When we usually talk about green tea, we always tend to emphasise how healthy and good it is for us, but most of us are unaware of the side effects of green tea. Green tea is definitely a healthy option but like everything it has its side effects too, some are mild while some are the  areas of concern and thus it is very important for you to know them before you head for another cup of green tea.
Caffeine effect:

Though green tea has lower caffeine content than its counterparts like coffee and normal tea but it still has caffeine. Excessive consumption even if it is green tea can lead to restlessness, palpitations, difficulty in sleeping, anxiety, irritability, increased heart rate, and elevated blood pressure. People with low tolerance to caffeine might notice these effects more strongly. This is one of the major effects of green tea. You can easily counter this problem by either drinking decaffeinated green tea or switching to a better quality green tea and look for the one that contains higher levels of theanine. Theanine is a compound which has a calming effect on the brain and reduces these effects of the caffeine.

Upset stomach and nausea:

Green tea contains tannins which stimulate the stomach to secrete more acid. This might prove to be an issue for people who have a history of peptic ulcer or acid reflux problems and thus leads to stomach upset or nausea. It is also advisable to refrain from consuming green tea during diarrhoea as tannins tend to worsen it. This side effect can be countered by making sure that the green tea is consumed after a meal and not on an empty stomach.

Iron deficiency:

The tannins in green tea prevent blood from absorbing certain nutrients. One key concern in this case is reduction in absorption of iron. Studies show that excessive consumption of green tea leads to reduction in absorption of iron in body by up to 25 %. To counter this side effect consume green tea only between meals or add lemon to it. Lemon reduces the effect of tannins on the body.

Green tea during pregnancy:

Doctors’ advice against taking any form of caffeine during the early months of pregnancy as studies have linked excess intake of caffeine to neural birth defects. As green tea also has caffeine content it has similar side effect as coffee or other form of tea.

Green tea and medication:

Green tea like any other tea can interfere and cause reactions when it interacts with certain medications. It is always advisable to consult your doctor before if you are on some medication. You can make sure that you don’t consume green tea for around two hours after taking any medicine.


This is considered to be one of the severe side effects of green tea. Some studies show that drinking green tea can increase the amount of calcium that is flushed out from the body with urine. Though the probability of this only increases if amount of green tea consumed is such that intake of caffeine becomes more than 400 mg per day (approximately 4-5 cups of green tea) and the same can be countered by taking calcium supplements.

Green tea side effects are quite rare and its benefits outweigh its harmful effects. Also you might notice that most of these side effects occur if green tea is consumed in excess so drinking 2–3 cups of green tea per day is fine, but more than that may lead to some undesirable effects and problems.