46Z")
**Pan1** , I’d imagine that level has to be pretty high. If you’re so caffeinated that you’re in an irreversible dehydration state, you’d be wired near to explosion levels. \*\*Frylock, \*\*Drink the water, you’ll be fine. Everyone needs to drink a bit more water anyway. And if you don’t need it, your body will get rid of it. ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [January 5, 2010, 3:26pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/5 "2010-01-05T15:26:51Z")
Or…you could not worry about it, since it’s a myth, anyway: [http://www.beverageinstitute.org/healthcare\_professionals/caffeine\_qa.shtml](http://www.beverageinstitute.org/healthcare_professionals/caffeine_qa.shtml) [http://www.divinecaroline.com/22178/46361-coffee-makes-dehydrated--say-what-](http://www.divinecaroline.com/22178/46361-coffee-makes-dehydrated--say-what-) > **[Do You Need Eight Glasses of Water Per Day?](https://www.snopes.com/fact-check/water-works-2/)** > > Rumor: The average person needs to drink eight glasses of water per day to avoid being 'chronically dehydrated.' [http://www.artofdrink.com/2009/12/caffeine-in-coffee-does-not-increase-dehydration-during-hangovers.php](http://www.artofdrink.com/2009/12/caffeine-in-coffee-does-not-increase-dehydration-during-hangovers.php) ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [January 5, 2010, 3:37pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/6 "2010-01-05T15:37:38Z")
> [@TimeWinder](#): > > Or…you could not worry about it, since it’s a myth, anyway: > > [http://www.beverageinstitute.org/healthcare\_professionals/caffeine\_qa.shtml](http://www.beverageinstitute.org/healthcare_professionals/caffeine_qa.shtml) > [Registered & Protected by MarkMonitor](http://www.divinecaroline.com/22178/46361-coffee-makes-dehydrated--say-what-) > [Do You Need Eight Glasses of Water Per Day? | Snopes.com](http://www.snopes.com/medical/myths/8glasses.asp) > [http://www.artofdrink.com/2009/12/caffeine-in-coffee-does-not-increase-dehydration-during-hangovers.php](http://www.artofdrink.com/2009/12/caffeine-in-coffee-does-not-increase-dehydration-during-hangovers.php) To call it a myth is a bit blaise. Caffeine does dehydrate, but no one really drinks enough to have a noticable effect. Of course, with all the energy shots/red bull type drinks out there now, it might be possible to do so. I don’t know how much that top cite is worth since it’s sponsored by CocaCola. The information seems valid, but the source of the information should be looked upon with skepticism. ---
**Author:** ![Brown\_Eyed\_Girl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brown_eyed_girl/32/3574_2.png) [@Brown\_Eyed\_Girl](https://boards.straightdope.com/u/Brown_Eyed_Girl)\ **Post date:** [January 5, 2010, 5:47pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/7 "2010-01-05T17:47:00Z")
> [@pan1](#): > > To call it a myth is a bit blaise. > > Caffeine does dehydrate, but no one really drinks enough to have a noticable effect. Of course, with all the energy shots/red bull type drinks out there now, it might be possible to do so. > > I don’t know how much that top cite is worth since it’s sponsored by CocaCola. The information seems valid, but the source of the information should be looked upon with skepticism. What’s enough? Warning: anecdote time. When I worked at Starbuck I’d have upwards of 12 shots of fully caffeinated espresso pretty much daily (or at least every day I worked). I never found myself dehydrated. The thing to note is that my caffeine was always suspended in fluid. On rare occasions, however, I have over-caffeinated myself to the point suffering from the shakes and getting hot flashes, but that’s abuse of a stimulant, not dehydration. What’s interesting is that most people were so fearful of my intake, I asked my doctor about it. What he told me, after asking numerous questions about my health, is that I’ve likely built up a tolerance to the drug and that I’d likely suffer ill-effects if I adjusted my regular dosage of caffeine, but that it wasn’t causing me any problems at the moment. Long term, I believe he indicated I might want to reevaluate my caffeine intake and then he told me to watch my (normal) blood pressure for cues. The second link of TimeWinder’s list mentions caffeine tolerance with regard to electrolyte/fluid balance: > [@](#): > > In his review, “Caffeine, Body Fluid-Electrolyte Balance, and Exercise Performance,” Lawrence E. Armstrong, a professor of exercise physiology at the University of Connecticut disproves the notion that caffeinated beverages rob us of our precious fluids. By reviewing the scientific research on the subject, he concludes that although caffeine, like water, is a mild diuresis (it increases excretion of urine), moderate caffeine consumption does not produce a “fluid-electrolyte imbalance” that can affect health or exercise performance. Furthermore, we retain roughly the same amount of fluid after drinking a caffeinated beverage as we do after drinking water. > > Even more encouraging for habitual coffee consumers is the finding that those with caffeine tolerance have reduced likelihood that a fluid electrolyte imbalance will occur. The more regular your caffeine habit, the more fluid your body is conditioned to retain. Now, my intake is considerably less, my BP is still normal, and I’m still just an anecdote, but at least Divine Caroline backs me up. 🙂 ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [January 5, 2010, 6:59pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/8 "2010-01-05T18:59:34Z")
