What Are the Effects of Drinking Too Much Green Tea?

K. Testa

Drinking too much green tea can have several adverse health effects, ranging from mildly irritating symptoms to serious medical complications. Aside from the common side effects of ingesting caffeine, it can also result in potentially dangerous interactions with some medications. It is important to note that for certain people, extremely high doses of caffeine can be fatal. Most medical professionals define too much as being five cups or more of green tea per day.

Green tea.
Green tea.

Like other products that contain caffeine, too much green tea can cause the following common reactions: irregular heartbeat, headache, sleeping difficulties, and anxiety. One serious complication of drinking excessive amounts of green tea is the hindrance of iron absorption, potentially making existing anemia or bleeding disorders more dangerous. Furthermore, high blood pressure can reportedly be made worse in people who already suffer from the condition.

Five cups or more of green tea per day is considered too much.
Five cups or more of green tea per day is considered too much.

Too much green tea can also lead to interactions with certain medications, either by hindering their absorption or by heightening their effects. For example, consuming large quantities of green tea is believed to slow down the effectiveness of warfarin, an anticoagulant. People are also generally advised to avoid combinations of stimulant drugs, such as amphetamines and caffeine.

Too much green tea can cause an irregular heartbeat.
Too much green tea can cause an irregular heartbeat.

While green tea toxicity may be a concern for some people, it is typically considered more of a risk for those who take green tea supplements. Some studies have found that the high doses of polyphenols in green tea can lead to conditions such as kidney damage and liver disease. The list of touted benefits of green tea extract is extensive and includes helping with numerous medical conditions, such as bone loss. For some people, though, weak bones or osteoporosis may actually result from drinking too much green tea, as it can result in an increased loss of calcium through urine. Although the focus has been more on green tea extract as potentially harmful, many doctors prefer to warn people not to consume too much green tea in any form.

Too much green tea can exacerbate high blood pressure symptoms.
Too much green tea can exacerbate high blood pressure symptoms.

Certain members of the population, such as pregnant or breastfeeding women, might also want to be careful when consuming green tea. For instance, some research has found negative outcomes, such as birth defects, associated with drinking too much green tea either before becoming pregnant or during the first trimester. Anyone concerned about the issues associated with green tea safety should discuss them with a health care provider, who can usually also offer ideas for alternatives to green tea, including caffeine-free beverages.

In some people, drinking too much green tea can lead to osteoporosis.
In some people, drinking too much green tea can lead to osteoporosis.

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Discussion Comments


I've been drinking green tea on a regular basis, four times a day (minus a day or two here and there but not often) for about nine years now and it has done nothing but helped me with anxiety and depression, made me feel extremely healthy, helped with sinus problems, made my skin look healthy and vibrant, etc. I couldn't possibly imagine my life without green tea now. I think it's a miracle!

The negative things they say about green tea doesn't apply to everyone because for me it's been nothing but positive effects!


I sometimes have indigestion when I have too much green tea. I think it happens if I have just had a meal or if I am hungry. I never have problems when I have it with a small snack, some biscuits or a cookie with it.

I think when it comes to the effects of green tea or any other herb, it's probably best to test it out in small amounts. We all have different physical tendencies. So it might effect some of us more. I've always had a sensitive stomach, that must be why it upsets my stomach sometimes.


I saw that green tea had caffeine when I read the label on the box. One brand also has information on it's label about how much caffeine green tea has compared to other teas. Like black tea has the most caffeine, second is green tea and third white tea.

We can determine which to have depending on this. I like having green tea during the day, for example, and white tea at night so I don't have trouble sleeping.


It's good to know more about green tea. I didn't realize that green tea has enough caffeine to effect sleep and cause anxiety. I have been drinking green tea thinking that it is like herbal tea. I even thought that it might help with PMS symptoms.

I usually have three cups per day. I had noticed though that my anxiety medication doesn't seem to work too well when I have it at the same time as green tea. It makes sense now. I'm going to be more careful from now on.

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