Green Tea Extract Side Effects

green tea extract side effects

At the end of the summer season last year, we promoted green tea extract in a detailed blog post heading in to the colder months.  People tend to run out of energy and put on a few extra pounds when the winter months come around so there is a noticeable increase of green tea consumption throughout the nation heading in to October and November.  Sales seem to plateau and pick back up around April, as the warmer months are coming back.  The change in season and green tea extract consumption rates relate so closely because people are first, panicking and trying to prevent the weight gain that seems to come with winter, and then second, trying to get back in to shape for bathing suit season!  Well, it’s that time of year for the latter and in preparation for that, we want you to be aware of the potential green tea extract side effects…

Green Tea Extract Side Effects?  What Side Effects?

We know… it’s almost hard to believe that something so natural, void of human synthetics, would come with a plethora of side effects [1].  I mean, seriously.  When was the last time you stopped in a Starbucks, ordered a tea, and stopped for a second to think about how this tea could negatively affect you?  You haven’t because that would be insane.

The truth is, high levels of green tea consumption and green tea extract CAN have undesirable side effects.  Let’s take a look at the 5 most worrisome first!

  1. It’s entirely possibly to overdose on caffeine.  Green tea extract contains high levels of caffeine, so we need to understand that moderation is key [2].  A fatal dose of caffeine is between 10 and 14 grams.  That’s quite a bit of green tea extract since one capsule typically contains 300mg to 600mg,
  2. Infant Fatality. Pregnant women should not consume anything more than a low level of caffeine.  It would only take a few grams to create a toxic environment for an unborn child.  Nursing mothers also need to be aware that the caffeine can pass through breast milk.
  3. Heart Conditions. Green tea extract can cause irregular heartbeats and force people with weak hearts in to cardiac arrest.  It’s best to avoid products with high levels of caffeine if you have known heart issues [3].
  4. High blood pressure. This sort of goes hand in hand with #3.  If you’ve struggled with blood pressure in the past then it’s best you look for your antioxidant supplementation from some other means… especially if you’re on blood pressure medication [4].
  5. Liver disease. Unsurprisingly, the liver rounds up our list of top 5.  Almost every supplement on the market effects the liver negatively.  If you’ve got a weak liver from previous abuse, avoid green tea extract supplementation [5].

Being honest, it’s super unlikely you’re going to experience any of those nasty side effects.  The more common, less concerning side effects include headaches, nausea, and insomnia but even those are fairly uncommon or pass within just a few days of supplementation, once your body is used to it.  If you have more questions or concerns about your specific scenario, it’s always going to be best to reach out to your doctor.  Make sure you do some more research so that you understand it’s not all doom and gloom [6]!


  1. Sabu M Chacko,corresponding author1 Priya T Thambi,1 Ramadasan Kuttan,2 and Ikuo Nishigaki1
    Beneficial effects of green tea: A literature review
    Chin Med. 2010; 5: 13.
    Published online 2010 Apr 6. doi: 10.1186/1749-8546-5-13
  2. Dulloo AG1, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J.
    Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.
    Am J Clin Nutr. 1999 Dec;70(6):1040-5.
  3. Pon Velayutham, Anandh Babu, and Dongmin Liu*
    Green Tea Catechins and Cardiovascular Health: An Update
    Curr Med Chem. Author manuscript; available in PMC 2009 Sep 22.
    Published in final edited form as:
    Curr Med Chem. 2008; 15(18): 1840–1850.
  4. Xiaoli Peng,1,2,3 Rui Zhou,2,3 Bin Wang,2 Xiaoping Yu,1 Xiaohong Yang,1 Kai Liu,a,2 and Mantian Mib,2
    Effect of green tea consumption on blood pressure: A meta-analysis of 13 randomized controlled trials
    Sci Rep. 2014; 4: 6251.
    Published online 2014 Sep 1. doi: 10.1038/srep06251
  5. T Isomura,1,2,3,4 S Suzuki,3,* H Origasa,4 A Hosono,3 M Suzuki,1 T Sawada,1 S Terao,1 Y Muto,1 and T Koga1
    Liver-related safety assessment of green tea extracts in humans: a systematic review of randomized controlled trials
    Eur J Clin Nutr. 2016 Nov; 70(11): 1221–1229.
    Published online 2016 May 18. doi: 10.1038/ejcn.2016.78
  6. Sabu M Chacko,corresponding author1 Priya T Thambi,1 Ramadasan Kuttan,2 and Ikuo Nishigaki1
    Beneficial effects of green tea: A literature review
    Chin Med. 2010; 5: 13.
    Published online 2010 Apr 6. doi: 10.1186/1749-8546-5-13
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