How Long Does Coffee Stay in Your System? ( Science-Backed Answer ! )

9 min read JAN 17, 2023

The time taken for coffee to leave your system depends on your body's metabolism rate or your brain's neurological health. The rate at which your body metabolizes coffee varies based on genetics, age, exercise, sex, and more.

To have a clear picture of how long coffee stays in your system, you must first understand what caffeine is, how it works, and its effects on your body. 

What is Caffeine, and how does it Work?

Caffeine, also known as caffein, is a bitter alkaloid found in coffee, tea, and other drinks such as sodas and energy drinks that stimulates the central nervous system. The amount of caffeine in coffee or tea depends on the type of coffee, such as black brewed coffee or tea, such as green tea or black tea.

Caffeine is the compound responsible for the energy boost, great mood, and alertness you gain when you consume coffee. That is why several people love kick-starting their day with a cup of coffee.

Once you consume coffee, caffeine is directly absorbed into the bloodstream from the gastrointestinal tract. The gastrointestinal tract or gut is the digestive system's passageway that runs from the mouth to the anus. Some of the caffeine reaches the liver, which is broken down into different compounds that impact the functions of the human body.

The brain is the most impacted organ by the caffeine within your bloodstream. Adenosine is a hormone produced by your brain that triggers sleep. You will feel sleepy when adenosine molecules attach to their receptors and activate them. Caffeine keeps you alert and awake by blocking adenosine molecules from attaching to their receptors.

Caffeine also improves your mood and focus by stimulating the production of dopamine. Dopamine is a hormone produced by the brain that makes you feel happy and relaxed when produced.

The Effects of Caffeine on Your Body

Evidence indicates that the effects of caffeine on dopamine and adenosine receptors may have long-term advantages, such as decreasing the risks of infections such as Alzheimer's, Parkinson's, and some cancer types like liver cancer. Caffeine can also aid with weight loss.

Despite all the benefits, drinking too much caffeine can lead to addiction. Caffeine can potentially cause anxiety, increased blood pressure, and daytime sleepiness.

Sleep is a critical aspect of your life, and long-term poor sleep habits caused by taking too much caffeine can deteriorate your health.

To have a better sleep schedule and still enjoy your morning cup of coffee, you must understand how caffeine affects your sleep, the factors determining how long caffeine will clear from your system, and your coffee sensitivity category.

How Caffeine Affects Your Sleep

If you consume coffee at the wrong time, your sleep latency and the time you spend in deep sleep are affected. Sleep latency refers to the time it takes for you to fall asleep.

Taking caffeine a few minutes before bedtime harms your circadian rhythm. The circadian rhythm is the 24-hour body schedule that oversees your sleep cycles.
Additionally, drinking coffee a few minutes before going to sleep minimizes your slow-wave deep sleep time, making you feel tired and poorly rested in the morning. 

5 Factors that Determine How Long Caffeine Takes to Clear from Your System

The time taken for caffeine to leave your system is determined by the amount you consume relative to the half-life of caffeine. The half-life of caffeine is four to six hours, averaging at five hours.

For example, if you consume 100 milligrams (mg) of caffeine in 5 hrs, there would be 50 mg of caffeine in your system.

Although the half-life of caffeine is scientifically proven, it varies from person to person due to various factors, including metabolism and brain neurological health. Due to these factors, it ranges from about one and a half hours to nine hours.


Caffeine metabolism is the rate at which caffeine is broken down within the system. The caffeine metabolism in your body occurs due to the production of an enzyme called Cytochrome P450 1A2 or CYP1A2. Two genes are responsible for the production of this enzyme.

The CYP1A2*1A gene produces an enzyme that metabolizes caffeine rapidly. In contrast, the CYP1A2*1F gene produces an enzyme that metabolizes caffeine at a slower rate. Everyone has two copies of these genes.

For example, you can either have a CYP1A2*1A plus a CYP1A2*1F combination or a combination of the same gene variations. If you have two CYP1A2*1A genes, your metabolism will be faster, and if you have two CYP1A2*1F genes, your metabolism will be much slower.

Other than having either of the genes, other factors affecting caffeine metabolism include: 


If you are young, your metabolism rate is fast; otherwise, if you are old, your metabolism is slow. 

Working Out

Caffeine leaves your system faster if you work out because exercising increases your metabolism. The effects of caffeine peak after about 30 minutes to 60minutes.

That is why it is recommended that you take coffee for at least 30 minutes before working out to boost your energy and enhance your endurance.


Smoking speeds up your metabolism.


Some medications have been proven to increase or decrease your metabolism. For example, birth control pills have been found to increase women's metabolism.

Brain Neurological Health

Caffeine impacts the neurological receptors of your brain. Therefore, if you might have any neurological condition, your reaction to caffeine and the time it takes for it to leave your system will vary.

