Like all stimulants, caffeine raises blood pressure and its effects range from mild alertness to heightened anxiety and body tension. Regular users who suddenly stop consuming caffeine may experience withdrawal symptoms including drowsiness, headaches, irritability, nausea and vomiting and depression. Although the amounts of caffeine needed to affect each person differ. People who drink caffeine regularly develop a reduced sensitivity and require higher doses of caffeine to achieve the same effects as someone who doesn't consume it regularly. This means that the more caffeine you consume, the more caffeine you need to feel the same effects.
Caffeine moves through the body within a few hours after it is consumed.
It is not stored in the body, but you may feel its effects for up to 6 hours if you're sensitive to it. Caffeine has health risks for certain users. Small children are extremely sensitive to caffeine. Caffeine can aggravate heart problems or nervous disorders, and some teens may not be aware that they are at risk. Although the effects of caffeine vary from one person to the next, health care providers recommend that people should consume no more than about 100 milligrams of caffeine daily.