Woman Drinking Tea

Caffeine in Coffee and Tea: All You Need to Know

Posted by Stephany Morgan

After my post the other week about the health benefits of tea, there was quite a lot of interest in the difference between caffeine in tea vs in coffee. So, here's everything you need to know about caffeine!

Caffeine may be the most misunderstood molecule that we regularly consume. It is both adored and vilified, is extremely addictive, is consumed by over 90% of Americans every day, and studies have shown it can have an enormous range of effects. For something so potent, though, we tend to consume it without a lot of thought.

So what is caffeine anyway?

Caffeine (1,3,7 trimethylxanthine) belongs to the family of heterocyclic compounds called purines. These are a type of plant chemical considered “alkaloids”. Alkaloids are nitrogen bases with a diverse range of functions. Familiar alkaloids include drugs such as caffeine, morphine, ephedrine, and nicotine.


Caffeine Tea Beakers


Is caffeine really a drug? How much is safe? How much caffeine is in a cup of coffee or tea?

Caffeine is a stimulating substance that has addictive properties so yes, it is a drug. It is often treated carelessly, which is why we sometimes see medical scares in regard to energy drinks, caffeine pills, and other supplemental agents aimed at mental stimulation. The issue is that caffeine can be overdosed (extremely unlikely where tea or coffee is concerned).

But, the point of this article is to help bring light to its function, not worry you! When taken in appropriate amounts it is entirely benign.

The Mayo Clinic recommends no more than 400 milligrams of caffeine daily, for healthy adults. It is best to consume these amounts in divided doses, to avoid negative side effects. To give you some idea of how much that is, a normal mug of black coffee has around 95 mg of caffeine, yerba mate has ~90mg, matcha has ~70mg, and green tea has roughly 35mg.

Though you’ll see below that there is a huuuuge range of caffeine levels possible in different types and preparations of tea!


Types of Tea


How does caffeine work? How fast does it kick in?

Caffeine binds to adenosine receptors in the brain. It actually slips in and takes the place of adenosine, circumventing the original CNS depressant activity of the neurotransmitter and stimulates the nervous system instead. Caffeine also promotes other neurotransmitter release, which further act to stimulate the brain and nervous system. It increases the response of excitatory neurotransmitters, and activates the sympathetic nervous system. Additionally, it increases beta waves in the brain, and decreases the slow wave brain activity. 

Caffeine stimulates the medullary, vagal, respiratory, and vasomotor areas in the brain.

Beyond promoting wakefulness and alertness, it also improves coordination! Pretty cool, eh?

Caffeine in coffee kicks in after about 10 minutes of consumption, but the peak caffeine concentration in your blood stream is reached after around 45 minutes. As a good rule of thumb, the level of caffeine in your body halves every six hours, meaning it sticks around for a while. However, a lot of people find they ‘crash’ about 90 minutes after drinking a cup of coffee.

Caffeine in tea also kicks in around 10 minutes, but reaches peak concentrations after around 60 minutes due to the L-theanine. The L-theanine slowly releases the caffeine, preventing a caffeine crash and aiding sustained focus and concentration over 2-6 hours depending on the study. More details about L-theanine below.

Note that caffeine always kicks in around 10 minutes after consumption, whether it's in tea, coffee, sodas or energy drinks.

Many Coffee Lattes


Is it possible to build a caffeine tolerance?

Caffeine WithdrawalYes, and as the tolerance increases, the more of the substance a person needs to experience those feelings of alertness. Caffeine can also exacerbate adrenal fatigue (a form of chronic exhaustion common in the West where overworked, chronically stressed people abound). As the need for more increases, a dependence can form. The most common caffeine withdrawal symptom is a pounding headache and, as I’m sure we’ve all encountered, irritability. When people say that caffeine actually helps their mood, the mood improvement they are experiencing is simply a reaction to the reintroduction of caffeine to the system.

For people who want to wean themselves off coffee, yerba mate and green tea are good options: yerba mate has slightly less caffeine than coffee, and green tea has about half to a third the amount. Taking it slowly rather than going cold turkey is also a given!




Caffeinated Drinks


Caffeine without coffee: What are some common sources of caffeine?

