In this article I will look in depth at Guayusa health benefits and side effects, looking at some interesting studies. Feel free to go straight to the section that interests you using the contents menu! If you’re less interested in the science, and more interested in the origins of Ilex Guayusa, click here.

Briefly, for those who don’t know what Guayusa is: Guayusa is a species of holly tree native to the Amazon rainforest in South America. It is grown on family farms by the native people mostly in Ecuador who brew guayusa mostly to improve mood and provide a energy boost.

Health Benefits and Side Effects of Guayusa Tea


  • Amount of caffeine is about equal to that in a cup of coffee: Improved wakefulness, focus, and greater mental and physical performance (click here to read about some benefits of Guayusa for athletes)
  • Raises histamine; Improving cognitive performance and mood.
  • Better for regular drinking in regards to health, especially compared to coffee (more explanation later – also see our article comparing Guayusa vs Coffee)
  • More heart healthy chlorogenic acids compared to roasted coffee and tea.
  • Particular to Guayusa tea: a calm, warm sense of energy – rather than the jittery, anxious energy of coffee. May help to avoid high blood pressure and reduce risk of heart disease.
  • Keeping good oral health (click here to learn why)

Guayusa is great as a healthy alternative to coffee. It provides an equal amount of caffeine, but without the jitters or anxiety than can come with coffee. Due to a much lower epinephrine response from guayusa consumption, it can be considered safer to drink than coffee for those with high blood pressure. In addition, guayusa has a high antioxidant capacity provided from a range of nutrients, including heart healthy polyphenols.

Side effects:

A high caffeine intake can be dangerous, so as with all caffeinated beverages; drink in moderation.
Tolerance levels are different from person to person, but if you consume too much (300mg-400mg, that would be 4-6 cups of Guayusa brewed at full strength), you are likely to experience at least some of these symptoms:
  • Headache
  • Anxiety and insomnia
  • Irritability
  • Frequent urination or inability to control urination
  • Fast heartbeat
  • Muscle tremors
  • Nausea
  • Fatigue – after the caffeine levels have reduced in your bloodstream you may feel more tired than normal. As if your body has to ‘catch up’. Best to not drink too much caffeine for this reason.
It also raises histamine a little, a small amount is a good thing, but if your histamine levels get too high you may experience these effect
  • Itchy skin, eyes, ears, nose
  • Difficulty Sleeping
  • Hives, rashes, athletes foot
  • Tissue swelling, especially facial and throat
  • Hypo-tension (drop in blood pressure, dizzy when you stand up quickly)
  • Rapid heartbeat, heart palpitations
  • Anxiety or panic attack
  • Chest pain
  • Nasal congestion
  • Seasonal allergies
  • Conjunctivitis (red itchy and watery eyes)
  • Headaches and migraines
  • Fatigue, confusion, irritability
  • Digestive upset
  • Heartburn and re-flux
  • Blackouts and loss of consciousness
  • Generally speaking, with 2 or more cups of Guayusa, you are more likely to experience:
    • More pooping (though you could consider it a cleanse)
    • More peeing
    • More thirsty than you would have been if you had just drunk water
  • And if you have it within 5 hours of going to sleep:
    • Difficulty Sleeping
    • Lighter less fulfilling sleep (maybe some lucid dreams)

The Quick Takeaway

Don’t let all that list scare you, as they say, too much of anything is bad thing.

If you regularly consume caffeine, or your lifestyle/job requires you to perform at you best, Guayusa is a good alternative for daily usage compared to coffee. As always, the caffeine will enhance mental and physical performance, although from my analysis, I conclude that consuming Guayusa regularly is safer and better for your cardiovascular health than consuming coffee regularly.

However if you find you have difficulty sleeping or experiencing any other negative effects of high histamine levels, stop drinking Guayusa immediately. It is also important to have ways of winding down in the evening, since nothing is more performance enhancing that a good nights sleep.*1

Guayusa health benefits and side effects

For more comparisons between Coffee vs Guayusa see this article.

Common Myths about Guayusa

  • It has a low tannin content. It has a tannin content equal to and if not more than ordinary tea.*2 That’s not necessarily a bad thing, it’s even a good thing, since all tannins are polyphenols, and polyphenols have many health benefits. The marketing claim that the “tannins in coffee stain your teeth but Guayusa does not” needs investigation. Tannins are also known for blocking iron absorption, but further research has shown that only non-heme iron is blocked.*3
    • Although one thing about the tannins is definitely true from experience. Guayusa is definitely naturally sweeter and less bitter than comparable high tannin drinks like tea, coffee or yerba mate (ilex paraguariensis). This could be to do with the type of tannins. Neither do you experience the common ‘dry mouth’ feeling as is normally felt in other high tannin drinks. There must be a particular form of tannin that Guayusa is low in that is causing this difference. UPDATE: It does seem Guayusa is lower in the types of tannins that taste bitter, article about this coming soon.
  • The L-theanine content is significant and works synergistically with the caffeine. False. The l-theanine content is negligible.
  • The theobromine and theophylline content is significant. False. Again, both are of negligible amounts.

