Caffeine is harmful when taken excessively. Negative health effects of caffeine include difficulty in sleeping, increased anxiety, restlessness, trembling muscles and a rapid heart rate.
People typically experience the side effects of caffeine when they consume more than 500 milligrams per day. However, certain people are more sensitive to caffeine and experience undesirable side effects after consuming one cup of coffee. Men are affected by caffeine more easily than women. Some medications have adverse interactions with caffeine. On the other hand, caffeine has its benefits when consumed in the right amount. These include increased attention and alertness, reduced fatigue levels, and improved wakefulness.