Guayusa benefits and side effects analysis

Guayusa: Benefits and Side Effects

We’ve written this article as you (our readers) have messaged asking us questions about guayusa.

For this reason, we’ve employed doctors and other specialists to tell us more about this ingredient; although we are experts in the supplements industry, this shows how little is actually known about this stimulant so far…

Anyway, in this article you’ll learn:

  • What Is Guayusa?
  • Benefits of Guayusa
  • Side Effects of Guayusa
  • Yerba Mate v Guayusa
  • Green Tea v Guayusa
  • Caffeine v Guayusa
  • Conclusion

What is Guayusa?

Guayusa is a plant native to the Amazon Rainforest which is a specie of the holly genus – one of four holly trees containing caffeine.

For this reason, the leaves of its tree are dried and brewed like a tea for their stimulant effects. In fact, it’s been used for this purpose by Ecuadorians for thousands of years.

Similarly to our own custom of rising from bed to a hot beverage; this plant was traditionally brewed by families each day before the rising of the sun.

Interesting Facts About Guayusa

In the past, the Ecuadorians were known to cluster in sitting arrangements around the fire having drinks of guayusa together as the sun rises, telling stories and myths; with the elders of the village teaching the young ones about ancestors, social norms, and hunting techniques.

While this plant is not basically tea in the traditional sense, it’s brewed as one.

How is it made into tea? Well, the guayusa leaves are dried and steeped in hot water.

One advantage it has over English tea; this plant doesn’t contain the bitter tannins present in normal tea. This means the flavor is not bitter – but tastes silky and clean, with a sweet finish.

guayusa in its natural habitat, being harvested in Ecuador showing the benefits and side effects

Benefits of Guayusa (Why It’s Used)

This plant contains high amounts of xanthines such as caffeine. Other known species of the holly tree that are significantly caffeinated are yerba mate, and yaupon holly (with the other two being english and american).

In addition to caffeine, other beneficial compounds found in guayusa includes most theobromine. What’s theobromine? Answer: another stimulant found in cocoa beans, but comsuming too many stimulants can lead to jitters.


This stimulant is also seen as beneficial due to containing antioxidants.

Why? Well, antioxidants help protect the body against the debilitating consequences of oxidative stress.

What does this mean? Answer: it’s believed that this stimulant can be beneficial for healthy aging and helps decrease the risks of various forms of cancer, heart problems and nervous system disorders.

How much caffeine does Guayusa contain?

You might be surprised to hear that guayusa contains more caffeine content than black tea. In fact, it’s known for containing as much caffeine as black coffee – but this isn’t always a good thing.

Why? Well, while small dosages of this stimulant can raise your energy levels. But as it contains more caffeine than tea, it’s more likely to cause jitters and energy crashes when added to supplements (such as pre-workouts and fat burners).

Side Effects of Guayusa

Although guayusa use may be safe for adults, it’s not a good idea for children because of its high caffeine content – remember that it contains more caffeine than tea, and as much as black coffee.

For this reason, those under 18-years-old should avoid this stimulant and avoid mixing this stimulant with other substances, such as alcohol.

Avoid if you’re sensitive to stimulants

It’s worth noting that even among adults, heavy consumption can cause unpleasant side effects (such as jitters, rapid heartbeat and energy crashes).

As a result; guayusa isn’t a good choice for people who are highly sensitive to its stimulating effects or who take certain medications.

While we always recommend dosages under 200mg caffeine anhydrous per serving (especially in pre-workouts). However, it’s harder to analyze the exact caffeine content in guayusa (meaning it’s easier to consume larger amounts of caffeine when drinking this tea).

Ultimately, consuming too much caffeine can lead to side effects. So we advise that you make sure to check the caffeine content in the guayusa supplement or tea you consume (and consume less than an equal measure of 200mg caffeine anhydrous).

Here’s the side effects from consuming large dosages of guayusa:

  • High Blood Pressure
  • Rapid Heartbeat
  • Anxiety
  • Jitters
  • Energy Crashes
  • Insomnia
  • Headaches
  • Upset Stomach

Bottom Line: Know your tolerance level with stimulants

Some individuals happen to be more sensitive to caffeine than are others – this is a fact.

For this reason, if you’re sensitive to the effects of caffeine – even a cup of guayusa tea can cause the side effects listed above.

We can’t criticize guayusa without comparing it to other stimulants. So that’s exactly what we’re doing in this section below.

a comparison between guayusa v yerba mate and v green tea for a benefits and side effects article

Guayusa v Yerba Mate

We’l start with another highly caffeinated holly tree – Yerba Mate.

