For those with caffeine sensitivity or high consumption levels of green tea, there may be some caffeine side effects.
In general, green tea has less caffeine than other tea types. However, some types of green tea (such as matcha green tea) can have more caffeine than your typical black tea or even an espresso. However, excessive consumption of green tea can cause restlessness, heart palpitations, difficulty sleeping, anxiety, irritability, increased heart rate and elevated blood pressure. People with caffeine sensitivity are more susceptible to these side effects.