How long does caffeine remain in the blood stream?

Answer 1

While the exact amount of time that caffeine will remain in the blood stream is different from person to person depending on the different metabolic rate of different people, it can also be different in the same person from day to day depending on the level of hydration, as well as the presence of fats and proteins in the stomach and bloodstream at any particular moment.

Once all caffeine intake is stopped, reduction from the blood stream will begin in 2-3 hours and proceed slowly until all traces are gone within 12-24 hours.

How long caffeine remains available in the blood stream to stimulate the central nerve system is important to anyone who is going through a caffeine headache. This is the kind of headache that begin from prolonged and repeated consumption of caffeine containing substances (chocolate, coffee, tea, cola drinks and drugs) to the point that a deep dull headache occurs behind the eyes (occasionally just one eye) and spreads upward to the top of the head until the entire head hurts.

It is estimated that caffeine withdrawal symptoms (headaches, nervousness, irritability, lack of appetite and muscle cramps) can occur in those sensitive individuals to consume 500 mg of caffeine or more per day for two weeks or more.