Table of ContentsView AllTable of ContentsDiuretic EffectsWater Content in CoffeeStopping Diuretic EffectsIs Tea More Hydrating?How to Tell If You’re Dehydrated

Table of ContentsView All

View All

Table of Contents

Diuretic Effects

Water Content in Coffee

Stopping Diuretic Effects

Is Tea More Hydrating?

How to Tell If You’re Dehydrated

It’s a widely held belief that coffee has dehydrating effects. Butdoescoffee dehydrate you? Probably not. Studies show that it’s unlikely for moderate coffee consumption to lead to dehydration.

Coffee’s reputation for causing dehydration may stem from its mild diuretic effects or the dry mouth many coffee drinkers experience after their morning cup of joe.

This article explores the science behind coffee’s diuretic effects and its impact on your body’s hydration levels. It also explains why you might feel thirsty after drinking coffee and how to tell if you’re dehydrated.

Oleg Breslavtsev / Getty Images

Close up shot of a person sitting at a cafe table, holding a coffee beverage with latte art.

Caffeine, Dehydration, and Diuretic Effects

Research suggests that, for habitual coffee drinkers, coffee is just as hydrating aswater.It takes the body between one and four days to build a tolerance to the effects of caffeine, including its diuretic effect. So, regular coffee drinkers are less likely to experience increased urine output than those who drink the occasional cup of coffee.

That doesn’t necessarily mean you should reach for a caffeinated beverage whenever you feel thirsty. When it comes to caffeine consumption, moderation is key.

Consuming four or more cups of coffee daily—or more than 400 milligrams (mg) of caffeine—increases urine output for habitual and casual coffee drinkers, which may be mildly dehydrating. Research findings show that coffee containing high amounts of caffeine increases urine output (within two to three hours after ingestion) more than coffee containing lower amounts.

Why Am I So Dehydrated? 9 Common Reasons

How Much Water Is in Coffee?

Coffee is mostly water. The water content in a cup of coffee can vary depending on the coffee bean type, degree of roast (light vs. dark), brewing method, and the coffee-to-water ratio.For example, a shot of espresso contains less water than drip coffee, and light-roast coffee beans tend to have higher concentrations of caffeine than dark-roast beans.

On average, water accounts for 98% of the total volume of the standard 6-ounce cup of brewed coffee. This means a 6-ounce cup of coffee contains about 5.88 ounces of water.Although coffee can contribute to your daily fluid intake, plain water is still your best bet for staying hydrated.

Why Does Coffee Cause Dry Mouth?Contrary to popular belief, dry mouth after drinking coffee isn’t due to dehydration. Coffee contains tannins—compounds responsible for coffee’s bitter flavor and dry mouth effects. Tannins bind to proteins in saliva, making it thicker and less effective at lubricating your mouth, leading to a dry mouth sensation.

Why Does Coffee Cause Dry Mouth?

Contrary to popular belief, dry mouth after drinking coffee isn’t due to dehydration. Coffee contains tannins—compounds responsible for coffee’s bitter flavor and dry mouth effects. Tannins bind to proteins in saliva, making it thicker and less effective at lubricating your mouth, leading to a dry mouth sensation.

Can You Stop Coffee’s Diuretic Effects?

If you’re a regular coffee drinker and limit your intake to less than 400 mg of caffeine daily, coffee likely won’t dehydrate you. But if you drink a lot of coffee and are concerned about hydration, you can offset any fluid loss and stay hydrated. Here’s how:

Compared to Coffee, Is Tea More Hydrating?

Compared to coffee, tea is generally considered to be more hydrating because it contains less caffeine. Caffeine amounts in tea vary, depending on the type of tea, brewing method, and steeping time. Here’s a breakdown of caffeine content per 8-ounce serving of coffee and tea:

Dehydrationoccurs when your body loses more fluids than you consume.Signs and symptoms of dehydrationinclude:

Causes of DehydrationCoffee isn’t likely to dehydrate you. However, factors that cause the body to lose fluids more quickly than you can replace them might. Common causes of dehydration include:Excessive sweatingVomitingDiarrheaNot drinking enough fluidsFrequent urination (usually due to certain illnesses or medications)

Causes of Dehydration

Coffee isn’t likely to dehydrate you. However, factors that cause the body to lose fluids more quickly than you can replace them might. Common causes of dehydration include:Excessive sweatingVomitingDiarrheaNot drinking enough fluidsFrequent urination (usually due to certain illnesses or medications)

Coffee isn’t likely to dehydrate you. However, factors that cause the body to lose fluids more quickly than you can replace them might. Common causes of dehydration include:

Summary

Coffee contains caffeine, a stimulant with mild diuretic effects. You might notice you are peeing more frequently after drinking coffee, but the amount of fluid lost through urination is not enough to cause dehydration.

