Does Oolong Tea Have Caffeine? (Benefits & Side Effects)

Although I'm a huge coffee fan, I can't drink a lot of it as I'm caffeine sensitive. I need to be very careful with how much coffee I consume, or else my heart will explode.

Kidding aside, I’ve replaced my afternoon coffee with oolong tea. While I was sipping my second cup in the afternoon, I started wondering, does oolong tea have caffeine?

That’s why I went ahead and did this guide to help out caffeine-sensitive people like me!

In this article, I’ll discuss the caffeine content of oolong tea, its numerous health benefits, and how it compares with other tea types.

Let’s dig in!

The answer is yes, oolong tea contains caffeine. Like many types of tea, oolong tea leaves are semi-oxidized to a level between green and black teas.

This partial oxidation is responsible for the caffeine content of oolong teas. So how much caffeine does it have?

Oolong teas are heavily oxidized compared to green tea and lightly oxidized compared to black teas. This makes the caffeine levels of oolong in between green tea and black tea.

Generally speaking, a cup of oolong tea (8 oz) contains about 40 to 80 mg of caffeine, depending on the type, variety, and brand.[1]

However, not all oolong tea leaves are the same. While there are only two major types of oolong tea (green oolong and dark oolong), they come in many varieties.

These varieties are categorized on where the tea plant is grown - including the altitude, temperature, and location--and the oxidation process. I know - it's a lot of information!

On top of that, there are also different brands that produce this tea.

These factors can affect how much caffeine a cup of oolong contains, but I wanted to get the clearest picture I could because it’s important for me to know how much caffeine I’m consuming.

So, here are the most famous oolongs and their caffeine content below.

Note: Caffeine levels are compared by using the same amount of tea leaves steeped in the same amount of hot water and steeping temperature.

1. Phoenix Tea

Also known as Dan Cong tea, this Chinese oolong tea comes from the Guangdong Province in southern China.

It is the most popular type of oolong and is known for its natural flavors and aroma, which is rich, full-bodied, and fragrant. It contains about 37 to 45 mg of caffeine per 8 oz cup.[2]

Phoenix Single Clump Oolong Tea

2. Tieguanyin Tea

Another popular Chinese oolong tea is Tieguanyin, or the Iron Goddess of Mercy. Grown in the province of Fujian, China, this oolong tea has less caffeine compared to other varieties of oolong.

It has only 12 to 14 mg of caffeine per serving of 8 oz cup.[3]

This tea is perfect for those looking to lessen their caffeine consumption, like me.

3. High Mountain Oolong Tea

As its name implies, this type of oolong tea is grown in the high mountains of central Taiwan. Also called Gaoshan, this oolong tea is lightly oxidized, similar to green tea.

As a result, it has similar caffeine content as green tea. A serving of an 8 oz cup contains 30 to 50 mg of caffeine.

4. Other Varieties And Popular Brands

Apart from these different types of oolong, here are some of the most popular brands of oolong and their caffeine content:

Peach oolong tea: 82 milligrams of caffeine per 16 oz bottle[4]

Milk oolong tea: 37 to 50 milligrams of caffeine per 8 oz cup

Twining oolong tea: 12 to 15 milligrams of caffeine per tea bag[5]

FGO oolong tea: 40 to 80 milligrams of caffeine per tea bag

porcelain mugs ready for oolong tea

What Exactly Is Oolong Tea? (Origin And Ingredients)

Now that I’ve answered the question “Does oolong tea have caffeine?”, it’s now time to discuss what exactly this tea is and where it originated.

There are several stories about how oolong tea was first discovered. The first story is called the tribute tea theory.

According to this theory, the name oolong is a tribute to its predecessor, the Dragon-Phoenix tea cakes, a tea famous during the Song Dynasty era.

The old term was then replaced by oolong, coming from the word “wūlóng,” meaning dark dragon. This term refers to the physical attributes of the tea--dark, long, and curly.

The next one is called the Wuyi theory, which suggests that the tea originated from the Wuyi mountains of Fujian, China.

The name oolong comes from the part of the mountains where it was first discovered.

The last story is called the Anxi theory.

The theory tells us that oolong tea was discovered by a man named Wu Liang, Sulong, or Wulong, who accidentally oxidized his tea after getting distracted by a deer.

Whichever theory is right, the discovery of oolong tea is an excellent contribution to the tea culture. I just know that I like it!

Oolong Chinese Tea Isolated

So, where does oolong tea come from?

Like all types of tea, oolong tea is made from a Camellia Sinensis plant, produced through a process of withering the plant under the sun and oxidation before twisting and curling the leaves.

The oxidation of oolong tea falls between green and black tea, which is why its caffeine levels are in between these two teas. Black tea generally has more caffeine, while green tea contains less caffeine.

