Excessive use of tea can result in increased blood pressure, heart rate as well as constipation. There are numerous varieties of tea, such as black tea and green tea, which are the products of the Camellia sinensis plant steeped in water, and rooibos tea, which is derived from the Aspalathus linearis plant.
Side-effects are usually associated with black tea due to the level of caffeine it contains. Studies of black tea's side effects specifically are limited but the presence of caffeine can result in multiple reactions. Caffeine is a stimulant and, as such, can hinder sleep patterns through insomnia. Stimulation of the central nervous system can affect adults, children and infants. Nursing infants can also be affected by the mother's intake of caffeine.
Caffeine is also a diuretic, increasing urine, and possibly exacerbating incontinence concerns.Caffeine can have further effects on the stomach, increasing the production and severity of stomach ulcers. The tannin found in tea has been known to cause constipation. Caffeine in certain doses can increase blood pressure and heart rate although people who regularly consume caffeine do not seem to show these symptoms. Blood sugar may also be affected by caffeine intake with an increase noted in some cases. Caffeine has also been known to cause skin rashes in the case of intolerance and excessive use can stain teeth.
According to Healthline, high dosages of caffeine can be dangerous with symptoms of anxiety, agitation, delirium, psychosis or detrussor instability noted. Conception may also be hindered with high concentrations of caffeine.