Between 3 to 12 hours
As long as caffeine is in your blood, it's effects will also manifest. The time it takes for the body to eliminate one half of a caffeine dose is normally between 3 to 12 hours. It is called the half-life of caffeine. It also varies from man to woman. Scientifically, caffeine resides longer in women’s system than that of men. The average half-life of caffeine in healthy humans persists for 4.9 hours. In men, typically residing between 5 to 9 hours, after the consumption of caffeine. Onset and Duration. It takes approximately 15 to 45 minutes for caffeine to reach its peak levels in your bloodstream. Caffeine has a half-life of approximately five to six hours, meaning that it takes this long for its concentration in your bloodstream to reduce by half. The time it takes for the body to eliminate one half of a caffeine dose is normally between 3 to 12 hours. It is called the half-life of caffeine. Several factors can shorten … or lengthen the half life of caffeine. Smoking, medications and diseases are some factors. How Long Does Caffeine Stay in the Body? In most cases, caffeine has a half-life of about 5 hours (meaning 5 hours is needed to eliminate half the coffee amount). However, it might take longer – for instance, a pregnant woman might have caffeine in her system up to 20 hours after she ingests it. The half-life, which is the time required by the body to metabolize or inactivate 1/2 of a substance activity, for caffeine (doses lower than 4.50mg/lb) ranges from 2.5 to 10hrs.
http://neutral-izer.blogspot.com/2007/09/how-long-does-caffeine-stay-in-your.html http://www.actabit.com/long-coffee-caffeine-stay-system/ http://www.livestrong.com/article/272782-how-long-does-coffee-caffeine-stay-in-your-system/ http://www.answers.com/Q/How_long_does_caffeine_from_soda_stay_in_your_system http://www.med-health.net/How-Long-Does-Caffeine-Last.html http://www.dotfit.com/content-35789.html
how long does caffeine stay in your system for