> [@pan1](#): > > I don’t know how much that top cite is worth since it’s sponsored by CocaCola. The information seems valid, but the source of the information should be looked upon with skepticism. Which is why I gave you four cites, including two (indirectly referenced) scientific studies and Snopes. If you’d like a couple hundred more, you can enter “caffeine dehydrate” into Bing or Google. If drinking a caffeinated beverage does not result in a net water loss, it’s not dehydrating. And the actual studies don’t even detect a difference in water output from caffienated beverages, much less a difference that would overcome the quantity of the liquid carrying the caffeine. It’s a myth. Really. If you still don’t believe me, drink eight glasses of water today and measure your urine output. Drink eight glasses of caffeinated pop tomorrow and measure. It’s not the most pleasant experiment in the world, but it’s trivially easy to show that the supposed effect is false. Don’t want to do that? Just drink purely caffeinated beverages (no water or other beverages) for a week and notice that you aren’t dead (3 days without water would be enough to seriously injure or kill you). You won’t sleep much, but your water level will be fine. ---
**Author:** ![Obsidian](https://avatars.discourse-cdn.com/v4/letter/o/51bf81/32.png) [@Obsidian](https://boards.straightdope.com/u/Obsidian)\ **Post date:** [January 5, 2010, 7:30pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/9 "2010-01-05T19:30:09Z")
Years ago I took a flu-having friend to urgent care, and the nurse asked her if she’d been drinking liquids, then asked what kind. When she answered “tea” the nurse said that it doesn’t count because it’s caffeinated, that the caffeine completely negated the water, and she needed 8-10 glasses of water on top of the tea. This woman was _adamant_ that caffeinated beverages provided no hydration whatsoever. My friend replied all she drank was tea, and if that was the case she hadn’t had anything to drink in months and should be dead. **Timewinder** , I kind of despise plain water and there’s too much sugar in juice. Like my friend I drink tea (iced or hot), and the occasional diet coke. I sleep fine, as I’m accustomed. ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [January 5, 2010, 8:06pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/10 "2010-01-05T20:06:51Z")
> [@TimeWinder](#): > > Don’t want to do that? Just drink purely caffeinated beverages (no water or other beverages) for a week and notice that you aren’t dead (3 days without water would be enough to seriously injure or kill you). You won’t sleep much, but your water level will be fine. I drink nothing but Coke Zero. Plain water - rarely, not daily. I’m not disagreeing with the fact that normal caffeine intake and even above normal caffeine intake will not dehydrate you. But it’s not a myth that caffeine dehydrates. It just doesn’t do so at a level we’d notice at usual and unusual consumption levels. The flaw here, I think, is that what you are saying is a myth is not what I am saying is not. It’s not a myth that caffeine dehydrates. It is a myth that coffee/coke dehydrates more than it hydrates. Honestly by the time you intake enough caffeine to cause hydration problems, other problems will be more prominent. For what it matters, when engaging in a factual argument, don’t even mention a questionable source of facts - right or wrong, the integrity of the potential biased source hinders the integrity of all of your arguments. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [January 5, 2010, 8:53pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/11 "2010-01-05T20:53:59Z")
> [@Frylock](#): > > I read that caffeine dehydrates you. Can this be adjusted for by drinking more water? On a bit of a tangent here, but, _anything_ that dehydrates you, whether a medicine, alcohol, caffeine, or whatever, _always_ causes you to pee out salt and water, not just water. It is physiologically impossible for a person to pee out salt-free water, no matter if you’re referring to normal peeing or peeing in disease states. So, by definition, water alone is never adequate to replace urine losses. Notwithstanding the above, in most cases, you’ll do just fine by drinking pure, salt-free water to replace urinary losses since the amount of salt lost is small. However, in cases of large and ongoing diuresis (excessive peeing), there is signicant salt loss accompanying the water loss in the urine. In such instances, taking in salt-free water alone is inadequate - you must also take some salt. If you don’t, [hyponatremia](http://en.wikipedia.org/wiki/Hyponatremia), a potentially serious state can result. The same rationale applies to extreme sweating as well. That’s why Gatorade is so popular among athletes - it contains salt. (in this post, salt = sodium) ---