These 2 stimulants are very similar product; their leaves can be brewed to form tea, and they only have slight differences.

Below, we’ll give you a full comparison between this stimulant & yerba mate; paying attention to attributes like their origin, chemical composition, effects and taste.

Where are they found?

One common misbelief is that these two herbs are the exactly the same in all aspects.

Although they’re very similar, there are a few differences between them.

First of all, they’re not from the same species; Yerba mate is the plant ilex paraguariensis, while this plant is ilex guayusa. 

But that’s not the only difference. Yerba mate is grown and consumed in the southern parts of South America such as Argentina, Uruguay, Paraguay and Brazil.

On the other hand, guayusa grows in the northern parts of South America – particularly, the Amazon Rainforest and is consumed mostly in Ecuador.

Chemical Composition

Although guayusa and yerba mate are both types of holly trees, their properties aren’t exactly the same.

Here’s the quick answer; Guayusa contains a compound not found in yerba mate. And yerba mate contains a different compound not found in this plant.

But we’l get into more detail below…

Yerba mate contains:

  • Caffeine (85mg in 8oz)
  • Theobromine (mild stimulant found in chocolate)
  • Theophylline.

What’s theophylline? Answer: this isn’t found in guayusa, and is used to treat respiratory diseases such as asthma by relaxing airway muscles, making it easier to breathe.

For this reason, theophylline is believed to reduce stress levels (although no studies have proven this to be a main benefit.

Guayusa contains: 

  • Caffeine (66mg in 8oz)
  • Theobromine
  • L-theanine.

Simply put; L-theanine is what’s missing in yerba mate and this amino acid (mostly found in green tea), relaxes and reduces stress without causing drowsiness.

This amino acid also works great in counteracting the jitters and increased heart rate from caffeine, making L-theanine and caffeine a very efficient combination.

However, while this sounds good; the amount of L-theanine found in guayusa isn’t enough to actually deliver any benefits. This is why supplements have been created with higher levels of L-theanine, alongside caffeine.

In fact, the only natural source that contains a good amount of L-theanine is green tea (which we’ll compare guayusa to in the next section).

Effects (What do Guayusa & Yerba Mate Do?)

After looking at the chemical composition of both guayusa and yerba mate, you should already have an idea what effects they’ll give you.

Simply put, guayusa and yerba mate are both stimulants. Therefore, they’ve shown to boost energy, enhance concentration, and uplift mood,

However, as both are highly caffeinated sources – they come with risks of causing side effects such as jitters and energy crashes.

Although I haven’t tried guayusa, people have said it to be more relaxing than yerba mate in small dosages. Which makes sense because it has a lower caffeine content, and also because it contains the amino acid L-theanine.

But here’s the problem; guayusa is found in supplements (such as pre-workouts and fat burners) in high dosages – which increases your risk of suffering from jitters and energy crashes.

What Do They Taste Like?

Here’s some common questions that people have asked us, here at; does guayusa and yerba mate taste nice? Which one tastes better?

Well, we’ve listened to your questions, and now you’re about to find out…you need to try them both yourself.

Only joking. Simply put, yerba mate tasted bold, earthy, bitter, and smoky (as you can see, I should have become an expert tea critic…)

The degree of each flavor varies depending on the brand. But typically, this is what you can expect.

As for guayusa, it tastes similar to yerba mate – but not as strong or bitter. And it’s also not smoky.

For this reason, many believe that guayusa tasted smoother and that it even has a natural sweetness to it. So the winner of the tasting comparison is guayusa.

However, remember that both contain much more coffee than english tea; this means you’ll have to consume smaller dosages, or risk suffering from side effects such as jitters or energy crashes.

Bottom Line: As guayusa and yerba mate are both contain high amounts of caffeine – there’s an equal chance of these stimulants causing side effects when consumed as tea or in gym supplements.

Guayusa v Green Tea


As we’ve mentioned, guayusa is the leaves of the caffeinated Amazonian holly tree. It’s most commonly dried and steeped in hot water, but supplement companies are

This is similar to green tea; this is a type of tea that is made from Camellia sinensis leaves. However, thats where the similarities end – we’ll explain the differences between these two plants below.


Found in different continents and created differently

One thing better about green tea than guayusa – green tea hasn’t undergone the same drying or withering and oxidation process used to make guayusa tea.

But here’s the main difference; this holly tree and green tea are found in completely different parts of the world,

Simply put, green tea originated originated in China, but its production has spread to many countries in Asia (where it’s highly popular in countries such as Japan).

