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Does Tea Dehydrate You? The Truth About Caffeinated & Herbal Teas

Liz McKinney, MS, CNS, LDN

Published in Nutrition

9 min read

January 19, 2024
a cup of tea
a cup of tea

Tea is one of the world’s oldest beverages and continues to be widely popular today. However, amidst the comforting warmth and diverse flavors that tea offers, a common concern often arises: does tea dehydrate you? 

While tea enthusiasts swear by its numerous health benefits, including hydration, there's a lingering question about whether the caffeine content or other components could potentially counteract these hydrating effects. 

In this article, we’ll delve into all the potential effects of tea consumption to determine whether or not caffeinated drinks like tea really affect your hydration levels.

Does Tea Dehydrate You?

a girl with a cup of hot tea

True teas, which include black, green, white, and oolong, are all made from the Camellia sinensis plant. Some may believe tea is dehydrating due to its mild diuretic effect, leading to increased urine production, despite the overall hydrating properties of the beverage. But is this true?

While a cup of tea is mostly water, it does contain caffeine, which is a naturally occurring compound found in things like coffee, tea, and chocolate. Interestingly, research on habituated caffeine drinkers who drink moderate amounts of caffeine shows no significant dehydrating effect, though in those who drink higher amounts and are not used to drinking caffeinated beverages, a more pronounced dehydration effect may occur. 

Large doses of caffeine can have a diuretic effect, which increases urine production and may contribute to its reputation for being dehydrating. Some research studies, however, indicate that the dose needs to be larger than is typically present in tea.

Generally, the more processed the tea, the more caffeine it contains, with black tea containing the most caffeine, green and oolong teas a moderate amount, and white tea only a nuanced amount. Herbal teas or infusions of herbs in water are generally caffeine-free.

So, drinking excessive amounts of caffeinated tea, especially if you are new to tea, could potentially cause dehydration, but you would need to drink several cups of highly caffeinated tea within a short window for tea to have this effect. 

Different Types of Teas and Your Health

The most noticeable difference in caffeine may come from the tea you start with—whether black, green, or another kind. The precise caffeine content of tea depends on many factors, such as:

  • Which varietal of the camellia sinensis plant the tea comes from
  • Whether the tea is shade-grown (like matcha), which causes the plant to produce more caffeine
  • Water temperature and steeping time
types of tea

According to Dr. Klee Bethel of Sonoran University’s Neil Riordan Center,

“Black teas contain more caffeine and are therefore more stimulating, can have a greater beneficial effect on learning and memory, they can also stimulate the bowel and combat fatigue temporarily. Green tea contains almost as many antioxidants as white tea and therefore can support heart health and may reduce the risk of cancer and certain lifestyle-related diseases.”

Different teas also contain varying levels of other compounds, including:

  • Antioxidants like polyphenols, flavonoids, and catechins
  • L-theanine, an amino acid with a calming effect
  • Phytochemicals, which protect against inflammation 

The polyphenols found in black and green teas have been shown to act as prebiotics in the intestinal microbiome, encouraging the growth of bacteria that produce short-chain fatty acids and thereby positively influencing gut health. Green and white teas are rich in antioxidants called catechins, which protect against the damage caused by free radicals and are known to be anti-inflammatory. 

Green tea, which is especially high in epigallocatechin-3-gallate (EGCG), is highly regarded for its anti-inflammatory properties, with visible benefits for the skin. EGCG is also known to improve the insulin response and a process called mitochondrial biogenesis, both of which can protect against metabolic syndrome and type 2 diabetes.

Naturally non-caffeinated teas have health benefits too. Cinnamon tea, for example, has also been demonstrated to have anti-inflammatory and anti-diabetic properties, while the benefits of herbal teas can be attributed to the actions of the specific herbs they contain.

What to Know About Caffeine and Hydration

Fluid and electrolyte balance may also be the reason too much caffeine can be dehydrating. Caffeine's diuretic effect comes from encouraging the loss of sodium and potassium ions, which leads to an increased production of urine.

caffeine recommendation per day

However, the processes of diuresis and natriuresis, or water and sodium excretion, respectively, have only been observed to lead to a mild diuretic effect when caffeine intake is equivalent to several cups of coffee (500-600 milligrams). Moderate consumption of caffeine does not appear to be dehydrating according to current research.

Tea vs. Coffee for Hydration

While both tea and coffee contribute to daily fluid intake and can be hydrating, you may be wondering whether tea could be a beneficial addition to, or replacement for coffee. Here are some factors to consider when thinking about tea and coffee for hydration:

  • Caffeine: It is generally easier to consume higher doses of caffeine with coffee than it is with tea; however, both coffee and tea, consumed in moderation, can be a part of a healthy diet.
  • Antioxidants: Both coffee and tea are good sources of antioxidants.
  • Energy: Caffeine found in coffee and tea increases alertness and decreases fatigue by increasing the availability of dopamine and by binding to adenosine receptors, preventing adenosine from carrying out its sleep-promoting effects. 
  • Weight loss: Caffeine has been studied for its ability to stimulate thermogenesis, a process by which the body burns calories. Because coffee contains more caffeine than tea, this effect may be more pronounced among coffee-drinkers, although polyphenols may also contribute to weight loss.
  • Hydration: While both coffee and tea contain caffeine, the diuretic effects of this compound won’t dehydrate on their own unless consumed in excessive amounts. That’s because coffee and tea also contain water, which may balance out the effects of the caffeine in moderate doses.

