The effects of this stimulant differ for each individual, depending on factors such as the quantity consumed, whether that quantity was taken all at once or over time, and the tolerance level the user has developed to caffeine.
Most people develop a tolerance quickly.
Caffeine may increase blood pressure, raise blood cholesterol, and cause irregular heartbeats for those who are unaccustomed or sensitive to its use. In the United States, coffee consumption represents 75 percent of all caffeine consumed, soft drinks 15 percent, and 10 percent from tea, chocolate, and medication. Caffeine can show up in common cold medications, allergy pills, diet pills, headache remedies, and even sometimes as a flavoring agent in baked goods, frozen desserts, and puddings. But caffeine isn't all bad. It temporarily reduces muscular fatigue, increases speed and efficiency of mental and manual tasks, and can even stimulates creativity.