Does caffeine make you pee more?

September 11, 2017 4 min read

Does caffeine make you pee more?

Caffeine does make people urinate more if they aren't used to consuming it. Otherwise, caffeinated beverages may actually contribute to hydration. (Jorge Royan photo/Creative Commons)

Does caffeine make you pee more? There is sort of a debate going on as to whether caffeine makes you urinate too much or not. Some people say caffeine is a diuretic that makes you go to the bathroom too much and become hydrated. Others say the water in coffee and tea can even help to hydrate you, not dehydrate you.

But if you have six cups of coffee in one morning, obviously you are getting so much fluid that you are going to have to go to the bathroom more. Also, some studies have found that if you take a large amount of caffeine even in non-beverage form it can make you urinate more. Similarly, even a moderate amount of caffeine can make a person who is not used to caffeine urinate excessively.

The research

An article at WebMD.com states about the research:

Some research has shown that caffeine intake can also affect our fluid balance. In one study, 12 caffeine consumers were told to abstain from caffeine for five days and were then given 642 mg of caffeine in the form of coffee. Their urine output increased when given the caffeine. Another study done on eight men tested the effect of 45 mg, 90 mg, 180 mg, or 360 mg of caffeine on urine volume. An increase in urine volume was seen only at the 360 mg dose of caffeine. One limitation to these studies is that they did not evaluate the impact of caffeine when consumed on a regular basis. A onetime dose may affect the body differently than daily consumption.

Back in 1928, caffeine was shown to have no significant impact on urinary output. Subsequent studies have shown that caffeine-containing beverages did not impact urinary output any differently than other beverages. Based on this, the Institute of Medicine recommends that ‘unless additional evidence becomes available indicating cumulative total water deficits in individuals with habitual intakes of significant amounts of caffeine, caffeinated beverages appear to contribute to the daily total water intake similar to that contributed by noncaffeinated beverages.’

You can hydrate by drinking caffeinated beverages

In other words, you can actually hydrate yourself by drinking coffee, tea or soda, though plain water is still recommended as the best way to get your daily fluids.

But WebMD says caffeine can increase the need to pee. It can depend on how much caffeine you take, your tolerance for it and the type of food, drink or medicine you get it in. And if you have urinary incontinence or have frequent urges to urinate, it may increase after drinking a caffeinated beverage.

Facts and myths

Caffeine Informer, a site that features many articles about the facts and myths surrounding caffeine, has an article titled Caffeine and Hydration: What the Research Says.

This article too cites the study that said caffeine can act as a diuretic that promotes urination, but only in doses of 360 mg or more and the second study that found that if you have built up a tolerance, the effect is less noticeable. Those who have little to no tolerance built up to caffeine may experience significant diuretic effects. (There are references to these studies in the Caffeine Informer article.)

"Yet another study found that consuming caffeine prior to exercise negated the diuretic effect of caffeine as compared to consuming caffeine and then resting," Caffeine Informer writes.

Caffeine vs. taurine

But Caffeine Informer cited another study that considered energy-drink consumption and how caffeine vs. taurine affected hydration. The study found that the subjects that drank caffeinated energy drink peed a lot more than the group that got just taurine in the drinks. They were already dehydrated, too.

"Therefore, based on the research, caffeine is a diuretic but not a very efficient one since there are several factors that determine how well it actually works in this capacity," the article states.

The article asks, Then why does coffee make me have to pee?

There are possibly a couple of reasons for this. Firstly, if you are already in a hydrated state any additional fluids will cause increased urine production. So, a 12-16 fl oz (355-500 ml) coffee will produce about the same amount of urine output.

Secondly, if you aren't a regular coffee or caffeine consumer then large amounts of caffeine does have a diuretic or dehydrating effect, thus increasing urine volume.

Lastly, caffeine can cause incontinence in some men and women. This causes the urge to urinate even if the bladder isn't yet full.

Does caffeine make you pee more?

In an article exploring whether caffeine causes dehydration, Livestrong.com asked Lawrence Armstrong of the Department of Kinesiology at the University of Connecticut and the director of the Human Performance Laboratory whether caffeine dehydrates people. He said:

'˜The truth of the matter is, a small increase in urine output has little to do with dehydrating the body. If you drink a liter of water, [urination] will increase. Doesn't mean you shouldn't drink water.

˜The fact that we don't have hospital emergency rooms filled [with patients] because they [drank] caffeinated beverages is clear evidence ... If there were negative health effects, [they] certainly would have been identified.'

University of Connecticut researcher and author of a study on diuresis and caffeine Sophie Killer told National Public Radio: "It's well understood that if you drink coffee habitually you can develop a tolerance to the potential diuretic effects of coffee.”

By the way, that NPR article says: "Bottom line: A daily coffee habit won't lead to dehydration. But it's best to limit caffeine to moderate levels to steer clear of jitters and interruptions to sleep."

Go ahead and enjoy your caffeinated beverage, chocolate, mint, kola nuts or medicine. But if you haven't built up a tolerance for caffeine, expect to urinate more. And if you have more than 360 mg, expect to pee more even if you have built up a tolerance.
Mark Miller
Mark Miller



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