Other than observing these factors when determining how long caffeine effects might last, do the following to decrease the time that caffeine lasts in your system:

  • Go for a jog or work out to increase your body's caffeine metabolism.
  • Increase your water intake.
  • Incorporate cruciferous vegetables or broccoli into your meals as they hasten metabolization. 

Caffeine Sensitivity- Types and Symptoms

Caffeine sensitivity describes your reaction to caffeine and the degree to which you experience the effects of caffeine. The effects vary from one person to the other based on different factors.

You should observe and keep a log of how you feel after taking coffee, how long you feel the effects, and how long they last. Analyze the logged results to determine your coffee sensitivity group.

You can seek the services of a professional doctor to determine your metabolization genes. People who metabolize caffeine fast are less sensitive to caffeine, while those who metabolize caffeine slower are highly sensitive.

Knowing your sensitivity allows you to understand how long caffeine's effects might take to wear off. These are the three well-known classes of coffee sensitivity: 

Normal Sensitivity

Many people fall into this category. People with normal sensitivity can consume up to 400mgs of caffeine in a day without feeling the nasty effects of caffeine.


This is a class of people who can take too much caffeine within the day and not experience the adverse effects of caffeine. Based on a study undertaken in 2011, about 10% of people possess a gene that allows them to consume too much caffeine comfortably.


People hypersensitive to caffeine experience adverse effects when they consume a small amount. Their genetic composition or liver metabolization capability makes them incapable of withstanding the effects of caffeine. 

Some of these effects and symptoms include:

  •   Jitters
  •   Restlessness
  •   Insomnia
  •   Headache
  •   Anxiety
  •   Nervousness
  •  Racing heart 

Do not confuse hypersensitivity with caffeine allergy. Caffeine allergy only occurs when your immune system releases antibodies to counter caffeine.

Caffeine allergy has the following symptoms: 

  • Hives
  • Tongue or throat swelling
  • Itchy skin
  • Severe cases might experience anaphylaxis, or difficulty breathing

Once you have determined your sensitivity levels, you can plan your daily caffeine dosage. 

Recommended Caffeine Dosages 

If your sensitivity is normal, you can consume around 200 to 400 mg of caffeine without experiencing any ill effects. Avoid consuming more than 600 mgs of caffeine a day.

Currently, there are no recommended measures for adolescents and children. Pregnant women should limit their caffeine intake to 200mgs and avoid consuming caffeine before breastfeeding. The caffeine in breast milk might affect the child's mood.

If your sensitivity is high, you can stop drinking caffeine or reduce your intake to around 30 to 50mgs daily. Alternatively, you can replace your coffee with green tea and have a 5-ounce cup with 30mgs of caffeine. Decaffeinated coffee is a great option too as it has only 2 milligrams of caffeine.

Use our low-acidic coffee if you have gastro-oesophageal reflux disease (GERD). Low-acid coffee guarantees a healthy recovery process and allows you to enjoy your coffee worry-free.

Suppose you had not come across this article earlier enough to learn how to consume coffee in a healthier way and ended up developing coffee tolerance; there is a solution to that.

Caffeine tolerance occurs due to regular caffeine consumption over a long period. Eventually, you start consuming more to trigger your desired positive effects.

Caffeine tolerance pushes you to take more caffeine daily, which may lead to addiction. Other health issues may follow, including mood swings, depression, impaired judgment, irregular heartbeat, emotional fatigue, and anxiety. Caffeine Cycling is the solution to caffeine tolerance. 

What is Caffeine Cycling?

Caffeine tolerance and addiction arise due to your body system adapting to the caffeine amount you drink daily. Caffeine cycling involves altering the amount of caffeine you take each day.

For example, if you take 300mg of caffeine daily, start by reducing it to 200mg, then 100mg, then 50mg, and eventually boost it back to 300mg. This makes it hard for your body to create a caffeine intake pattern. Moderate consumption ensures that you do not become caffeine tolerant.

When you start practicing caffeine cycling, you might experience caffeine withdrawal symptoms such as feeling foggy, drowsiness, fatigue, and decreased alertness. Though, it would be best if you did not stop because caffeine withdrawal indicates that your body system is adapting to caffeine cycling.

Caffeine cycling is the most effective way to avoid taking too much caffeine if you are a daily coffee drinker. Use this article to determine and create a healthy coffee intake schedule that does not affect your daily mood or sleep. You can also engage wellness professionals to guide you through the process. 

Frequently Asked Questions (FAQs)

How long does caffeine take to kick in?

If you consume caffeine, you would have to wait for about 30 mins for caffeine to kick in.

How long does 100mg of caffeine last?

100mg of caffeine will last 10 hours or more in your system.

Will 50mg of caffeine keep me awake?

Yes. 50mg of caffeine can keep you awake for about 2 hours straight.

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Medical Disclaimer
This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Charles Livingston nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program.

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