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Does coffee dehydrate you? Debunking this common misconception

Understanding coffee's effects

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Every coffee drinker has reached a point where they realize they’ve consumed about three or four cups of coffee and almost no water in a day. At this point, the notion that coffee dehydrates you may run through your head, reminding you to grab a glass of water. While drinking enough water is critical regardless of coffee consumption, the concept that coffee dehydrates you is not entirely true.

The misconception stems from the idea that coffee is a diuretic, which is true. However, are these diuretic effects enough to cause symptoms of dehydration? In this guide, we’ll break down everything you need to know about the question, “Does coffee dehydrate you?” Is this common belief made up, or is there some truth to it? Let’s explore.

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Does coffee dehydrate you?

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While coffee is a diuretic, that doesn’t necessarily mean it dehydrates you. Coffee’s caffeine content increases the amount of urine your body produces, which can increase the amount of fluids you lose. This process creates a mild diuretic effect, helping your kidneys to draw out extra salt and water. However, coffee is made of nearly 95% to 98% water, so the diuretic effects are mild. All in all, this means that the short answer is no, coffee does not dehydrate you.

Developing a tolerance

Man drinking coffee while working on a laptop
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The question “Does coffee dehydrate you?” also goes hand in hand with a few other key points. Most people who regularly consume coffee also begin to develop a tolerance. Habitual coffee consumption causes your body to adapt to regular coffee consumption, further impacting the diuretic effects of coffee. Over time, your body will adjust its fluid regulation mechanisms to reduce the amount of sodium and water lost. Studies have examined these effects, too, concluding that regular coffee drinkers experience little to no diuretic impact.

A study of 50 men who regularly drank coffee divided participants into a water-only group and those who drank both water and coffee. Overall, the researchers found almost no difference between the two groups. While this doesn’t mean you should completely disregard the idea that coffee could dehydrate you, it means you shouldn’t have much to worry about if you have just one or two cups daily.

Drinking too much coffee

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All in all, the casual coffee drinker is unlikely to drink enough coffee to become dehydrated. The FDA recommends that adults consume no more than 400 milligrams of caffeine daily. On average, a regular cup of coffee contains about 95 mg of caffeine (per 8 ounces), so it would take quite a few cups of coffee to reach the 400 mg limit.

However, many other coffee drinks, such as nitro cold brew or espresso drinks, can contain upwards of 200 mg per cup. At national coffee chains like Starbucks, extra-large sizes like venti sizes of some drinks can include even more than 200 mg of cup. With this in mind, it’s easy to see how you could accidentally consume too much caffeine daily.

As long as you stay under this limit, your coffee consumption will not likely cause dehydration symptoms. However, if you’re consuming more caffeine than you think, you could be at risk for symptoms of dehydration. Some signs and symptoms of dehydration include fatigue, confusion, dizziness, and headaches. You might also notice excessive thirst, dry mouth or lips, or dark-colored urine. Always see a doctor if you notice any signs of dehydration.

Suppose you think you’re about to consume 400 mg of caffeine (or are starting to develop symptoms of dehydration). In that case, switching to decaf or limiting caffeine consumption may be worthwhile to avoid dehydration.

How to avoid coffee’s diuretic effects

Cold brew coffee
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The best way to avoid experiencing coffee’s diuretic effects is to limit your consumption to one to three cups daily. However, this can be challenging for those with busy schedules or who love sipping delicious coffee all day. While switching to decaf is an option, some coffee lovers say the decaffeination process may impact the flavor. In these cases, switching to half caff coffee is a great idea to allow you to enjoy the taste of coffee you love with a lower caffeine content. You can also adjust the type of coffee you drink, as some coffee, such as light roast, may contain more caffeine than dark roast coffee.

If you reach for (another) coffee, it might be time to space your caffeine throughout the day and consume water in between. If you use coffee as a pre-workout for an energy boost, drink plenty of regular water throughout your workout.

Emily Caldwell
Emily is an accomplished freelance journalist focusing on food, beverage, health, fitness, and travel content. She loves to…
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