Tea has been in use by humans for over 500,000 years. Of the three main types of tea, green tea has been shown to have many healing qualities when it comes to the human body. Its high antioxidant content (higher than the other forms of tea) has been researched and used to help with cancer, atherosclerosis, high cholesterol, liver disease and a plethora of other maladies. But not everything about green tea is beneficial and there are certain things of which anyone who's thinking about trying it should be aware.
Green tea is high in caffeine. Drinking too much green tea will have the same effects on the body as those of coffee and highly caffeinated soda. With the consumption of green tea you will feel the same effects as those associated with caffeine. At first the tea can cause alertness but over-consumption could lead to irritability, bouts of insomnia, irregular heart palpitation and dizziness. You can also overdose on the caffeine in green tea which may result in nausea, vomiting and stomach cramps.
While certain studies have shown that green tea actually accentuates the effectiveness of certain chemotherapy drugs (doxorubicin and tamoxifen) in fighting cancers, there is also a negative side effect. Green tea will actually stimulate a gene in prostate cancer cells that will make the virus more difficult to fight with radiation treatment.
Green tea has also been linked to severe side effects when used in concert with a variety of medications used to treat serious maladies. For instance, if you are taking anything with phenylpropanolamine, a common ingredient in over-the-counter cough medications, drinking green tea can cause mania and a rapid increase in blood pressure. This is also the case with many of the drugs taken to combat depression.