While some teas contain caffeine, which can be dehydrating, it’s usually not enough to have a significant impact. In moderation, even caffeinated teas can still be hydrating.

Tea is one of the most popular beverages in the world.

It can be enjoyed warm or cold and can contribute to your daily fluid needs.

However, tea also contains caffeine — a compound that can be dehydrating. This may leave you wondering whether drinking tea can truly help you stay hydrated.

This article uncovers the hydrating and dehydrating effects of tea.

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May Affect Your Hydration

Tea may affect your hydration — especially if you drink a lot of it.

That’s largely because some teas contain caffeine, a compound also found in coffee, chocolate, energy drinks, and soft drinks. Caffeine is a natural stimulant and one of the most common food and beverage ingredients in the world (1).

Once ingested, caffeine passes from your gut into your bloodstream and makes its way to your liver. There, it’s broken down into various compounds that can affect how your organs function.

For instance, caffeine has a stimulating effect on your brain, boosting alertness and reducing feelings of tiredness. On the other hand, it can have a diuretic effect on your kidneys.

A diuretic is a substance that can cause your body to produce more urine. Caffeine does this by increasing the blood flow to your kidneys, encouraging them to flush out more water (2).

This diuretic effect can cause you to urinate more frequently, which may affect your hydration more than non-caffeinated beverages.

Summary

Some teas contain caffeine, a compound with diuretic properties. This can cause you to urinate more frequently when drinking tea, potentially affecting your hydration.

Different Teas May Have Different Effects

Different teas contain varying amounts of caffeine and may thus affect your hydration differently.

Caffeinated Teas

Caffeinated teas include black, green, white, and oolong varieties.

These teas are made from the leaves of the Camellia sinensis plantand generally provide 16–19 mg of caffeine per gram of tea (3).

As the average cup of tea contains 2 grams of tea leaves, one cup (240 ml) of tea will have around 33–38 mg of caffeine — with black and oolong containing the most.

That said, the caffeine content of teas can vary from one batch to another, with some providing as much as 120 mg of caffeine per cup (240 ml). It’s also worth noting that the longer you brew your tea, the more caffeine it may contain (1, 4).

To put this into perspective, one cup (240 ml) of coffee usually provides 102–200 mg of caffeine, whereas the same quantity of energy drink can offer up to 160 mg (1).

Though tea is lower in caffeine than many other caffeinated beverages, drinking large quantities could affect your hydration status.

Herbal Teas

Herbal teas like chamomile, peppermint, or rosehip are made from the leaves, stems, flowers, seeds, roots, and fruits of various plants.

Unlike other types of tea, they don’t contain leaves from the Camellia sinensis plant. Therefore, they’re technically considered herbal infusions rather than types of tea (5).

Herbal teas are generally caffeine-free and unlikely to have any dehydrating effects on your body.

Hybrid Varieties

Though most herbal teas don’t have any caffeine, a few mixes include caffeine-containing ingredients.

One example is Yerba mate — a traditional South American drink that is gaining popularity worldwide.

It’s made from the dried leaves and twigs of the Ilex paraguariensis plant and contains 85 mg of caffeine per cup on average — slightly more than a cup of tea but less than a cup of coffee (6).

Although less commonly consumed, herbal infusions including guayusa, yaupon, guarana, or coffee leaves are also likely to contain caffeine.

Therefore, just as is the case with other caffeine-containing teas, drinking large quantities of these teas could reduce your body’s water balance.

Summary

Black, green, white, and oolong teas contain caffeine, which may affect your hydration status. Besides a few exceptions, most herbal teas don’t contain caffeine and are generally considered hydrating.

Unlikely to Dehydrate You

Despite the diuretic effect of caffeine, both herbal and caffeine-containing teas are unlikely to dehydrate you.

To have a significant diuretic effect, caffeine needs to be consumed in amounts greater than 500 mg — or the equivalent of 6–13 cups (1,440–3,120 ml) of tea (7, 8).

Researchers report that when consumed in moderate amounts, caffeinated drinks — including tea — are as hydrating as water.

In one study, 50 heavy coffee drinkers consumed either 26.5 ounces (800 ml) of coffee or the same quantity of water each day for 3 consecutive days. Comparatively, that’s the approximate caffeine equivalent of 36.5–80 ounces (1,100–2,400 ml) of tea.

Scientists observed no difference in markers of hydration between the days where coffee and water was drunk (9).

In another small study, 21 healthy men drank either 4 or 6 cups (960 or 1,440 ml) of black tea or identical amounts of boiled water over 12 hours.

Again, the researchers noticed no difference in urine production or hydration levels between the two drinks. They concluded that black tea seems to be as hydrating as water when consumed in amounts smaller or equal to 6 cups (1,440 ml) per day (10).

In addition, a recent review of 16 studies notes that a single dose of 300 mg of caffeine — or the equivalent of drinking 3.5–8 cups (840–1,920 ml) of tea at once — increases urine production by just 109 ml compared to the same quantity of non-caffeinated drinks (11).

Therefore, even in cases where tea does increase urine production, it doesn’t cause you to lose more fluids than you originally drank.

Interestingly, researchers note that caffeine may have an even less significant diuretic effect in men and in habitual caffeine consumers (11).

Summary

Tea — especially consumed in moderate quantities — is unlikely to have any dehydrating effects. However, consuming large amounts of tea — for instance, more than 8 cups (1,920 ml) at once — may have an insignificant dehydrating effect.

The Bottom Line

Many types of tea contain caffeine, a diuretic compound that can cause you to urinate more frequently.

However, the caffeine content of most teas is very low. Drinking normal amounts — less than 3.5–8 cups (840–1,920 ml) of tea at once — is unlikely to have any dehydrating effects.

All-in-all, tea can provide an interesting alternative to plain water in helping you reach your daily fluid requirements.