Caffeine is known to have a half-life of 5 hours in adults, whereas in neonates, the half-life of caffeine averages 80 hours; a stark contrast. Among elderly individuals (age 65+), ability to metabolize caffeine decreases by 33% compared to adults; from a rate of 1.5 ml/min to 1.0 ml/min.
http://mentalhealthdaily.com/2015/10/21/how-long-does-caffeine-stay-in-your-system/
Report Abuse. 1  It depends; those who drink lots of coffee become 'caffeine-tolerant'. If they were to have a coffee late in the evening it wouldn't make much difference. 2  it can take 15-20 minutes.. the effects can last a few hours.. 3  is a stimulant and it will elevate heart rate, increase blood flow, and raise body temperature.
https://uk.answers.yahoo.com/question/index?qid=20100217075459AAovOqy
These discontinuation effects may persist long after caffeine has been fully cleared from your system. Most sources suggest that the average plasma half-life of caffeine in healthy adults is within the range of 3 to 5 hours. Though 50% of the drug may be cleared from your body within 5 hours, it will take ~1.15 days to fully eliminate caffeine from your system.
http://mentalhealthdaily.com/2015/10/21/how-long-does-caffeine-stay-in-your-system/
In healthy adults, the half-life of caffeine is 4.9 hours. In pregnant women, the half- life is 9-11 hours. In infants as well as young kids, the half-life of caffeine is longer than the adults, about 30 hours. Patients with severe liver disease, caffeine may accumulate in the liver with the half-life up to about 96 hours.
http://www.just-health.net/How-Long-Does-Caffeine-Last.html
Caffeine begins to affect your body very quickly. It reaches a peak level in your blood within 30 to 60 minutes. It has a half-life of 3 to 5 hours. The half-life is the time it takes for your body to eliminate half of the drug. The remaining caffeine can stay in your body for a long time. Coffee accounts for 54% of the caffeine consumption in the world.
http://sleepeducation.org/news/2013/08/01/sleep-and-caffeine
It is the world's most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. There are several known mechanisms of action to explain the effects of caffeine.
https://en.wikipedia.org/wiki/Health_effects_of_caffeine
Typically, the peak of concentration is 15 to 120 minutes after caffeine is consumed. Caffeine stays in the bodies of men for five to nine hours, but the amount of time is reduced by 30 to 50 percent in smokers.
https://www.drugs.com/answers/long-caffeine-stay-body-613856.html
Toxic doses, over 10 grams per day for an adult, are much higher than typical doses of under 500 milligrams per day. A cup of coffee contains 80–175 mg of caffeine, depending on what bean (seed) is used and how it is prepared (e.g. drip, percolation, or espresso). Thus it requires roughly 50–100 ordinary cups of coffee to reach a lethal dose.
https://en.wikipedia.org/wiki/Health_effects_of_caffeine
How Long does Caffeine Last in the Body? Caffeine is a substance found in coffee, tea or chocolate and also some medicine components which stimulates the central nervous system, giving the effects as following: Awake. Caffeine in coffee can stimulate the central nervous system in the brain, giving you a clear thinking and refresh your brain.
http://www.just-health.net/How-Long-Does-Caffeine-Last.html
The length of stay for caffeine in women using oral contraceptives is approximately 12 to 15 hours, and can be as long as 15 hours in pregnant women as well, according to the Coffee Science Information Centre and the International Coffee Organization. Take care, maso.-.
https://www.drugs.com/answers/long-caffeine-stay-body-613856.html
caffeine takes how long effect
The effect of caffeine takes a few hours. The effects of caffeine last a few hours.