How long caffeine stays in your system depends on genetic factors and how much caffeine you've consumed. Generally speaking, it can take up to 10 hours for all traces of caffeine to leave your bloodstream.
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The half-life of caffeine is typically five to six hours, though how long caffeine lasts in your body varies depending on genetic factors. Caffeine can stay in your system for up to 10 hours at a time.
Amounts of Caffeine in Coffee
The caffeine content of coffee, tea and soda varies. According to the Mayo Clinic, an 8-ounce cup of brewed coffee can contain 95 to 165 milligrams of caffeine, a 1-ounce shot of espresso can contain 47 to 64 milligrams of caffeine and the caffeine content of an 8-ounce latte or mocha ranges from 63 to 126 milligrams.
The Food and Drug Administration recommends you consume not more than 400 milligrams of caffeine per day, which might not seem like a lot depending on how long caffeine lasts in your body. And, while the caffeine content of packaged drinks may be noted on the drink's label, it's hard to accurately identify the amount of caffeine in homemade or restaurant-made coffees.
Decaf coffee contains significantly less caffeine than a normal brew. According to the Cleveland Clinic, any coffee labeled as decaf has to be at least 97.5 percent caffeine-free. That means an 8-ounce serving of decaf contains 2 to 4 milligrams of caffeine.
How long caffeine lasts may also depend on the type of coffee bean used. An August 2016 study published in the journal European Food Research and Technology found that coffee brewed from the Coffea canephora plant contains twice as much caffeine as coffee brewed from the Coffea arabica plant.
How Long Does Caffeine Last?
According to the Cleveland Clinic, you can feel the effects of caffeine within 15 minutes of consuming your coffee, tea or soda. The level of caffeine in your blood will then increase, peaking one hour later and remaining at this level for a few hours. The clinic says that half of the caffeine you consumed will remain in your body after six hours and that it can take up to 10 hours for your body to get rid of all caffeine from your bloodstream.
However, not everyone responds to caffeine in the same way. For a study published in a December 2016 issue of Human Molecular Genetics, researchers analyzed caffeine metabolites in 9,876 people. They concluded that there are genetic components to how people metabolize caffeine and how often they seek caffeine in the first place.
This research seems to confirm that genetics largely determine how long caffeine stays in your system, which is why people react very differently to caffeine. Drinking coffee after dinner may be no problem for some people, while it will have others struggling to sleep that night.
Read more: How Many Cups of Coffee a Day Can You Drink?
Signs of Overconsuming Caffeine
If you have consumed too much caffeine, you may experience physical symptoms. How long caffeine lasts in your body will influence the length of time you experience these symptoms. Signs of overconsuming caffeine include:
- Feeling shaky or experiencing "the jitters"
- Increased or abnormal heartbeat
- Increased blood pressure
Read more: Natural Alternatives to Caffeine
Decreasing Your Caffeine Levels
Is there anything you can do to cut down on how long coffee lasts? Unfortunately, once you've had a caffeinated drink, you just need to wait it out. That said, there are a number of ways to decrease the amount of caffeine you drink each day.
The University of Michigan Health Service explains that, if you are used to consuming high amounts of caffeine each day, you may experience withdrawal symptoms if you quit caffeine all at once. Potential caffeine withdrawal symptoms include headaches, nausea, anxiety and irritability.
Instead of quitting caffeine cold turkey, the site recommends gradually reducing your intake over a few days or weeks. Options include:
- Watering down your caffeinated drinks. For example, pour out one eighth of your coffee and add hot water instead. Over time, increase the amount you are pouring out and replacing with coffee.
- Switching to decaffeinated coffee. Some people who enjoy the ritual of making and drinking coffee multiple times a day may benefit from switching to decaf, starting with one decaf drink per day and gradually switching over to all decaf. You can still take breaks to make and enjoy your coffee, without consuming so much caffeine.
- Grab a glass of water every time you feel the urge to drink coffee. This can help you break your coffee habit while keeping you well hydrated, too.
Read more: Is Decaf Coffee Bad for Your Health?
Alternatives to Coffee
Depending on how long caffeine stays in your system, you may want to find other ways to boost your energy during the afternoon and evening to avoid interfering with your sleep at night. A few caffeine-free ways to perk yourself up include:
- Taking a short walk. Getting some sunshine and fresh air can boost your energy. If you can't get outside, even just a lap around your office building can stop you from falling asleep at your desk. Plus, regular brisk walks can help you stay active and potentially contribute to weight-loss efforts.
- Sipping a glass of cold water. Drinking a glass of iced water will wake you up pretty quickly, and you don't have to worry about the fallout from caffeine. Unlike coffee, water is not a diuretic, and keeping up your water intake will help with hydration.
- Squeezing in a power nap. Napping during the day isn't possible for everyone, but a short siesta can do wonders for your energy if you can make it work. After a 10 to 20 minute snooze you'll wake up refreshed rather than groggy, ready to tackle the rest of your day. Just don't nap too late in the day, as this might affect how sleepy you feel at night.
- Mayo Clinic: "Caffeine Content for Coffee, Tea, Soda and More"
- Food and Drug Administration: "Spilling the Beans: How Much Caffeine Is Too Much?"
- Cleveland Clinic: "Caffeine: Tips for Breaking the Habit"
- Human Molecular Genetics: "Genome-Wide Association Study of Caffeine Metabolites Provides New Insights to Caffeine Metabolism and Dietary Caffeine-Consumption Behavior"
- University of Michigan Health Service: "Caffeine"
- European Food Research and Technology: "Chlorogenic Acids, Caffeine Content and Antioxidant Properties of Green Coffee Extracts: Influence of Green Coffee Bean Preparation"
- Cleveland Clinic: "Do You Know What’s in Your Coffee?"