Serious Side Effects Of Green Tea?

There are few known serious side effects of green tea. Here are the 8 worst case scenarios for the truly cautious.

Stomach Upset

Caffeine can cause stomach upset. Tea also contains other compounds that can cause indigestion by stimulating the production of gastric acid.

Tea can be a problem for those prone to heartburn and stomach ulcer. Heartburn results when gastric acids rise up and spill into the esophagus, causing irritation.

Medication Interaction

Green tea, like any other beverage, can interfere and interact with certain medications. As a safety precaution, avoid drinking tea for at least 2 hours after taking medications.

Supplement Overdose

This is perhaps the most serious side effect of green tea.

Take any healthy food excessively, and it is likely to turn into a poison. Green tea supplements have been found to kill dogs at high doses.

"Up to 10 small cups of green tea a day is fine. Problems are likely in people who take supplements, which can contain up to 50 times as much polyphenols as a single cup of tea," said Yang from the State University of New Jersey.


Much controversy surrounds fluoride. We get most of it from drinking water. Low levels of fluoride help prevent dental caries, but a high level of fluoride is harmful to the teeth and bone.

In a 2005 study conducted by Washington University, a middle aged woman diagnosed with skeletal fluorosis drank 17 to 33 cups of instant iced tea a day, double-strength, because of the hot weather.

Iron deficiency

There are two kinds of dietary iron: heme and non-heme.

Heme iron, found in meat, fish and poultry, is absorbed by our bodies very efficiently.

Non-heme iron, found in flours, cereals, and fortified grain products, is more difficult to absorb.

A study published in the March 2001 edition of the American Journal of Clinical Nutrition reports that green tea extract reduces absorption of non-heme iron by 25%.

Neural Tube Defects

Green tea contains catechins, caffeine and tannic acids. All 3 substances have been linked to pregnancy risks.

Studies suggest that drinking large amounts can cause neural tube birth defect in babies.

Nevertheless, moderate consumption is considered safe.

If you are pregnant, and especially in the first trimester, take a break. Beware of this serious side effects of green tea. Stop your tea intake completely.

Menopausal Symptoms

In preliminary research, green tea has been associated with a decreased level of estrogen in the body. It is not clear if it may aggravate hot flashes.

Caffeine Intolerance

For those who are sensitive to caffeine, here are the symptoms to watch out for: restlessness, irritability, sleeping problems, tremor, heart palpitations, loss of appetite, upset stomach, nausea, frequent urination and skin rash.

Caffeine may cause problems to those suffering from heart problems, high blood pressure, diabetes, psychological disorder, hyperthyroidism and liver disease.

Finally, if you have any other health concerns, play it safe. Consult with your health adviser before drinking green tea.

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Medline Plus: Green Tea (Camellia sinensis).

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