Most people can safely enjoy coffee without having to worry about dehydration. Drinking more than four cups daily may increase the risk of mild dehydration. Drinking plenty of water throughout the day can mitigate the effects of caffeine and ensure you can enjoy your coffee beverages and stay hydrated.

If you are sensitive to the effects of caffeine and concerned about your hydration levels, consider drinking decaf coffee or tea, which is lower in caffeine and less likely to cause diuretic effects.

13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Killer SC, Blannin AK, Jeukendrup AE.No evidence of dehydration with moderate daily coffee intake: A counterbalanced cross-over study in a free-living population.PLoS One. 2014;9(1):e84154. doi:10.1371/journal.pone.0084154Schwartz M, Neiers F, Feron G, Canon F.The relationship between salivary redox, diet and food flavor perception.Front Nutr. 2021;7:612735. doi:10.3389/fnut.2020.612735Cappelletti S, Piacentino D, Sani G, Aromatario M.Caffeine: Cognitive and physical performance enhancer or psychoactive drug?2015;13(4):554.Curr Neuropharmacol. 2015;13(1):71-88. doi:10.2174/1570159X13666141210215655Zhang Y, Coca A, Casa DJ, et al.Caffeine and diuresis during rest and exercise: A meta-analysis.J Sci Med Sport. 2015;18(5):569-574. doi:10.1016/j.jsams.2014.07.017Zhang S, Takano J, Murayama N, et al.Subacute ingestion of caffeine and oolong tea increases fat oxidation without affecting energy expenditure and sleep architecture: A randomized, placebo-controlled, double-blinded cross-over trial.Nutrients. 2020;12(12):3671. doi:10.3390/nu12123671Seal AD, Bardis CN, Gavrieli A, et al.Coffee with high but not low caffeine content augments fluid and electrolyte excretion at rest.Front Nutr. 2017;4:40. doi:10.3389/fnut.2017.000Olechno E, Puścion-Jakubik A, Zujko ME, et al.Influence of various factors on caffeine content in coffee brews.Foods. 2021;10(6):1208.doi:10.3390/foods10061208Harvard T.H. Chan School of Public Health: The Nutrition Source.Coffee.Starbucks Corporation.Starbucks coffee expert shares secrets for brewing coffee at home.Soares S, Brandão E, Guerreiro C, et al.Tannins in food: Insights into the molecular perception of astringency and bitter taste.Molecules. 2020;25(11):2590. doi:10.3390/molecules25112590Centers for Disease Control and Prevention.About water and healthier drinks.Academy of Nutrition and Dietetics.The health benefits of tea.MedlinePlus.Dehydration.