The Juicy Details

In the name of good research I will try and reference everything appropriately. When the reliability of a source of information is more dubious, this will be pointed out. We hope you learn something here that you could not have found anywhere else, and enjoy!

Key Components of Guayusa


Starting with the basics. Guayusa has a relatively high caffeine content. One serving of 5g*4 brewed for 10 minutes will contain about 82mg*5 of caffeine. A cup of coffee contains on average 94mg of caffeine*6. For comparison, tea has on average between 14 to 61mg of caffeine per serving*7

Important note: When comparing tea directly to Guayusa, it is important to note, that per dry weight the caffeine levels are similar*8, or Guayusa may even have less caffeine per gram than tea. However, since Guayusa is brewed stronger (and tea would be difficult to brew stronger since it will become too bitter from its tannin content), Guayusa ends up being more highly caffeinated. For the same reason, we will find that a Guayusa brew is also often more nutrient dense than most teas.

Theophylline and Theobromine

Another two psychostimulants present in Guayusa are called, theophylline and theobromine. Just like caffeine, these are both part of a group of compounds called ‘methyxanthenes’. They are found mostly in tea and cocoa.

Theobromine has been reported in Guayusa to be 0.08-0.25mg/g*9(0.008-0.025%), this is compared to 1.5-3% in cocoa beans, 0.02mg/g (0.02%) in green coffee beans, 0.15-0.2% in tea and 0.3% in dried mate. So it is rather negligible; more similar to coffee, and much lower than yerba mate and cocoa beans respectively. Theophylline content is even more negligible at levels of 0.002-0.005mg/g.


Guayusa also contains L-theanine (an amino acid that promotes a sense of calm). It has about 1.3mg/g of dried leaf compared to tea which contains about 20-50mg/g of dried leaf. Once again the levels of Guayusa are too low to have any meaningful impact on the drinker.*10

Companies trying to market the benefits of Guayusa often talk about the high theobromine and theophylline levels, and the L-theanine levels, although from this research, I would conclude that it contains comparatively small amounts of all. Small enough to say that they are irrelevent in normal consumption.

Chlorogenic Acids

What may be more relevent is the chlorogenic acid content in Guayusa (it is a known anti inflammatory, . It has similar levels to green coffee beans in fact.

26.5mg/g of chlorogenic acid per dry weight in guayusa compared and total phenolics of 106.62 for blanched guayusa compared to 54.87mg/g for unblanched guayusa. Very interesting find, from now on we will always recommend blanching guayusa, even if it may wash a small amount of caffeine out. Green coffee beans for comparison contain 35-75mg/g*11, so not too dissimilar. Of course, note that roasting the coffee beans will destroy a lot of it. Green tea for comparison is measured as 0.366mg/g for dry leaves.*12 Green yerba mate is 23.8mg/g and toasted yerba mate is measured as 3.16mg/g. Almost all yerba mate available to buy is smoked, which we guess is similar to toasting. (for more comparisons of guayusa vs yerba mate click here)


Guayusa contains 19 out of a total of 20 existing essential and non-essential amino-acids (glycine, asparagine, serine, aspartic acid, glutamine, theonine, alanine, glutamic acid, proline, lysine, valine, histidine, methionine, arginine, tyrosine, isoleucine, leucine, phenylalanine, and tryptophan).

Amino acids are the building blocks of protein and are needed for building proteins and synthesis of hormones and transmitters. The best sources are foods that are high in proteins, the small amount you get from guayusa will help, but you will still need to eat other foods to reach your intake requirements.

The Most Interesting StudyWhat makes Guayusa special.

So far nothing is too shocking… and then there’s the study funded by Applied Food Sciences (AFS) and conducted by Miami Research Associates*13. Normally it is wise to be dubious when a study is funded by a company that has special commercial interest in the product. In this case, I have no reason to believe there was any foul play, although I would still like to see this replicated in another similar study.