And as we mentioned, this holly tree is found in South America and is mostly consumed in Ecuador.

There’s more species of green tea 

While there are several different types of green tea, there’s only one variety of guayusa in existence.

All of the varieties of green tea differ substantially because of the variety of C. sinensis used, growing conditions, horticultural methods, production processing, and time of harvest.

Different types of plants

Green tea is unfermented leaves from the camellia sinensis plant. However, guayusa tea comes from unfermented leaves of the its tree. So as guayusa comes from a different plant it has totally different taste and properties from your average green tea.

Green Tea Contains Less Caffeine 

This is the information you need to know; guayusa contains a much higher amount of caffeine than green tea. This makes it more likely to cause jitters and energy crashes when consumed as tea, or in supplements (pre-workouts or fat burners).

Not only that, guayusa contains less L-theanine than green tea – this means guayusa is actually more likely to cause side effects overall.

For this reason, we’d prefer to consume green tea in gym supplements. And as we enjoy drinking tea throughout the day, we’d choose green tea over guayusa tea too.

Bottom Line: Green tea is more beneficial than guayusa, especially in gym supplements (and you can drink green tea more frequently throughout your day without suffering from jitters or energy crashes).

In fact, green tea extract is best known for it’s ability to promote fat loss directly (due to containing catechins, which has proven to boost your metabolism).

Not only that; green tea extract also shown to be one of the best thermogenics you can find in supplements – and contains little to no caffeine (only green tea consumed as tea contains more of caffeine, not when it’s extracted into powder form in supplements).


Caffeine Anhydrous v Guayusa

If you’re looking for the best stimulant in gym supplements (such as pre-workout and fat burners), then this is the section you want to read.

Basically, this stimulant caught our attention as more products were being made with this stimulant inside. But we couldn’t find much information ourselves – so we hired some PHD students and professional nutritionists to give us information about guayusa.

The caffeine content of guayusa isn’t certain 

As you can imagine, not knowing the exact caffeine content of a stimulant isn’t good. This means your risk of suffering from side effects such as jitters and energy crashes are increased.

Ultimately, this is what makes caffeine anhydrous the best stimulant in supplements; as it’s the purest form of caffeine, you know exactly how much you’re consuming in supplements.

Here’s the optimal dosages of caffeine anhydrous in supplements:

Gauyusa is unreliable

We mentioned that guayusa has only started being added into gym supplements. Well, this is because it’s still relatively unknown (which is why you’re reading this article – to find out more information about this stimulant).

For this reason, it’s not actually proven whether guayusa is safe when added into supplements (although consuming moderate amounts as tea is known to be safe).

On the other hand, caffeine anhydrous has been added into supplements for decades. This is why there’s been countless studies conducted on this stimulant – all of them showing that caffeine anhydrous is safe and effective when consumed in sensible dosages (which we bullet pointed above).

Bottom Line: If you’re looking for the safest and most effective stimulant in gym supplements, then caffeine anhydrous is your best option (under 200mg in Pre-Workouts, and under 100mg per capsule in Fat Burner Supplements).


Quick Summary of Benefits

In studies of Guayusa, this tea has been found to contain 50% more anti-oxidants than green tea with the second highest ORAC score of any other food product tested.

This stimulant has been found to balance the body’s pH and blood sugar levels, detoxify the blood, improve the functioning of the kidneys and urinary tract, improves digestion and elimination while strengthening the lungs, removing cholesterol and lowering blood pressure.

  • Contains high amounts of antioxidants
  • Improves general health

Quick Summary of Drawbacks

However studies have also shown this stimulant to contain 90 mg of caffeine per 8oz cup; this makes it the second most caffeinated plant on earth (alongside coffee).

As we’ve mentioned, this also increases its risk of causing side effects such as jitters and energy crashes when consumed in tea or pre-workout and fat burner supplements.

  • Contains HUGE dosages of caffeine
  • Increases your risk of suffering jitters and energy crashes


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13 thoughts on “Guayusa: Benefits and Side Effects”

  1. Well actually, I’ve been drinking guayusa for a while now… I can, at times, be a bit sensitive to caffeine from coffee or tea… I’ve not had that issue at all with guayusa… I feel a steady energy from it, no jitters or crashes and I also seem to feel some real clarity of thought when I drink it as well… so, for my money, it’s guayusa all the way… though I may try blending it with green tea from time to time…

    • Hi Jacinda, thanks for reaching out!