There are also some caffeine-free versions of oolong tea, which is a good choice for those who can't consume caffeine at all.

When it comes to the flavor profile, the taste can change depending on the oxidation process.

Lightly oxidized oolong can taste bright, floral, fresh, and sweet, while the highly oxidized versions tend to taste grassy, darker, and mellow.

Other variants can taste woody, fruity, or nutty, depending on how it is prepared.

Benefits Of Regularly Drinking Oolong Tea

If you consume oolong tea daily, you’ll be happy to hear that it offers health benefits that you wouldn’t expect from a simple cup of tea.

Oolong tea contains a lot of antioxidants, which are responsible for the numerous benefits it offers. If you haven’t been drinking oolong tea a lot like I have been, these benefits may push you to start consuming more.

Here are the things you’ll get with continuous oolong tea consumption:

Reduces Heart Disease Risk

Oolong tea is known to help aid in reducing high blood pressure and cholesterol levels, which can help lower the risk of heart disease and hypertension.[6]

In fact, regular tea consumption, not just oolong, can help improve heart health.

Helps With Weight Loss

Drinking tea regularly is believed to aid weight loss, and indeed, many studies have proved the efficacy of oolong tea leaves in increasing metabolism.[7]

That's why oolong tea is hugely popular with people trying to lose weight.

Manage Diabetes

Polyphenols, one of the antioxidants present in oolong, are known to help lower blood sugar.[8] As a result, oolong tea helps lower risk of developing type 2 diabetes.

On top of that, oolong tea extract can reduce insulin resistance, a condition where the body doesn’t properly utilize the sugars in the blood.

Lowers The Risk Of Cancer

Drinking green tea, black tea, and oolong tea can help with cancer prevention, especially with certain types like ovarian cancer.[9]

Other research also claims that it can reduce cancer cell division, thanks to the tea antioxidants found in oolong.

Promote Relaxation And Cognitive Performance

Oolong contains L-theanine, an amino acid that is linked to the promotion of relaxation and cognitive function.[10]

On top of that, the caffeine found in a cup of tea can help maintain alertness and increase energy levels.

Important reminder: Just because oolong tea provides many benefits doesn't mean you should overdo it on consumption. Too much tea drinking may upset iron homeostasis in your body, which can make iron absorption more difficult.[11] It’s better to consume it in moderation.
Oolong Tea Cups Comparison

Caffeine In Oolong Tea Vs Other Drinks

Let’s now compare the caffeine content of oolong tea with other tea types. Here are them:

Oolong Tea Caffeine Vs Green Tea

Green tea doesn't undergo too much oxidation, unlike oolong tea.

That's why the oolong tea caffeine content is generally higher than green tea. In general, oolong contains 40 to 80 milligrams of caffeine, while green tea has 30 to 40 mg.

Oolong Tea Caffeine Vs Black Tea

Black teas are highly oxidized, that’s why they have higher caffeine content in comparison with oolong and other types of tea like white tea and herbal teas.

Generally, black tea has about 50 to 100 milligrams of caffeine, depending on the brand and variety.

Oolong Tea Caffeine Vs Coffee

Coffee has higher concentrations of caffeine, that's why oolong has lower caffeine content.

A cup of coffee can have 40 to 400 mg of caffeine, depending on many factors, like how it's brewed and the beans used.

That's why brewed tea is considered a healthy drink compared to coffee.

Oolong Tea In Pot Being Poured

Common Questions About Oolong Tea

What does Oolong taste like?

The taste of oolong tea depends on how the tea leaves are oxidized. Highly oxidized oolong tea has a stronger bolder flavor, while a lightly oxidized one has a flowery and sweet taste.

Will oolong tea keep me awake?

Yes, highly concentrated oolong tea can keep you awake. However, it has significantly less caffeine than coffee, so brewing tea may not yield the same results as brewing coffee for energy.

Can oolong tea make you sleepy?

Some oolong tea can make you sleep. However, the actual effects of this tea depend on each person.

Is it safe to drink oolong tea every day?

Yes, it is safe to drink oolong tea every day, as long as you don’t consume a lot each day.


Oolong does contain caffeine, but its caffeine content can vary depending on the type, variety, and brand.

So, whether you enjoy drinking regular oolong tea or artisan tea, expect a little caffeine kick from it. On top of that, oolong offers numerous health benefits.

Steep some oolong tea now and see the difference it can make in your day!



Kim Fernandez


Kim Fernandez
Kim offers a unique perspective on coffee culture and trends. Kim's writing is personal and experiential, providing readers with firsthand advice on the latest in coffee. Beyond her writing, Kim is an avid explorer of new coffee trends and spots, always seeking to share the most genuine advice and latest trends. True to her love for coffee, you'll often find her in a café, immersed in a book with a freshly brewed cup of joe.

My favorite drink? I'd go with... A freshly brewed cup of joe

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