The study itself is a double-blind crossover clinical trial comparing human consumption of 200mg of caffeine from AMATEA™ Guayusa extract to 200mg of caffeine from a green coffee extract. The results were nothing short of remarkable*14. Adrenalin levels in the subjects were 6-7x less for those that consumed the Guayusa extract. Meanwhile, norepinephrine, acetylcholine, serotonin and histamine levels were significantly higher. Evidently the bodies chemical response to guayusa compared to coffee is quite different, and this is what I will further investigate with you, to figure out exactly what is happening, how it effects to body, and hopefully figure out why it’s happening.

What happens to the guayusa drinker compared to the coffee drinker?

1. While Adrenalin (epinephrine) decreases 6-7x, Noradrenalin (norepinephrine) output is about doubled. Ephinephrine and norepinephrine have similar effects on the body on the whole though there are some subtle and important differences. Epinephrine has more an effect on the heart, while norepinephrine works on the blood vessels – mainly to increase and maintain blood pressure. “Norepinephrine is continuously released into circulation at low levels while epinephrine is only released during times of stress.”*15

2. Acetylcholine levels are doubled on average. Acetylcholine is a neurotransmitter commonly used as a supplement for those who want to improve memory and cognition.

3. Seratonin (the “happy hormone”) levels were 2-3x as high. Apart from regulating the mood, seratonin also aids cognitive function.

4. Histamine levels are almost tripled in a similar pattern to seratonin. You might remember histamines as that thing that you want to get rid of with ‘antihistamines’ when you’re suffering from hay-fever. But they’re not always the enemy, they are mainly known as an immune response to remove allergens from your body by making you sneeze, tear up or itch. Sometimes harmless things such as pollen or dust can trigger the histamine by accident, that’s when you may take an anti-histamine to alleviate the symptoms.

But histamine is much more than immune system support. It is a neurotransmitter, and is actually directly responsible for the increase in epinephrine, acetylcholine and seratonin. It regulates aggression and the sleep-wake cycle.

Raised histamine levels from guayusa is most likely from blocked Dao receptors in the same way mate, tea and energy drinks do.*16

On one hand high performers tend to have high histamine levels, on the other hand, if the levels are too high there are numerous unwanted side effects*17. Decreased brain histamine causes neurobehavioural symptoms such as anxiety-like behaviors and impaired learning/memory. In contrast, increased brain histamine produces appetite suppression, anxiolytic actions and improves cognitive function.*18

So you want high histamine levels, but not too high, and only when you need to perform – definitely not when you need to wind down, sleep or relax.

See the graph below to see the differences in effects on the body.

Energy Level comparison; tea, coffee and guayusa
Visual Comparison of guayusa, tea and coffee

What I am trying to show in this graph, is the differing effects of coffee, tea and guayusa; it is not based on exact science – it is merely a visual representation of the subjective effects of the different drinks – I hope it helps to explain the interesting effects of Guayusa. By ‘energy level’ I am referring to the subjective feeling of energy that comes with consuming caffeine. Coffee, as you can see, gives the biggest and fastest caffeine boost which results in a high state of alertness. However, once the caffeine wears off there is the inevitable crash that can come after prolonged raised adrenal levels. Tea, being much lower in caffeine will give a gentle boost, and therefore a much gentler come down. Guayusa has the ability to give a sustained feeling of energy. This is because it doesn’t tax the adrenal system, provides a slow absorption of caffeine while also working through the histamine pathways. The come down is so smooth it is unlikely you will notice by the time the caffeine wears off.

Recommended use case for Guayusa compared to Coffee

So, to reiterate the difference between coffee and Guayusa. Coffee elicits a much greater flight or flight (adrenal) response, while Guayusa stimulates the expression of histamine, which is more about up-regulating the mind and body when it is performing at a high level. The way I would interpret this to apply it for our own use: Guayusa is good for maintaining high levels of performance throughout the day, while coffee is good for acute periods of performance, for example sprints. This is all the more true because the caffeine from coffee peaks and falls a lot faster than that from Guayusa, something I’ll talk about under the next heading.

It is also important to consider the effect of high adrenal levels from coffee. “Persistent epinephrine surges can damage blood vessels and arteries, increasing blood pressure and raising risk of heart attacks and strokes”*19Most people are familiar with the fact that chronic stress is bad for you body long term. So it seems wise to use coffee sparingly compared to Guayusa for the sake of long term health.

The rates of release of caffeine

The caffeine consumed from guayusa absorbs a lot slower into the bloodstream compared to that of roasted coffee. The main reason for this is that the high level of polyphenols in Guayusa slow down the digestion of the caffeine, while roasted coffee has very little polyphenols because they are damaged in the roasting process (unlike coffee made from green coffee beans which would have a very similar rate of caffeine release).

