From the FDA Drug Label
In neonates, the T1/2 is approximately 3-4 days and the Ae is approximately 86% (within 6 days). By 9 months of age, the metabolism of caffeine approximates that seen in adults (T1/2 = 5 hours and Ae = 1%). The half-life of caffeine is approximately 3-4 days in neonates and 5 hours in adults 1.
- In neonates, the half-life is longer due to immature hepatic and/or renal function.
- The half-life decreases as the infant grows older, approaching adult values by 9 months of age.
From the Research
The half-life of caffeine in healthy adults is approximately 6 hours, as supported by the most recent study 2. This means that after this time period, about half of the caffeine consumed remains in your system. However, this duration can vary significantly between individuals based on several factors.
- Smokers tend to eliminate caffeine more quickly due to enzyme induction,
- while pregnant women process it more slowly. Other factors affecting caffeine metabolism include liver function, medications, age, and genetic variations in the CYP1A2 enzyme responsible for caffeine breakdown. As noted in 3, the half-life of caffeine ranges from 1.5 to 9.5 hours, but more recent research 2 suggests that 6 hours is a more accurate average half-life. It's worth noting that it takes about 4-5 half-lives to eliminate most of a substance from your body, meaning caffeine can affect you for up to 24-30 hours after consumption. The study 2 also highlights the importance of considering caffeine's effects on cardiovascular functioning, particularly in research settings. Overall, individual factors play a significant role in determining the half-life of caffeine, and a 6-hour half-life is a reasonable estimate for healthy adults, as indicated by the latest research 2.