People consumed tea leaves steemed in boiling water as many as 500,000 years ago. India and China were among the first countries to cultivate tea. Today, millions of people drink tea around the world and studies are now suggesting that green tea (Camellia sinensis) in particular has many health benefits. Green tea has the highest polyphenol content while black tea has roughly two to three times the caffeine content of green tea. take any healthy food excessively; it is likely to turn into a poison. Green tea contains active substances that can trigger side effects and interact with other supplements or medications. People should take green tea and green tea extracts with care to get its beneficial effects and to avoid its side effects. People with heart problems, kidney disorders, stomach ulcers, and psychological disorders (particularly anxiety) should not take green tea. Also pregnant women should avoid green tea.Key word:Green tea, green tea toxicity, green tea side effects, uses of green tea.