Caffeine is a compound naturally found in coffee, tea, cacao, kola nuts, yerba mate, and guarana berries. It acts as a stimulant on your central nervous system, which is how it helps you focus and feel less tired (1).

Of course, it can also cause some unpleasant side effects like anxiety, restlessness, an irregular heartbeat, and difficulty sleeping — which is why it’s generally good not to have too much of it (1).

When my clients want to reduce the amount of caffeine they consume, many of them initially think about switching from drinking coffee to drinking white tea, green tea, black tea, or even Thai iced tea.

While tea is still a source of caffeine, it contains significantly less than coffee.

In this article, I’ll compare the caffeine contents of green tea, white tea, black tea, oolong, matcha, yerba mate, and Thai tea so you can figure out which one may be best suited for your needs.

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The exact amount of caffeine in tea will depend first and foremost on its variety.

Here’s a comparison of the amount of caffeine you can expect per cup (240 mL) of the most common types of teas (2, 3, 4):

  • Black tea: 35 mg
  • Green tea: 32 mg
  • White tea: 34 mg
  • Oolong: 39 mg
  • Matcha: 57–133 mg
  • Yerba mate: 128 mg

Keep in mind that the longer you steep tea, the higher its caffeine content will be. If you wish to lower the amount of caffeine in your cup of tea, consider steeping it for one minute instead of the typical three (5).

What about the caffeine content of Thai iced tea?

Thai iced tea is a beverage made from black tea, condensed milk, and spices. To make it, you typically need to steep the black tea and spices in boiling water for 30 minutes prior to cooling and adding condensed milk.

Because of this longer steeping time, Thai iced tea likely contains slightly more caffeine than a cup of black tea, although the exact difference in caffeine content is difficult to quantify (2).

Other factors that can influence the caffeine content of tea

In addition to the brewing time, the water temperature and whether you’re using a teabag or loose tea leaves will also influence the amount of caffeine in your cup of tea (5, 6).

The higher the water temperature, the easier it is for the caffeine to steep out of the tea leaves (5).

The hardness of your water can also affect the caffeine content of your tea. Tea brewed in very hard water appears to contain up to 1.4 times more caffeine than the same tea brewed in very soft water (6).

If you have hard water running through your home’s pipes, you’ll likely be able to tell by white mineral buildup around your faucets or white spots on the glasses and silverware coming out of your dishwasher.

Finally, tea made from a teabag will typically contain slightly more caffeine than one made from loose tea leaves.

That’s because the leaves found in teabags have generally been ground into finer particles, which allows the caffeine they contain to steep out of them more easily (7).

SUMMARY

The amount of caffeine in your cup of tea will depend on the variety of tea, whether it’s loose or bagged, how long it steeps for, and the temperature and hardness of the water used to make it.

While caffeine is generally considered safe when consumed in moderation, too much of it may cause side effects ranging from mild to severe.

Mild side effects may include trouble sleeping, increased urination, muscle twitches, an upset stomach, irritability, restlessness, anxiety, and an irregular heartbeat.

Severe symptoms can include disorientation, hallucinations, psychosis, or seizures. However, these severe side effects are generally caused by a much larger caffeine consumption than is typical (1).

How much caffeine is too much?

According to the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA), daily intakes of up to 400 mg of caffeine per day are safe (8, 9).

To put this into perspective, this would amount to about 8 cups (1.9 liters) of black, green, white, or oolong tea, or about 3 cups (720 mL) of matcha or yerba mate.

However, too much caffeine during pregnancy may be linked to lower birth weights and an increased risk of miscarriage (1).

The evidence behind this link is weak, but to be on the safe side, pregnant people are often advised to limit the amount of caffeine they have to 200 mg per day or less. More research is needed to understand the effects of caffeine on pregnancy.

SUMMARY

Too much caffeine can cause a variety of mild to severe side effects. To minimize your risk, aim to limit your tea consumption to 3-8 cups per day, depending on the variety.

There is currently no evidence that caffeine should be avoided completely.

That said, people with the following medical conditions are generally advised to limit their caffeine consumption (1):

  • Severe anxiety disorders
  • Heart disease or an irregular heartbeat
  • Gastric ulcer
  • Reflux
  • Liver or renal issues
  • Seizures

Caffeine can also interact with the function of certain pharmaceutical drugs, which can cause a toxic reaction, enhance, or reduce their function.

If you’re currently taking any medications, make sure to double check with your healthcare provider if caffeine can interact with them.

It’s also worth noting that, based on genetics, some people are more sensitive to caffeine than others. If you’re one of them, you may experience side effects even if you only ingest small amounts of caffeine (1).

If you’re sensitive to caffeine, favor small amounts of black, green, white, or oolong tea over matcha or yerba mate — or stick to herbal teas instead.

SUMMARY

People taking certain medications, who are caffeine-sensitive, or who have certain medical conditions, such as heart disease or severe anxiety, should consider limiting or avoiding caffeine.

The amount of caffeine in tea will depend on the variety and methods used to make it. Generally speaking, green, white, black, and oolong teas will contain less caffeine than Thai iced tea, matcha, or yerba mate.

To avoid consuming excess caffeine, try limiting your daily intake to 3-8 cups of tea, depending on the variety.

If you’re particularly sensitive to caffeine or have severe anxiety, heart disease, reflux, gastric ulcers, seizures, or liver or renal issues, consider limiting your intake or switching to herbal tea instead.

And if you’re taking medications, be sure to ask a healthcare professional whether it’s safe for you to consume caffeine and how much is OK per day.

Just one thing

Try this today: Switching from coffee to tea is a great way to cut down on your caffeine consumption. To further reduce the amount of caffeine in your tea, opt for loose tea leaves instead of teabags and steep it for one minute instead of the typical three.