Some of the most commonly known items containing caffeine are beverages. The most obvious are:

Natural sources of caffeine:


  • Teas (‘true’ teas from the Camellia sinensis plant plus a few herbal teas, such as yerba mate, yaupon and guayasa)
  • Coffee (generally ~95mg/8oz cup, though it varies by preparation method and beans)
  • Chocolate (~20mg/oz)


Other sources of caffeine:


  • Soft drinks also generally have caffeine added to them, such as Mountain Dew (55mg/can)
  • Energy drinks contain a mixture of stimulating herbs, (usually synthetic) energizing B-vitamins, and added caffeine. A can of Red Bull, for example, has 80mg of caffeine.
  • Caffeine pills: the Wild West of caffeine, and not something I would recommend for health or safety for many different reasons. 


The University of Utah has an interesting table of caffeine quantities by drink if you're curious!





Tea vs Coffee


So, what’s the difference between caffeine in coffee and tea?

Although the molecule is the same, caffeine works quite differently in coffee vs tea:



Caffeine in coffee is an unsupervised “wild child”. And just like a kid who has had too much sugar, coffee-caffeine amps you up by stimulating the nervous system, increasing blood flow and alertness (even to the point of giving you jitters), and when it is all used up you come crashing down.

Beyond that, caffeine inhibits relaxing adenosine and takes its place instead, creating stimulation and excitatory responses in the brain. In addition to that, it is a vasoconstrictor - meaning it constricts your blood vessels and causes a rise in blood pressure. Caffeine is also associated with causing anxiety and restlessness.



To put it simply, caffeine in tea is under supervision by an amino acid called L-theanine. This amino acid is unique to tea and does double duty by allowing caffeine to work, all-the-while mitigating its less desirable effects.

Theanine increases the alpha wave band in the brain- the “brain waves” associated with relaxation, calmness, alertness, flow of thought, and some forms of meditation. By doing this, it prevents caffeine jitters, and participants in a study reported less caffeine crash side effects such as headache and fatigue.

Furthermore, it prevents the vasoconstriction caffeine causes, thereby preventing rising blood pressure! 


Range of Loose Leaf Tea Types


Is all tea caffeinated? Which teas have the most caffeine?

Teas vary in amount of caffeine based on the processing of the leaves. Although there are several classes of tea (which all come from the same plant) they are all “made” differently by being subjected to various amounts of sun or shade, oxidation, heat, and in rare cases, fermentation.

Additionally, caffeine content, like other phytochemicals, can vary within the plant based on environmental factors, which is partially why there are only approximate amounts of caffeine listed in milligrams per tea type. A useful rule of thumb, though: the younger the tea leaf, the higher the caffeine content.


White Tea

White tea is the least oxidized. There are several types of white tea (just as there are green and black teas), and they can contain anywhere from 6-75 mg of caffeine! The white tea called Silver Needle is made from the buds, or “tea tips” of younger leaves.

These tea bud white teas generally have a higher caffeine content than white teas made from more mature leaves. Silver Needle has a lot of caffeine, whereas Pai Mu Tan, a white tea made using older leaves, will have a lesser amount.


Green Tea

Things can get a little hairy, here. Powdered green teas (and matcha) are consumed whole, unlike green teas which are steeped and strained. Matcha can contain up to 70mg of caffeine per teaspoon of powder.

Green teas can contain between 7-40mg of caffeine per 8oz depending on quality, leaf size and brewing time. Green teas with lower levels of caffeine include Genmaicha, Gunpowder and Hojicha.

Greens at the upper end of the caffeine spectrum include matcha and Gyokuro, as both these teas are shaded (literally placed under shade clothes for days to weeks before harvesting) which tricks the plant into producing a lot more caffeine.


Black Tea

Black teas vary just as much as green teas. On average, an 8oz cup contains about 22-25mg of caffeine, though it has been reported as containing amounts as high as 40-42mg (for a 3 minute steep).

Often, though, black teas brew up with more caffeine than greens, because the leaves are ground into dust and packed into tea bags. When brewed, almost all the caffeine in the leaf is extracted into the tea liquor, plus black tea should be brewed with boiling water which also extracts the most caffeine.


For brewing instructions on how to make the perfect cuppa, take a look at our "Ultimate Guide to Brewing Tea and Tisanes" blog post. There's a lot more information there!


Pouring Out Tea


Is it possible to decaffeinate my tea at home?

The short answer: No.

The long answer: There are many home remedy myths that circulate in the tea world and crop up every once in a while, and this is one of the big ones. The myth says that if you quickly brew your tea for 30 seconds and discard that liquor, you’ve discarded all the caffeine, and can then re-brew your leaves without worry. However, this is simply not true. Caffeine actually takes a while to come out of the leaves, with only ~20% of the caffeine being extracted in the first 30 seconds.

