Studies regarding side effects associated with green tea (Camellia sinensis) are limited in scope, yet researchers are aware that some side effects do exist. Although there is less caffeine in a glass of green tea as compared to a cup of coffee, drinking several glasses of green tea a day can cause side effects related to the caffeine content such as anxiety, insomnia and an increase in blood pressure. Other common side effects include upset stomach, diarrhea and constipation.
- Those who suffer from anemia should limit the intake of green tea as it can block the absorption of iron by the body.
- Hypertension, seizures, arrhythmia and signs of allergic reaction should be reported to a physician immediately.
- There have been reports of a possible link between green tea capsules and liver damage, although a link has not been clearly established.