**Author:** ![Brown\_Eyed\_Girl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brown_eyed_girl/32/3574_2.png) [@Brown\_Eyed\_Girl](https://boards.straightdope.com/u/Brown_Eyed_Girl)\ **Post date:** [January 5, 2010, 10:35pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/12 "2010-01-05T22:35:50Z")
> [@pan1](#): > > The flaw here, I think, is that what you are saying is a myth is not what I am saying is not. It’s not a myth that caffeine dehydrates. It is a myth that coffee/coke dehydrates more than it hydrates. Honestly by the time you intake enough caffeine to cause hydration problems, other problems will be more prominent. > > For what it matters, when engaging in a factual argument, don’t even mention a questionable source of facts - right or wrong, the integrity of the potential biased source hinders the integrity of all of your arguments. Here are [two](http://www.ncbi.nlm.nih.gov/pubmed/19774754) [studies](http://www.sportsnutritionworkshop.com/Files/32.SPNT.pdf) [warning: PDF] that disagree with you. From the first link: > [@](#): > > CONCLUSION: The most ecologically valid of the published studies offers **no support for the suggestion that consumption of caffeine-containing beverages as part of a normal lifestyle leads to fluid loss in excess of the volume ingested or is associated with poor hydration status**. Therefore, there would appear to be no clear basis for refraining from caffeine containing drinks in situations where fluid balance might be compromised. I bolded the relevant part. How about you pony up some cites for your assertion? I can’t find anything that indicates dehydration at the cellular level due to caffeine other than a bunch of natural health sites. [Here’s something else](http://en.wikipedia.org/wiki/Chronic_cellular_dehydration) I found out about “chronic cellular dehydration.” It’s a marketing term. ---
**Author:** ![Irishman](https://avatars.discourse-cdn.com/v4/letter/i/b487fb/32.png) [@Irishman](https://boards.straightdope.com/u/Irishman)\ **Post date:** [January 5, 2010, 11:14pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/13 "2010-01-05T23:14:29Z")
That interview may be hosted on a potentially biased site, but the article is fully cited. The interviewee is the author of one of the studies that is cited by the snopes article. ---
**Author:** ![TimeWinder](https://avatars.discourse-cdn.com/v4/letter/t/bcef8e/32.png) [@TimeWinder](https://boards.straightdope.com/u/TimeWinder)\ **Post date:** [January 5, 2010, 11:50pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/14 "2010-01-05T23:50:15Z")
> [@Brown\_Eyed\_Girl](#): > > I bolded the relevant part. How about you pony up some cites for your assertion? In fairness, I think **pan1** is agreeing with you (and me) that there’s no _net loss_ of water. We’re quibbling over the definition of “dehydration.” I’d claim that if you drink something, and you end up with more total water in your system than before, that it did not “dehydrate” you. **pan1** is using the definition that drinking water + caffeine will result in you retaining _less_ water than if you’d just drunk the water alone, and calling that “dehydration.” These are not the same use of “dehydration,” and both arguments could be correct given their respective definitions. That said, the studies I looked at indicated they couldn’t find any effect at all, not even by **pan1** ’s much looser standard of dehydration. ---
**Author:** ![Brown\_Eyed\_Girl](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brown_eyed_girl/32/3574_2.png) [@Brown\_Eyed\_Girl](https://boards.straightdope.com/u/Brown_Eyed_Girl)\ **Post date:** [January 6, 2010, 12:44am UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/15 "2010-01-06T00:44:48Z")
> [@TimeWinder](#): > > In fairness, I think **pan1** is agreeing with you (and me) that there’s no _net loss_ of water. We’re quibbling over the definition of “dehydration.” If so, it was unclear when he said: [QUOTE=pan1] It’s not a myth that caffeine dehydrates. [/QUOTE] The studies linked to indicate that it is most certainly \*is \*a myth. [QUOTE=TimeWinder] pan1 is using the definition that drinking water + caffeine will result in you retaining less water than if you’d just drunk the water alone, and calling that “dehydration.” [/QUOTE] Well, where does the fluid go then? If you take in something, you have to expel it if you aren’t going to retain it. That’s what a diuretic does. The studies are clear on this. Once again from the first study: > [@](#): > > The available literature suggests that acute ingestion of caffeine in large doses (at least 250-300 mg, equivalent to the amount found in 2-3 cups of coffee or 5-8 cups of tea) results in a short-term stimulation of urine output in individuals who have been deprived of caffeine for a period of days or weeks. A profound tolerance to the diuretic and other effects of caffeine develops, however, and the actions are much diminished in individuals who regularly consume tea or coffee. Doses of caffeine equivalent to the amount normally found in standard servings of tea, coffee and carbonated soft drinks appear to have no diuretic action. Caffeine is a mild diuretic in moderate to large doses for those who have not had caffeine in their system for awhile. Not so for regular coffee drinkers and those who drink caffeinated soda, tea, and a single cup of coffee. What **pan1** is claiming: that caffeine causes “cellular dehydration” is also a myth, as well. I’m pretty sure that the SOP around here is provide cites. Especially if you’re going to criticize those cites and then contradict them. I hope **pan1** is so inclined. ---
**Author:** ![pan1](https://avatars.discourse-cdn.com/v4/letter/p/e495f1/32.png) [@pan1](https://boards.straightdope.com/u/pan1)\ **Post date:** [January 6, 2010, 4:40pm UTC](https://boards.straightdope.com/t/question-about-caffeine-dehydration-can-one-just-drink-more-water/523740/16 "2010-01-06T16:40:35Z")
> [@Brown\_Eyed\_Girl](#): > > What **pan1** is claiming: that caffeine causes “cellular dehydration” is also a myth, as well. The problem with knowing everything I know off the top of my head is that citation becomes problematic - especially when what I know is actually incorrect. Now I have to go lay the smackdown on my old friends who used the cellular dehydration theory when explaining why its bad that the only water I intake comes in my foods and my Coca-Cola.