Because of this the caffeine from Guayusa may taper over a period of 4-5 hours in contrast to coffee lasting 2-3 hours.

What have we learnt?

Unlike what I previously thought, the reason Guayusa drinkers don’t get the coffee jitters is nothing to do with the L-theanine, but everything to do with the histamine vs adrenaline response.

The histamine increased triggered by Guayusa consumption up-regulates expression of serotonin, acetyl-choline and nor-epinephrine, improving your mood and improving your cognitive performance.

Coffee on the other hand triggers much higher levels of adrenaline in the body, possibly with long term consequences.

What we still don’t know?

We don’t know why the adrenal response of Ilex Guayusa is a lot lower than coffee. I have a suspicion it’s something to do with the raised histamine levels, though I cannot find any study proving a direct correlation.

Disclaimer: Please do not take anything from my articles as medical advice. I am not a qualified health professional, I’m only trying to unearth the facts best I can. If you want to make changes to your diet it is always best to speak to your doctor.


1* Ted talk – Sleep is your superpower -Matt Walker.

2* Other websites have made claims that the tannin content in Guayusa is low, but have provided no evidence. I think RUNA was the first to make the claim, and being taken as an authority on Guayusa many have taken it as fact. We ourselves have been guilty of it talking about the low tannin content of Guayusa. It could be about the mix-up around tannins and pseudo-tannins. For most intents and purposes pseudo tannins and tannins are all simply classified as tannins. They are similar in almost all ways except molecular weight. Pseudo tannins are smaller molecules than tannins. The only difference I can find is that tannins (not pseudo tannins) can be used for tanning leathers (staining a darker colour). Whether this also extends to teeth, where tannins stain teeth but pseudo tannins do not, I don’t know. Although it sounds plausible. If anyone (who has a knack for science) can figure this out for us this read might help. For investigation: Do pseudo tannins stain teeth? How much tannins vs pseudo tannins does guayusa have compared to coffee, black tea and green tea? Therefore, can we claim guayusa stains teeth less than coffee, or/and tea?

This study shows that the gallic acid content in guayusa is around 116mg/g. Why does that matter? Because there are actually 3 major groups of tannins. Two of those are from gallic acid and chlorogenic acid, the other is from catechins (which included EGCGs). Guayusa is high in catechins, chlorogenic acids and gallic acid, and therefore in not low in tannins.

3* Tannins reduce iron absorption although only non-heme iron.

4* The serving size is calculated from the traditional serving of 5 leaves per cup as drunk by the Kichwa tribe of Ecuador see this link for reference. We then aquired some leaves and found that on average they weigh 1g, and so came up with the number – 5g per cup.

5* On average, although the caffeine content can vary significantly from season to season and from farm to farm. Because Guayusa is grown in the rainforest, not in a controlled envirornment, these variations are inevitable. The caffeine in a cup hot brewed from 5g of Guayusa can range from anything between 60mg and 100mg. (in the future we intend to have every batch tested so we can give you a precise figure every time).

6* Coffee, brewed from grounds as reported by the Agricultural Research Service of the United States Department of Agriculture.

7* This number was derived from a range of teas; white, green and black. The results showed there was no observable trend in caffeine concentration due to variety of tea. Link here.

8* This study showed caffeine levels in green tea around 36.6mg/g (3.66%) per dry weight (which is the highest level we could find for any tea) Compared to 19.08mg/g (1.9%) of caffeine in Guayusa from this study. Looking at the lab-test results supplied from our own supplier, we have seen caffeine levels ranging between 1.9% and 2.4%, with an average of 2.1% from 7 different batches.

9* In this 2019 study.

10* Found in this interesting study. Section 2.2 and 3.3.1.

11* 3.5%-7.5% translates to 35-75mg/g, green coffee bean study

12* Comparison of cholorogenic acids in teas.

13* This study, although funded by AFS has this disclosure: “This research was sponsored by Applied Food Sciences Inc., the manufacturer of the JAVA.g and AMATEA extracts. Applied Food Sciences Inc. was involved in the research design, protocol formation, and review of the final manuscript, but QPS MRA (Miami Research Associates) was exclusively responsible for the execution of the clinical trial, analysis of the data and the interpretation of the results.”

14* See this summary of the study.

15* Article from


17* Article about histamine, side-effects are also listed in this article under the heading “what are the symptoms of histamine intolerance?”

18* Study investigating how histamine works in the body.

19* This article from Harvard Health Publishing.