Side effects of matcha green tea may include stomach upset and constipation. This tea has a high caffeine content, and the National Institutes of Health recommends against drinking more than five cups a day.
In large quantities, matcha tea, along with other green teas, can also cause insomnia, heart palpitations and dizziness. The caffeine in the tea can cause these effects, as well as diarrhea and aggravation of irritable bowel syndrome.. Green teas can interact with some medications, particularly those that control blood pressure and heart rhythms. It may not be safe for women who are pregnant or breastfeeding, states the National Institutes of Health.