I want to know the side effects of caffeine as a result of excess coffee consumption?

Many! Caffeine stimulates the central nervous system. It can raise blood pressure. The known side effects include irritability, nervousness and anxiety, digestive problems, an increase in heart rate and breathing, chest pain, dizziness, headache, tinnitus (ringing in the ears) and fatigue. Some people some people just get the jitters. Excess consumption is sometimes associated with depression.