13 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Killer SC, Blannin AK, Jeukendrup AE.No evidence of dehydration with moderate daily coffee intake: A counterbalanced cross-over study in a free-living population.PLoS One. 2014;9(1):e84154. doi:10.1371/journal.pone.0084154Schwartz M, Neiers F, Feron G, Canon F.The relationship between salivary redox, diet and food flavor perception.Front Nutr. 2021;7:612735. doi:10.3389/fnut.2020.612735Cappelletti S, Piacentino D, Sani G, Aromatario M.Caffeine: Cognitive and physical performance enhancer or psychoactive drug?2015;13(4):554.Curr Neuropharmacol. 2015;13(1):71-88. doi:10.2174/1570159X13666141210215655Zhang Y, Coca A, Casa DJ, et al.Caffeine and diuresis during rest and exercise: A meta-analysis.J Sci Med Sport. 2015;18(5):569-574. doi:10.1016/j.jsams.2014.07.017Zhang S, Takano J, Murayama N, et al.Subacute ingestion of caffeine and oolong tea increases fat oxidation without affecting energy expenditure and sleep architecture: A randomized, placebo-controlled, double-blinded cross-over trial.Nutrients. 2020;12(12):3671. doi:10.3390/nu12123671Seal AD, Bardis CN, Gavrieli A, et al.Coffee with high but not low caffeine content augments fluid and electrolyte excretion at rest.Front Nutr. 2017;4:40. doi:10.3389/fnut.2017.000Olechno E, Puścion-Jakubik A, Zujko ME, et al.Influence of various factors on caffeine content in coffee brews.Foods. 2021;10(6):1208.doi:10.3390/foods10061208Harvard T.H. Chan School of Public Health: The Nutrition Source.Coffee.Starbucks Corporation.Starbucks coffee expert shares secrets for brewing coffee at home.Soares S, Brandão E, Guerreiro C, et al.Tannins in food: Insights into the molecular perception of astringency and bitter taste.Molecules. 2020;25(11):2590. doi:10.3390/molecules25112590Centers for Disease Control and Prevention.About water and healthier drinks.Academy of Nutrition and Dietetics.The health benefits of tea.MedlinePlus.Dehydration.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Killer SC, Blannin AK, Jeukendrup AE.No evidence of dehydration with moderate daily coffee intake: A counterbalanced cross-over study in a free-living population.PLoS One. 2014;9(1):e84154. doi:10.1371/journal.pone.0084154Schwartz M, Neiers F, Feron G, Canon F.The relationship between salivary redox, diet and food flavor perception.Front Nutr. 2021;7:612735. doi:10.3389/fnut.2020.612735Cappelletti S, Piacentino D, Sani G, Aromatario M.Caffeine: Cognitive and physical performance enhancer or psychoactive drug?2015;13(4):554.Curr Neuropharmacol. 2015;13(1):71-88. doi:10.2174/1570159X13666141210215655Zhang Y, Coca A, Casa DJ, et al.Caffeine and diuresis during rest and exercise: A meta-analysis.J Sci Med Sport. 2015;18(5):569-574. doi:10.1016/j.jsams.2014.07.017Zhang S, Takano J, Murayama N, et al.Subacute ingestion of caffeine and oolong tea increases fat oxidation without affecting energy expenditure and sleep architecture: A randomized, placebo-controlled, double-blinded cross-over trial.Nutrients. 2020;12(12):3671. doi:10.3390/nu12123671Seal AD, Bardis CN, Gavrieli A, et al.Coffee with high but not low caffeine content augments fluid and electrolyte excretion at rest.Front Nutr. 2017;4:40. doi:10.3389/fnut.2017.000Olechno E, Puścion-Jakubik A, Zujko ME, et al.Influence of various factors on caffeine content in coffee brews.Foods. 2021;10(6):1208.doi:10.3390/foods10061208Harvard T.H. Chan School of Public Health: The Nutrition Source.Coffee.Starbucks Corporation.Starbucks coffee expert shares secrets for brewing coffee at home.Soares S, Brandão E, Guerreiro C, et al.Tannins in food: Insights into the molecular perception of astringency and bitter taste.Molecules. 2020;25(11):2590. doi:10.3390/molecules25112590Centers for Disease Control and Prevention.About water and healthier drinks.Academy of Nutrition and Dietetics.The health benefits of tea.MedlinePlus.Dehydration.

Killer SC, Blannin AK, Jeukendrup AE.No evidence of dehydration with moderate daily coffee intake: A counterbalanced cross-over study in a free-living population.PLoS One. 2014;9(1):e84154. doi:10.1371/journal.pone.0084154

Schwartz M, Neiers F, Feron G, Canon F.The relationship between salivary redox, diet and food flavor perception.Front Nutr. 2021;7:612735. doi:10.3389/fnut.2020.612735

Cappelletti S, Piacentino D, Sani G, Aromatario M.Caffeine: Cognitive and physical performance enhancer or psychoactive drug?2015;13(4):554.Curr Neuropharmacol. 2015;13(1):71-88. doi:10.2174/1570159X13666141210215655

Zhang Y, Coca A, Casa DJ, et al.Caffeine and diuresis during rest and exercise: A meta-analysis.J Sci Med Sport. 2015;18(5):569-574. doi:10.1016/j.jsams.2014.07.017

Zhang S, Takano J, Murayama N, et al.Subacute ingestion of caffeine and oolong tea increases fat oxidation without affecting energy expenditure and sleep architecture: A randomized, placebo-controlled, double-blinded cross-over trial.Nutrients. 2020;12(12):3671. doi:10.3390/nu12123671

Seal AD, Bardis CN, Gavrieli A, et al.Coffee with high but not low caffeine content augments fluid and electrolyte excretion at rest.Front Nutr. 2017;4:40. doi:10.3389/fnut.2017.000

Olechno E, Puścion-Jakubik A, Zujko ME, et al.Influence of various factors on caffeine content in coffee brews.Foods. 2021;10(6):1208.doi:10.3390/foods10061208

Harvard T.H. Chan School of Public Health: The Nutrition Source.Coffee.

Starbucks Corporation.Starbucks coffee expert shares secrets for brewing coffee at home.

Soares S, Brandão E, Guerreiro C, et al.Tannins in food: Insights into the molecular perception of astringency and bitter taste.Molecules. 2020;25(11):2590. doi:10.3390/molecules25112590

Centers for Disease Control and Prevention.About water and healthier drinks.

Academy of Nutrition and Dietetics.The health benefits of tea.

MedlinePlus.Dehydration.

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