Instead, to adjust caffeine levels at home, remember these rules:


  • Short brewing time + low water temperature = less caffeine
  • Long brewing time + high water temperature = more caffeine
  • The smaller the leaves, the more surface area (i.e. teabags) = caffeine will be extracted quickly
  • The larger the leaves, the less surface area (i.e. loose leaf) = caffeine will be extracted slowly


If you’re drinking ‘true’ tea, you’ll always have some caffeine in your drink. Even decaffeinated teas have some caffeine – the only way to ensure a caffeine-free brew is to make a herbal tea instead, such as rooibos or honeybush.


Caffeine Facts


Fun caffeine facts:

  • Even decaf coffees and teas have caffeine; they contain about 3-18 mg
  • Chocolate contains caffeine (dark chocolate contains more than milk chocolate)
  • Yaupon, an herb related to Yerba Mate, contains about the same amount of caffeine and is the only caffeine-containing plant native to North America
  • The caffeine levels in tea increase the longer it is brewed for (however, it can also become very bitter, so beware!)
  • Caffeine doesn’t degrade over time, so your iced tea from a few days ago still has a caffeine kick. However, antioxidants DO degrade – over a few hours only.
  • Tea leaves technically have more caffeine in them than coffee beans (but far less caffeine comes out during brewing, making tea lower in caffeine consumed than coffee)
  • The amount of caffeine per serving will influence how quickly it takes to notice its effects (high doses: 300-400 mg) will be more noticeable due to the large influence on the neurochemical receptors in the brain
  • Tea contains less caffeine than coffee or energy drinks, generally, so the noticeability of the caffeine may be more subtle, and therefore may seem to take longer to kick in (dose-dependent relationship), however the rate of effect of the caffeine remains the same and really comes down to perception
  • Differences in gene expression can influence how quickly caffeine takes effect in the body. Some people find caffeine makes them sleepy and others find a cup at 6am will keep them awake for days!
  • Body composition, liver function, a full or empty stomach, and age are also factors which influence how soon caffeine will take effect, and how noticeable its effects are


Tea for Studying


A Note From The Herbalist...

Okay, I admit… I love coffee. But, I also love tea! I honestly cannot choose a favorite.

When I was in college, I used to say that coffee was my morning drink and tea was my afternoon and evening drink. The reason I did this was because I was taking a full load and working, so like the typical overworked college student I needed energy… but I also needed to get some good quality sleep, which did not happen if I drank coffee post-dinner. It was a bad habit I needed to break - so I switched to tea and it made such a difference!

It was neat to learn that caffeine in coffee affected brain function related to sleep differently than that of caffeine in tea. As I mentioned earlier, L-theanine is present with caffeine in tea. Caffeine alone reduces your slow wave sleep (the deepest part of REM needed for overall quality of sleep), but when combined with L-theanine, this action is minimized, resulting in better sleep and less fatigue the next morning.

Although I loved drinking coffee during my school days, I no longer drink it - I opt for teas, Yerba Mate, or stimulating herbal adaptogens like Moringa for energy, instead! 


The best green and herbal teas to get you started...

If you are looking to either cut out or reduce the amount of coffee you drink, these teas are the best place to start:



 'The Purist' Green Yerba Mate - Matcha AlternativesRoasty Toasty Mate - Matcha AlternativesDelicate Fuji Sencha Organic Green Tea - Matcha AlternativesSuperior Moringa Tea Powder - Matcha Alternatives

    Explore our Tea Science & Lifestyle blog |

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    And of course... All of the information regarding the herbs, botanicals, minerals, vitamins, etc., is information drawn from traditional use data or academic research and should be regarded as such. If you, the reader, has a health or medical concern, please consult your healthcare professional. The information found here is not meant to diagnose, treat, prescribe or cure and has not been evaluated by the FDA. The information here is for educational use only.


    Caffeine in Coffee and Tea References and Further Reading

    Caffeine Chemistry

    Editors of Encyclopaedia Britannica. Alkaloid: Chemical Compound. Encyclopaedia Britannica. Accessed September 23 2019.

    1,3,7-trimethylxanthine. (n.d.) Gale Encyclopedia of Medicine. (2008). Accessed September 23 2019.

