How Long Caffeine Stays in Your System
- The half-life of caffeine is 3-6 hours and it can take 10 hours to leave your system completely.
- Consuming caffeine 6 hours before bed can disrupt sleep so it’s best to avoid it in the afternoon.
- You can’t get rid of caffeine faster but you can mitigate symptoms by hydrating and exercising.
- Visit Insider’s Health Reference library for more advice.
Caffeine is one of the most commonly used drugs in the world. It can help you feel more alert and awake in about 15 minutes after consumption.
But as powerful as caffeine can be to help that morning slump, it can be equally detrimental for your sleep if you consume it too late in the day. That’s because of the way caffeine blocks the adenosine receptors in your brain that signals the body to feel sleepy.
Here’s how long caffeine can stay in the body and how it affects you if you consume too much.
How long does caffeine last?
The half-life of caffeine — which refers to the time it takes the body to get rid of half the amount you consumed — is about three to six hours.
So, if you drank an 8 oz cup of coffee (about 96 mg of caffeine) with breakfast, you’d have about 48 mg of caffeine left in your system around lunchtime. And as long as there’s at least some caffeine in your system, you may experience its effects.
It can take approximately 10 hours for caffeine to leave your system completely, says Deborah Cohen, DCN, RDN, associate professor in the Department of Clinical and Preventive Nutrition Sciences at Rutgers University.
So, if you drank one cup of coffee at 8 a.m., the caffeine may remain in your bloodstream until 6 p.m.
A small 2013 study found that consuming caffeine six hours before bedtime can still disrupt sleep. To ensure a good night’s sleep, it might be best to avoid caffeine completely in the afternoon.
However, it’s important to remember that everyone metabolizes caffeine differently, so how long it takes you to stop feeling the effects of caffeine may not be the same as someone else.
“While there are some generalities with caffeine, because all of our bodies are unique in some ways, caffeine can impact us all at different intensities. Age, weight, frequency of consumption, and even genetic factors all play a role in how one metabolizes caffeine,” says Ilisa Nussbaum, MPH, RDN, clinical dietitian nutritionist at the Yale New Haven Hospital.
Caffeine during pregnancy and breastfeeding
According to The American College of Obstetricians and Gynecologists (ACOG), both pregnant and breastfeeding people can consume up to 200 mg of caffeine per day.
But it’s important to note that pregnant people metabolize caffeine slower than the average adult. In fact, the half-life for caffeine is about 11.5 to 18 hours by the end of pregnancy.
Breastfeeding people should also refrain from drinking more than the recommended amount because the drug can be passed along to the baby through breast milk. If you consume too much caffeine, the baby may end up sleeping poorly and feeling irritable or fussy.
“It’s best to be particularly cautious with the amounts of caffeine you consume if you have an infant that is small for his or her gestational age or one who was born prematurely. Caffeine also takes longer to metabolize in preterm and younger or smaller infants,” says Amanda E. Wright, MD, internal medicine physician and Virtual Care Team Lead at Eden Health.
How much is too much?
Some people are immune to the effects of caffeine, but if you’re like most people and you consume more than the recommended limit of 400 mg of caffeine/day, you may experience the following symptoms:
- Increased blood pressure
- Dizziness
- Dehydration
- Insomnia or restless sleep
- Feeling jittery, shaky, or nervous
- Headaches
- Racing or abnormal heartbeat
- Digestive issues like diarrhea or reflux
- Anxiety
“There can also be rebound fatigue once the effects of the caffeine wear off. As there are wide ranges of reactions to caffeine, it’s important to pay attention to how your body feels after ingesting caffeine and adjust as needed,” says Nussbaum.
Here’s a table of the caffeine content in common beverages to help you avoid exceeding the consumption limit:
“The [amount of caffeine] per serving varies widely across brands and sizes so it is best to check the labels. Starbucks servings have notoriously high amounts of caffeine. A tall usually has between 200 to 280 mg caffeine and it goes up from there,” says Wright.
Can you get caffeine to wear off faster?
If you’re experiencing symptoms from having too much caffeine, you might want it to wear off faster. However, once you’ve ingested too much caffeine, you can’t speed up the metabolic process, experts say. So you just have to wait out.
That said, here are some things you can do to manage the symptoms of caffeine overconsumption:
- Stop consuming food and drinks with caffeine: If you’re already experiencing symptoms, don’t consume more caffeine. Avoid all food and drinks containing the drug, like chocolate or tea.
- Drink more water: Dehydration can worsen caffeine-induced jitters or headaches, so make sure to increase your water intake, says Wright.
- Do some exercise: Caffeine can make you feel restless, and exercising is a great way to use more energy and reduce anxiety.
- Practice deep breathing techniques: Deep breathing is a great way to stimulate the vagus nerve and slow down your heart rate, which helps with anxiety, says Wright.
Insider’s takeaway
It takes 15 minutes for the effects of caffeine to kick in, but it can remain in the bloodstream for about 10 hours. If you consume too much caffeine, you may experience symptoms like anxiety, headaches, jitters, or dehydration.
There’s nothing you can do to make caffeine wear off faster, but you can drink more water, exercise, and practice deep breathing techniques to deal with the symptoms of overconsumption.
“I know it’s boring to hear this, but moderation is key. Stick with no more than the recommended intake and adjust depending on your body’s reaction,” says Nussbaum.
