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Is Coffee a Diuretic?
Updated on May 30, 2023
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Is Coffee a Diuretic?

In short: Yes. Drinking coffee—or at least ingesting the caffeine in coffee—does have a diuretic effect of making you urinate more, which can cause dehydration.

Caffeine is a natural diuretic, so if you drink coffee, especially in excess without drinking water, you do run the risk of dehydration.

Therefore, coffee is considered a mild diuretic if you consistently surpass the recommended threshold of 400 mg a day, or up to four cups of brewed coffee.1

Is Coffee a Diuretic? 2

What is a Diuretic?

Diuretics are most commonly known medically as “water pills”—a kind of medicine that prompts your kidneys to release more sodium. The more sodium, the more urine exits the body. 2

They’re commonly used to lower high blood pressure because lessening sodium helps expel more water from your blood leading to a decrease in pressure flowing against the walls of the arteries and veins. 

When less fluid flows throughout your body, your blood pressure naturally declines.

However, outside of medication, diuretics are anything that causes you to urinate more.

Dehydration is, unfortunately, a common side effect of diuretics.

Natural diuretics, like coffee or caffeinated drinks, have the same effect.

Other natural diuretics or foods that have the same diuretic effect are:3

  • Fruits and vegetables like lemon, celery, garlic, and onions
  • Herbs, like parsley
  • Tea

While caffeine isn’t used to treat high blood pressure, it does encourage your body to expel more sodium and water, which can cause dehydration if done in excess.

Does Coffee Dehydrate You?

Drinking coffee can cause dehydration because the caffeine in it naturally increases urine production—but only if consumed in excess and without adequate replacement of fluids.

Studies show that moderate caffeine consumption is unlikely to dehydrate you, especially since there’s a good amount of water in your cup of coffee.

Caffeine intake that surpasses the recommended four or more cups (i.e. 400 mg) is more likely to cause dehydration.

Caffeine ingestion must be done in moderation to avoid the diuretic effect, as well as any of the following:

  • Unpleasant stomach contractions
  • Insomnia
  • Irritability/mood swings
  • Heart palpitations
  • Tremors

So coffee by itself doesn’t necessarily dehydrate you. The caffeine in it can, but likely won’t if you’re sticking to the recommended amount.

How Much Caffeine Causes Dehydration?

Moderate daily coffee intake is anywhere between one to four cups (400 mg). Any more and you run the risk of dehydration.

Regular coffee drinkers should be cognizant of how much caffeine they’re ingesting. Several cups without any other form of hydration may cause more than just dehydration, even other unpleasant side effects. 

Caffeine can also cause dependence when not regulated and when consumed consistently in the long-term.

Severe caffeine intake (more than ten milligrams per kilogram of body weight) daily can lead to even more serious conditions, like stroke and heart problems.4

This is why moderate coffee intake is important.

Is Instant Coffee Better?

Instant coffee usually contains less caffeine than brewed coffee, which isn’t so appealing to everyone—especially coffee drinkers who take it for its alertness-boosting effects.

So, in a way, instant coffee is less likely to cause dehydration.

This, of course, depends on how many spoonfuls of instant coffee you use. But generally speaking, if you use the same ratios you would with brewed coffee, you would be consuming less caffeine.

However, many coffee lovers tend to write it off because it may not taste as good or as “authentic,” nor does it help them stay as focused given the lower caffeine content.

Depending on your personal coffee habits and schedule, instant coffee may or may not be up your alley. If you’re too busy to do a coffee drip or use a French press every morning, it may be a better option. Otherwise, it’s all up to your taste.

It is worth noting, however, that many instant coffee varieties do have added sugars and additives in them to help preserve and mass produce them. So, if you’re mindful about additives, you may want to read the label more closely.

What Are the Signs of Dehydration?

Dehydration isn’t always so extreme, it can definitely creep up on you. 

Dehydration has three levels: mild, moderate and severe. Mild cases can be treated with oral rehydration while moderate to severe cases need intravenous fluids and/or hospital admission.

Here are a few symptoms of dehydration you should look out for before it gets too severe:5

  • Dark/no urine
  • Rapid heartbeat
  • Ragged breaths
  • Lightheadedness
  • Chills
  • Fever
  • Fainting
  • Fatigue
  • Dry mouth
  • Dry skin

What Other Drinks Cause Dehydration?

Coffee consumption isn’t the only thing that causes dehydration. Other beverages also have a diuretic effect.

Other caffeinated beverages, such as tea and energy drinks, also have a diuretic effect. Because energy drinks are so controversial in terms of their effectiveness and safety, many people tend to avoid them when they can.

Energy drinks contain stimulants and are aggressively marketed as a great way to stay alert and focused.6 Their target market is young, making them a little more sensitive to caffeine since they’re likely not used to it, and are generally smaller than an average adult, making their caffeine threshold smaller.

Other drinks that may cause dehydration when consumed in excess are:

  • Alcohol
  • Soda
  • Very sugary drinks like packaged fruit juices

Stick to decaf over caffeinated coffee if you’re more prone to dehydration. Other caffeine-free coffee alternatives include:

  • Matcha tea
  • Yerba Mate
  • Neuro Gum
  • Chicory coffee
  • Golden milk
  • Kombucha

How to Counter Dehydration

For regular coffee drinkers who want to avoid dehydration, even if it isn’t likely that your regular morning cup will cause dehydration, ensure that you do drink lots of water alongside your pick-me-up.

Avoid caffeinated beverages aside from what you’re already consuming throughout the day. If you take more caffeine than recommended, and even more of it compared to actual water, you run the risk of dehydration.

The recommended water intake per day in an average-sized adult is 8 glasses. This value increases due to additional loss from urination, perspiration and insensible water losses.

Circumventing the diuretic effect can be easy as long as you’re cognizant of how much water you’re drinking and when you know to say no to a fifth cup (if you get that far).

Skip your morning cup or stick to moderate amounts rather than drinking coffee in excess—especially if you’re not too used to it.

Drink enough water throughout the day and make sure you get your recommended eight cups.

Should I Avoid Coffee?

No, you don’t have to totally avoid coffee to keep from dehydration. You can take your regular cup and enjoy its benefits—as long as you don’t do it in excess.

When you drink coffee, you boost your alertness and focus. It’s a great start to the day for many and doesn’t need to be something you give up unwillingly unless your health calls for it.

Regular coffee intake is pretty harmless as long as you stay healthy and don’t develop a sensitivity to caffeine.

Updated on May 30, 2023
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6 sources cited
Updated on May 30, 2023
  1. Caffeine.” Harvard School of Public Health.
  2. Diuretics.” Mayo Clinic.
  3. 6 Natural Diuretics: Foods and Actions to Take.” Cleveland Clinic.
  4. Nutrition and Healthy Eating.” Mayo Clinic.
  5. 10 Signs of Dehydration You Need to Know.” Go Health Urgent Care.
  6. Energy Drink Consumption.” International Journal of Health Sciences.
Dr. Rizza Mira
Dr. Rizza Mira
Medical Reviewer
Dr. Rizza Mira is a medical doctor and a general practitioner who specializes in pediatrics, nutrition, dietetics, and public health.

As a pediatrician, she is dedicated to the general health and well-being of children and expecting parents. She believes that good nutrition, a healthy lifestyle, and prevention of illness are key to ensuring the health of children and their families.

When she’s not in the hospital, Rizza advocates and mobilizes causes like breastfeeding, vaccination drives, and initiatives to prevent illness in the community.
Angela Natividad
Angela Natividad
Content Contributor
Angela Natividad is the content manager and editor for KnowYourDNA. She loves learning about the latest in DNA.
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