      Guayusa is a great tea to drink, and we have had positive experiences from consuming it via this way too. So we definitely agree with you, that guayusa is a great nutrient to consume as tea, thanks again for your input!

      However, it’s harder to measure the caffeine content in guayusa than in green tea extract, green coffee bean extract or caffeine anhydrous in supplements; ultimately, companies adding uncertain amounts of a stimulant into their products is always cause for concern, and increases the customer’s risk of suffering jitters and energy crashes.

      But again, we can agree that guayusa is great to consume as tea, where you can easily regulate your intake personally 🙂

      Best regards,

  2. Could you provide links to research on the benefits of Guyusa please. Also could yo u find out if you can decaffinate Guyusa, the same way you can decaffinate green tea ie by pouring hot water over the tea and then draining it. then adding more water and allowing it to brew.

    • Hi CP, thanks for reaching out!

      We there haven’t been any studies proving whether your method described is effective at decaffeinating guayusa. However, if you’re worried about the caffeine content of guayusa, we can recommend adding extra l-theanine to your cups of tea; this will enhance the already ample supple of l-theanine in your guayusa tea, which should lower your risk of jitters.

      I hope this helps! With regards, to studies, we use our positions in our professions in the supplements industry to access work that others would have to pay for. For this reason, we can’t freely provide these for everyone to see – one of them being seen in this link:

      You can certainly suscribe to that website so see that study for yourself. Or we found a great free resource providing some (what seems to be) reliable information on guayusa here:

      I hope this helps you, and feel free to ask any further questions!

      Best regards,

    • Hi Trevor, thanks for reaching out!

      You can indeed add L-Theanine to Yerba Mate if you like. You can add it to your cup of coffee in the morning too.

      In answer to your second question, it is indeed believed that Yerba Mate is able to reduce adrenal fatigue. But, to be honest, many people consume coffee (caffeine) and green tea daily without complaining too much!

      Personally, when grabbing a caffeinated hot drink, green tea is our first choice (green tea contains small amounts of L-Theanine naturally, and it’s also generally beneficial to your health). However, in a supplement such as a pre-workout, we prefer the ‘smart combo’ of Caffeine Anhydrous & L-Theanine.

      I hope this answer helps!

      Best regards,

  3. Forgive me, but I have never used workout supplements before, and was wondering what caffeine anhydrous is.
    Also, what loose leaf brand of yerba mate would you recommend?

    • Hi Trevor,

      No need for any apologies, providing information like this is exactly why we set this site up!

      The ‘Anhydrous’ means that Caffeine has been dehydrated into powder form, so it can be added to supplements. So if you see Caffeine in supplements, it’ll be listed as ‘Caffeine Anhydrous’ for the most part.

      In answer to your second question, we don’t buy Yerba Mate ourselves. We’ll have it when we travel to countries where it’s popular (South America etc). If you let us know what your general fitness goals are, we might be able to assist you further.

      Best regards,

  4. I’m a caffeine fiend & biohacker, but I want something better than coffee, and doesn’t hurt my adrenals or change my blood pressure from normal to high.

    • Hi Trevor,

      Unfortunately, any stimulant might tax your adrenals. Now, we’re not doctors or medical professionals, so we can’t give any medical advice here. But we personally try to consume stimulants with our meals so the nutrients and calories take some of the hit instead.

      So if we were really concerned about the effects of stimulants on our adrenals, we would personally give up stimulants completely. We find that staying away from stimulants for a while reduces our tolerance, so we’re happier consuming less coffee again, eventually.

      As we mentioned, we can’t offer medical advice. So let us know if you ever need any help where we have experience in – fitness! Best of luck!

      Team LeanBulking

  5. Hey thanks for this article i spend ages looking for info on guayusa side effects. I too prefer green tea but didn’t know it was l-theanine keeping me more steady – very interesting article.

    • Hey Alessandro (awesome name by the way), thanks for reaching out!

      We’re glad that this article was able to help you out, and it’s exactly why we commissioned this article.

      Let us know if there’s any particular nutrient that you would like more information on.

      Best regards,

  6. Interesting that you state that guayusa has less l-theanine than green tea. Nowadays I usually just use an l-theanine supplement, but guayusa definitely affected me differently than any other caffeinated beverage.

    • Hey Dr. Keat,

      Thanks for your insight into Guayusa, it’s much appreciated!

      Everyone has their preferences, so it’s great that Guayusa works for you. We personally enjoy the taste of Green Tea much more, so it’s certainly something we would rather consume – and indeed, we do too use l-theanine supplements.

      Best regards,


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