Can You Drink Tea Instead of Water for Hydration?

All teas, and especially caffeine-free herbal teas, can be a part of a balanced lifestyle and contribute to your daily fluid intake. This may be especially true when you’re experiencing fluid imbalance, as many teas contain trace minerals. Some of these, such as sodium, calcium, potassium, and magnesium, are electrolytes.

Electrolytes support hydration by helping to regulate fluid balance through osmosis, a process by which water diffuses across a cell membrane from a place of higher concentration of ions (i.e., minerals) to one of lower concentration. Restoring this balance of minerals forms the basis for the idea that beverages other than plain water can help to hydrate you.

How to Stay Hydrated

Hydration is critical for the body to function properly, affecting everything from skin to kidney function, metabolism, digestive health, and cognitive performance. When you’re well hydrated and consuming enough fluids, you may have more energy and may even consume fewer calories.

According to the Mayo Clinic, men should aim for about 15.5 cups of fluids per day, while women should aim for about 11.5 cups of fluids per day. Signs of dehydration can include things like dizziness, dark urine, fatigue, dry mouth, headache, excessive thirst, muscle cramps, and more. 

daily fluid recommendations

To stay hydrated and meet your fluid needs, our nutritionists recommend:

  • Snacking on foods with high water content, such as cucumber
  • Adding electrolytes to your water
  • Adding herbs or low-glycemic citrus (such as lemons and limes) to your water
  • Spacing out your water intake
  • Setting reminders to drink water

All of these strategies are science-backed, and sipping a cup of tea accomplishes several of them at once—increasing your intake of herbs and electrolytes while nourishing your body with water over time.

Is It Good to Drink Tea Every Day?

Yes, it is generally beneficial to drink tea every day as it offers various health-promoting antioxidants and potential health benefits when consumed in moderation. Keep in mind that the many bioactive compounds found in tea may be tolerated differently depending on your body. 

Some people may be caffeine-sensitive and only able to consume small amounts of caffeinated beverages, while others may not be able to consume any caffeine due to genetic or other health conditions. It’s important to consult a healthcare professional if you’re unsure about your caffeine consumption.

Caffeine is only one bioactive compound, too. When it comes to herbal teas, the phytochemistry of each herb determines how that herb acts in the body. This makes them powerful allies for managing stress, supporting the nervous and immune systems, and more. You may want to discuss any herbs you’re thinking about with your doctor before adding them into your diet.

How Many Cups of Tea Per Day Is Too Much?

From a caffeine standpoint, how much tea is too much depends on your body’s unique biochemical makeup. The Food and Drug Administration recommends not exceeding an upper limit of 400 mg of caffeine per day, but this is a general recommendation.

You may experience caffeine side effects such as:

caffeine side effects
  • Anxiety
  • Headache
  • Disrupted sleep
  • Digestive changes
  • Mood changes at much lower doses. 

The optimal amount of tea for you will be a balance of the powerful benefits of tea for reducing the risk of cancer, diabetes, and cardiovascular and neurological diseases with your individual tolerance of caffeine and the specific compounds the tea contains.

Dr. Bethel continues, “Tea can be made from a large variety of substances and therefore a wide variety of effects can be expected from the consumption. However, tea is 99 percent water and as such is very hydrating. 

Most studies suggest less than ten cups a day is okay, although some research has reported that more than five liters per day can result in skeletal and dental fluorosis. Despite this, most normal consumption is probably safe."

Key Takeaways: Tea and Optimal Hydration

Tea can be a healthy addition to your lifestyle. When considering what to tea to drink (or drink more of), here’s the bottom line:

  • The caffeine content of tea differs depending on the type of tea you choose. Black tea can be good for a higher caffeine boost in the morning, while green, white, and herbal teas may offer more subtle energy in the afternoon.
  • Keep an eye on how much tea you’re consuming. As with most anything, excessive consumption of tea may not be healthy, while moderate amounts can have many health benefits. Paying attention to your body will help you to learn what the right amount is for you.
  • Moderate amounts of tea are not likely to have a negative impact on hydration levels. In addition to water and foods with a high water content, teas or herbal infusions with no or low caffeine levels can aid hydration.
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Jordyn Wallerius, MS, RDN, CD

Reviewed by: Jordyn Wallerius, MS, RDN, CD

Jordyn has a bachelor’s degree in biology, a graduate degree in Human Nutrition and completed a dietetic internship at the Memphis VA. She's a dietitian at Nutrisense, and has experience working as a clinical dietitian at a VA medical center specializing in oncology and at the Mayo Clinic, working with a wide range of patients ranging from neonates in the NICU to adult ICU.