Coffee and caffeine is a stimulant that your body rapidly absorbs. How long coffee stays in your system depends on your metabolism and lifestyle. Let’s start by understanding how caffeine gets into your system, how it’s metabolized, and finally removed from the body.
How your body absorbs caffeine
Caffeine absorption starts right with the first sip. As soon as you drink, it passes through the lining of the mouth and into your stomach and intestines. This is why you’ll feel the first rush of caffeine almost immediately or within 10-15 minutes of drinking coffee. In about 45 minutes, 99% of the caffeine from your coffee is absorbed into the bloodstream. This is the peak concentration. During this time, you’ll feel the maximum effects of the coffee.
Once it is in your blood, the caffeine travels across the body and to the brain. Here, it binds to specific receptors to keep you alert. Of course, like any other substance, the liver breaks down caffeine. This process is called metabolism and the rate of metabolism determines how long the caffeine stays in your system. The average half-life of caffeine (how long it takes for half the amount of caffeine to be metabolized) is 4 to 6 hours. So, once you drink a cup, coffee stays in your system for about 5 hours, give or take.
Everyone is different though
However, keep in mind that this duration is an average number and it can vary from person to person. How long coffee stays in your system is controlled by your metabolism. This, in turn, is controlled by your genetics, lifestyle, medications, age, and existing medical conditions.
People who drink coffee regularly may metabolise it faster and be less affected by caffeine over time. Some people are very sensitive to caffeine, and coffee may stay in their system longer, while some may metabolise it very quickly and experience a caffeine ‘crash’.
After metabolism, a small amount of caffeine is still in your system and this gets filtered out by the kidneys and removed from the body.