    Science Direct. Purine Alkaloid (Summary of Literature). Science Direct, 2019. Accessed September 23 2019.

    US NCBI. PubChem Database. Caffeine, CID=2519. US National Center for Biotechnology Information. Accessed September 23 2019.

    Science Daily. Caffeine. Science Daily. 2019. Accessed September 23 2019.
    Coffee and Health. Sources of caffeine. ISIC the institute for scientific information on coffee, 2019. Accessed September 23 2019.

    Smith, S. Caffeine. Chemistry Encyclopedia, 2018.  Accessed September 23 2019.

    Mayo Clinic Staff. Caffeine: How much is too much? Mayo Clinic - Healthy Lifestyle, Nutrition and healthy eating. 2017. Accessed September 23 2019.

    Mandal, A. What is Adenosine? News-Medical.Net, 2019. Accessed September 23 2019.

    drug. (n.d.) Farlex Partner Medical Dictionary. (2012). Accessed September 23 2019.

    Crane, M. Yaupon, the Only Caffeine Source Native to the U.S., Has Potential to Explode. Nutritional Outlook. 2015. Accessed September 23 2019.

    Healthline. Medulla Oblongata. Healthline. Accessed September 23 2019.

    Brainworks Neurotherapy. What Are Brainwaves? Brainworks Neurotherapy. Accessed September 23 2019.

    Villazon, L. How long does caffeine take to kick in? BBC Focus magazine. Accessed November 25 2019.


    Caffeine in Tea and Coffee

    Goodwin, L. How Much Caffeine Is in White Tea? The Spruce Eats, 2019. Accessed September 23 2019.

    Caffeine Informer. Matcha Green Tea. Caffeine Informer. 2019. Accessed September 23 2019.

    Yoto A, Motoki M, Murao S, Yokogoshi H. Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. J Physiol Anthropol. 2012;31(1):28. Published 2012 Oct 29. doi:10.1186/1880-6805-31-28. Accessed September 23 2019.

    Nobre AC, Rao A, Owen GN. L-theanine, a natural constituent in tea, and its effect on mental state. Asia Pac J Clin Nutr. 2008;17 Suppl 1:167-8. Accessed September 23 2019.

    Caffeine Informer. Green Tea. Caffeine Informer. 2019. Accessed September 23 2019.

    Witherby, J. Caffeine and L-Theanine: The Best Combo for Energy. Health Via Modern Nutrition, 2019.  Accessed November 25 2019.

    Kuakini Health System. Caffeine: America's Most Popular Drug. Kuakini Health System. Accessed November 25 2019.

    Schmidt, A., Hammann, F., Wölnerhanssen, B. et al. Green tea extract enhances parieto-frontal connectivity during working memory processing. Psychopharmacology (2014) 231: 3879. https://doi.org/10.1007/s00213-014-3526-1. Accessed November 25 2019.

    Simon P. Kelly, Manuel Gomez-Ramirez, Jennifer L. Montesi, John J. Foxe, L-Theanine and Caffeine in Combination Affect Human Cognition as Evidenced by Oscillatory alpha-Band Activity and Attention Task Performance, The Journal of Nutrition, Volume 138, Issue 8, August 2008, Pages 1572S–1577S, https://doi.org/10.1093/jn/138.8.1572S. Accessed November 25 2019.

    The Tea Table. An Update on Tea and Caffeine. The Tea Table.  Accessed November 25 2019.

    David J. White, Suzanne de Klerk, William Woods, Shakuntla Gondalia, Chris Noonan, Andrew B. Scholey. Anti-Stress, Behavioural and Magnetoencephalography Effects of an l-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial. Nutrients. 2016 Jan; 8(1): 53. Published online 2016 Jan 19. doi: 10.3390/nu8010053. Accessed November 25 2019.

    Tea Class. The Truth About Caffeine: Lesson #12. Tea Class by Adaggio. Accessed November 25 2019.

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    • Hi, thank you for collecting and synthesising all this useful info about caffeine for us. You have taken so much time, care and effort. I look forward to sipping your teas. I love your website!


    • Thank you for your lovely comment Patricia!! Really happy you enjoyed the article, and looking forward to hearing what you think about your new teas! :-D

      Elizabeth, Matcha Alternatives

    • Very nice article! I read it while drinking Pu‘ehr at the Beijing Airport :) . I appreciate the link to the references, it is nice to be able to do further research. Looking forward to trying my new teas. ;)

      Patricia Vidal Galvez

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