Hi Ritu,
Not only bru but all coffees have some side effects but that would be only when There are some serious things about harmful effects of excessive coffee intake. Not about caffeine, but coffee. It has irritating effect on gastric mucosa and can lead to development of ulcers. Else, people that are heavy coffee drinkers may develop vitamin b1 insufficiency. Caffeine interacts with absorption of some nutrients in small intestines. The only healthy way to treat tiredness and fatigue is to have rest. Also, long term coffee drinkers often develop liver function disorders.