Green Tea Side Effects

The Side Effects of Green Tea and How to Avoid Them

Various scientific studies prove that drinking green tea on a regular basis can bring multitudes of health benefits to your body. However, this natural healthy beverage can also cause some adverse side effects if taken excessively due to its caffeine content.

There are many people who are highly sensitive to caffeine. If they ingest excessive amounts of the said stimulant, they could suffer from serious health problems.

Green Tea and Caffeine

Green tea, in itself, is safe and healthy. However, due to it caffeine content it can cause some side effects to people who are sensitive to the said stimulant. People who drink seven or more cups of green tea each day expose themselves to an array of serious side effects such as nervousness, insomnia, headaches, irritability, and irregular heartbeat. Moreover, green tea’s caffeine content can also cause vomiting, dizziness, diarrhea, confusion, and even convulsion. If taken in high doses, green tea can be deadly.

Furthermore, green tea can also prohibit the absorption of iron from plant sources such as leafy green vegetables, nuts, peas, cereals, and the like. Green tea contains certain chemical compounds called tannins that prohibit the proper absorption of iron from dietary plant sources. However, iron from meat, especially red and dark meat, is still effectively absorbed by the body despite the presence of tannins.

It should be noted that the side effects enumerated earlier only occur when green tea is consumed excessively. For you not to experience the side effects mentioned above, it would be best for you to follow the recommendation of the International Society of Antioxidants on Nutrition and Health (ISANH), which is to keep your daily consumption of green tea to six cups.

Avoiding Green Tea Side Effects

You can still enjoy the benefits of green tea while avoiding its adverse side effects. Here are two effective ways to help you do so.

1) Opt for Decaffeinated Green Tea

As stated above, green tea’s side effects are primarily caused by its caffeine content. If you are highly sensitive to this stimulant, then it would be best for you to drink the decaffeinated version. However, make sure that the decaffeinated green tea you are going to buy undergoes a natural process known as effervescence. This decaffeination process utilizes carbon dioxide and water in eliminating the caffeine found in green tea. Best of all, effervescence does not use any chemicals.

2) Opt for Green Teas that Are Naturally Low in Caffeine

There are some green teas that are specifically manufactured to lower their caffeine content. For example, the caffeine content of Japanese Gyokura green tea is only 0.02%, a lot lower compared to black tea which has 0.05%. Another type of green tea that is naturally low in caffeine is Sencha green tea, which only has 0.015% caffeine concentration. But the green tea that has the lowest caffeine content is Japanese Houjicha green tea. It only has 0.008% caffeine!

By drinking decaffeinated green tea or opting for brands that are naturally low in caffeine, you can avoid the side effects of this healthy beverage and at the same time experience its wonderful health benefits.

Perfect Green Tea Blend Before Bed – High Antioxidants & Low Caffeine

If you are like me and enjoy having a cup of tea in the evening before bed, but don’t want to be wired and up all night, I have found a solution.

If I were to recommend a tea to you before bed that has reduced caffeine and still enough of the catechin antioxidants for the health benefits to still be there, I would say Salada Decaf Green Tea. It isn’t a super popular green tea, but it is great because I read a study that compared caffeine in green tea to catechin (antioxidant) concentration, and of all the decaf green teas, this one had one of the lowest caffeine contents (3.8mg/100mL) AND surprisingly it still maintained some of it’s antioxidants. This is great considering most decaf green tea’s don’t have the same antioxidant effects.

If you don’t care about the antioxidant effect and are just looking at which green tea has the absolute lowest amount of caffeine, I would recommend Celestial Seasoning Decaf Green Tea, as it only contains 0.7mg/100 mL of caffeine.

Keep in mind that regular, non-decaf green tea has between 20-80 mg/100mL of caffeine, so both of these options are great alternatives.

Caffeine in Green Tea

Caffeine in Green Tea vs. Coffee

Most people drink coffee in the morning because it tastes good and it has more caffeine to give you a more effective kick-start when compared to to green tea. Yes, it is true that coffee has more caffeine than green tea, and that one would have to drink three cups of green tea to equal the amount of caffeine in one cup of coffee, most avid tea drinkers find that it has a bit “too” much caffeine. Personally, coffee makes me jittery in the morning and I find tea has just the perfect amount of caffeine to wake me up…but that’s just me, you may be different. If anything, green tea has a more “refreshing vibe” to it, and is better after a meal to enhance digestion. Also, green tea is perfect in the evening for calming, without the harsh side effects on your sleeping patterns.

Did you know eight ounces of green tea contains about 35mg of caffeine? This is about half the amount of caffeine found in regular, black tea. However, this is still more significant than decaf tea, which has between 2 to 10mg of caffeine per cup. Even iced green tea has caffeine, about 15mg in a 16 oz. container. But many popular iced teas also have added sugar and calories.

Type of Caffeine in Green Tea

We are asking ourselves the wrong questions about “Caffeine in Green Tea”. Instead of asking “HOW MUCH caffeine is in green tea compared to coffee or black tea”, we should be asking “what kind of caffeine is in green tea” ? After all, people don’t find drinking coffee everyday effects their weight like they do when having green tea everyday for an extended period of time…this is partially attributed to the type of caffeine in green tea.

The caffeine in green tea is classified as methylxanthines. If you want me to get all science savvy on you, these caffeine methylxanthines can be broken down into two minor isomeric dimethylxanthines” called bromine and “thoephylline”. One study, published in the Journal of Frontiers in Bioscience (1), even found these two isomeric dimethylxanthines (fancy term for the type of caffeine in green tea), a mild stimulant attributed to the type of caffeine in green tea.

Caffeine in Green Tea and Health Benefits

Select studies even describe the use of caffeine in green tea to enhance mental activity, running performance and to treat apnoea and micraine headaches. I even came across a study that showed caffeine in green tea to implement this chemical called theophylline and theobromine in asthma and bradycardia treatments. How neat is that?!

Nature truly does provide us with everything necessary to live a long and healthy life. The benefits of green tea are just endless.

Want to learn more about green tea benefits?

Subscribe to our mailing list.


(1) Anaya, A. L., Cruz-Ortega, R., & Waller, G. R. (2006). Metabolism and ecology of purine alkaloids. Front Biosci11, 2354-2370.