Is Coffee a Diuretic?

Chad J. Smith

Coffee is typically considered a diuretic, at least from an official medical or dietary standpoint. A diuretic is any substance that stimulates urination in the body. Many of these sorts of compounds are synthetically created, usually for use in the treatment of certain specific conditions; some also occur naturally, as is the case where coffee is concerned. There isn’t usually anything about coffee itself that is intrinsically diuretic, except to the extent that it contains caffeine. Naturally occurring caffeine, be it in coffee beans, tea leaves, or elsewhere, typically has a mild diuretic effect. People who drink a lot of coffee often find themselves urinating more frequently than they would had they consumed only water. This more frequent flushing of the urine has some to believe that caffeine can dehydrate a person, though this isn’t usually accurate except in the cases of extreme or excessive consumption. Excessive caffeine consumption of any kind can also lead to a number of negative health consequences. Most experts recommend that coffee consumers drink plenty of water each day to maintain optimal health and avoid potential side effects.

The caffeine in coffee can serve as a diuretic.
The caffeine in coffee can serve as a diuretic.

Understanding Diuretics Generally

Diuretics are a class of chemicals that stimulate the production of urine, often forcing the kidneys to fill the bladder even when there isn’t otherwise a pressing need for fluid elimination. Caffeine is one of the most common examples of this compound in nature. In addition to promoting alertness and boosting energy, the chemicals in caffeine also trigger urine production. Coffee beans contain varying levels of caffeine, and this makes coffee a diuretic.

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People who drink coffee on a regular basis are less likely to notice its diuretic effects.
People who drink coffee on a regular basis are less likely to notice its diuretic effects.

Caffeine and Coffee

In general, the diuretic effect of coffee and other caffeinated beverages is fairly low. The amount of caffeine in a given cup of the beverage can also vary tremendously depending on things like how long the beans were allowed to grow before harvesting, how they were roasted, and how strongly they were brewed. It’s usually true that coffee contains more caffeine per cup than tea and soda, but not always.

Diuretics can affect blood pressure levels.
Diuretics can affect blood pressure levels.

Even the strongest cup is usually considered mild when it comes to its diuretic properties, though. Sometimes doctors and other medical care providers will prescribe strong pharmaceutical diuretic drugs to flush urine out of the body, usually as a means of preparing for some particular procedure or treating a certain condition. Caffeine isn’t usually strong enough to serve these sorts of purposes.

Coffee can cause those who drink it to urinate more frequently.
Coffee can cause those who drink it to urinate more frequently.

Primary Effects of Consumption

People usually drink coffee for the stimulant effects of caffeine, and the first thing most notice is an increased alertness and a feeling of being awake and focused. The diuretic effects are sometimes hard to notice at first, but they usually present as an increased need to urinate. People who don’t drink coffee often usually see the most noticeable effects, and often find themselves in the bathroom a lot more than they expect. The volume of urine produced is often more than normal, too.

Regular coffee consumption can cause a person’s body to acclimatize. Caffeine is a drug in its own right and the brain can become dependent on it, and people who consume it more or less every day often find that they increasingly need to drink more and more to get the same stimulant effects. The same is true when it comes to what makes coffee a diuretic. With time, the body usually responds less dramatically to regular caffeine or coffee intake, and the need to urinate will usually lessen as a result.

Dehydration Concerns

Underlying the questions about coffee’s diuretic properties is the concern that it may somehow be harmful, because one may actually become dehydrated as a result of drinking too much coffee and, thus, urinating too much. Researchers usually agree that a little coffee is not harmful, and the concern over dehydration is unfounded. In reality, it is probably the urgency with which one needs to relieve himself that causes the concern.

Caffeine is a stimulant that increases and expedites the need to use the restroom, but it doesn’t usually cause people to expel more urine from their systems than normal when viewed over the span of an entire day. A cup of coffee is mostly water, so the diuretic effects may be offset by the water being consumed in the process of drinking the coffee. With that said, drinking enough plain water every day is part of a healthy routine, and most experts recommend that people consume several glasses of plain, clean water each day.

Because coffee is a diuretic, a cup or two a day may aid in weight loss through the decrease of water weight.
Because coffee is a diuretic, a cup or two a day may aid in weight loss through the decrease of water weight.

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Discussion Comments


@burcidi-- That's exactly right. Coffee doesn't make the body produce more urine, it just makes urine leave the body faster. It does this by stimulating urination. So that is the reason why coffee doesn't really carry the risk of dehydration like the over-the-counter or prescription diuretics.

@fify-- That's a good question. One reason could be that the type of caffeine in coffee is different than the caffeine in tea. Plus there is just more caffeine in coffee. I can never have coffee at night for this reason, but can have black tea without having any trouble sleeping.

I'm not sure how accurate this is, but I've heard that this diuretic effect of coffee might also be caused, or at least increased by the oils in coffee. Different people might also react to it differently. For example, I don't really drink more water like you do when I have coffee. But coffee does stimulate bowel movements with me, which it may not do for other people.


Okay, so, coffee makes us urinate more, but it doesn't increase urine output? How does that work?

Does coffee just quicken urination? The amount of urine that would leave our body by, let's say, midnight, will leave by the afternoon?

Is this what this means? If it is, then coffee is not "diuretic" in the same sense that diuretic water pills are. I believe water pills actually increase urine output (not just quicken it) and they have a risk of dehydration.


I'm a big coffee drinker and I believe that coffee has health benefits. But coffee does make me go to the restroom more because it makes me drink more water.

I had no idea that coffee is diuretic and always wondered why I drink so much water after having coffee. For every one cup of coffee, I have an extra two glasses of water. It's this extra water that makes me go to the bathroom more.

If I didn't drink more water with coffee, I don't think I would go to the restroom more than usual. But I'd probably be dehydrated because it makes me so thirsty!

Black tea makes me thirsty too, but not as much as coffee does even though they both have caffeine. Does anyone know why?

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