Your morning coffee, a can of energy drink before the gym, a matcha latte in the afternoon: caffeine is one of the most widely consumed substances in the world. But what does caffeine do to your body, how long does it last and how much caffeine is too much? In this guide we cover the effects of caffeine on your brain, your sleep and your training, with clear numbers per drink and practical tips so you get the benefits without overdoing it.
A quick bit of history: the word caffeine comes from the German Kaffee and the French café. It was first isolated from coffee beans in 1819, but according to legend an Ethiopian goat herder discovered its effects centuries earlier, when his goats became unusually lively after eating coffee cherries.
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Caffeine in short
What is caffeine?
Caffeine is a natural stimulant found in more than 60 plants, including coffee beans, tea leaves, cacao and guarana. It's also produced synthetically and added to foods and drinks such as soft drinks, energy drinks, sports supplements and some over-the-counter medicines. Chemically, caffeine belongs to a group of compounds called methylxanthines.
Caffeine acts on the central nervous system. According to the European Food Safety Authority (EFSA), a dose of 75 mg or more can help increase alertness and concentration. That's roughly the amount in a single espresso or a cup of matcha.
What does caffeine do to your body?
After you drink or eat something with caffeine, your body absorbs it quickly and almost completely. Most of it reaches your bloodstream within 30 to 120 minutes.
The main effect runs through adenosine, a signalling substance that builds up in your brain while you're awake. The more adenosine, the sleepier you feel. Caffeine has a similar shape and binds to the same receptors, so adenosine can't do its job. The result: you feel more alert and less tired, until the caffeine wears off and the build-up of adenosine takes over again.
Caffeine also stimulates the release of adrenaline, the "fight or flight" hormone. That explains several physical effects:
- Your heart beats faster
- Your blood pressure rises temporarily
- Your muscles get ready to act
- Your airways open
- Your liver releases extra sugar into the blood
- Your pupils dilate
This is also why one cup of coffee too many, or a highly caffeinated energy drink, can make you feel tense, restless or jittery.
How long does caffeine take to kick in and how long does it last?
Most people notice the first effects of caffeine after 15 to 45 minutes. Levels in the blood peak after about 30 to 60 minutes, sometimes up to 2 hours.
The half-life of caffeine
The half-life of caffeine is on average around 5 hours, but it can range from roughly 3 to 7 hours depending on genetics, age, pregnancy, medication and smoking. Half-life means the time it takes for your body to clear half of the caffeine. If you drink an energy drink with 100 mg of caffeine at 16:00, there's still around 50 mg in your system at 21:00.
How long does caffeine stay in your system?
Because it breaks down gradually, it can take 10 hours or more before caffeine has almost completely left your body. That's why caffeine late in the afternoon can still affect your sleep, even if you don't feel it anymore.
How much caffeine is in coffee, tea, cola and energy drinks?
The amount of caffeine varies a lot per drink, per brand and per preparation. This table gives you an overview of average values:
| Drink or product | Serving | Caffeine (approx.) |
|---|---|---|
| ☕ Filter coffee | 1 cup | 95 mg |
| ☕ Espresso | single / double | 63 mg / 125 mg |
| ☕ Instant coffee | 1 cup | 30 to 90 mg |
| ☕ Decaf coffee | 1 cup | about 3 mg |
| 🫖 Black tea | 1 cup | about 45 mg |
| 🍵 Green tea | 1 cup | 20 to 45 mg |
| 🍵 Matcha | 1 tsp (2 g) | 40 to 90 mg |
| 🥤 Cola | 330 ml can | about 32 mg |
| 🥤 Red Bull | 250 ml can | 80 mg |
| 🥤 Monster Energy | 500 ml can | about 160 mg |
| 🥤 Fit Energy | 250 ml can | 100 mg |
| ⚡ Pre-Workout Shot | 60 ml | 200 mg |
| 💪 Perfection Pre-Workout | 1 scoop / 2 scoops | 160 mg / 320 mg |
How much caffeine is in coffee?
A regular cup of freshly brewed coffee contains around 95 mg of caffeine. A single espresso contains about 63 mg, a double around 125 mg. Instant coffee typically contains 30 to 90 mg per cup. Even decaf isn't completely caffeine free: an average cup still contains around 3 mg.
How much caffeine is in tea and matcha?
A cup of black tea has about 45 mg of caffeine, although some varieties contain up to 90 mg. Green tea usually contains 20 to 45 mg. Matcha contains more, because you drink the whole ground leaf: around 40 to 90 mg per teaspoon. Read everything about it in our blog what is matcha. Rooibos (redbush) tea is naturally caffeine free, and herbal teas contain little to none.
How much caffeine is in cola?
A 330 ml can of regular cola contains around 32 mg of caffeine, and the diet version about 42 mg. That's less than a cup of coffee, but if you drink several cans a day it quickly adds up.
How much caffeine is in energy drinks?
Energy drinks vary widely. A 250 ml can of Red Bull contains 80 mg of caffeine, while most 500 ml cans of Monster Energy contain around 160 mg. Our Fit Energy contains 100 mg of naturally sourced caffeine per 250 ml can, is sugar free, has only 10 kcal and contains 70 mg of magnesium, which contributes to normal energy-yielding metabolism. Discover more in our Fit Energy blog or browse all energy drinks.
How much caffeine per day is safe?
EFSA considers the following amounts safe:
- Healthy adults: up to 400 mg of caffeine per day, spread over the day.
- Single dose: up to 200 mg at once (about 3 mg per kg of body weight).
- Pregnancy and breastfeeding: up to 200 mg per day.
- Children and teenagers: up to 3 mg per kg of body weight per day.
So, how much caffeine is too much? For most adults, more than 400 mg a day or more than 200 mg in one go increases the chance of side effects. Remember that everything counts: coffee, tea, cola, energy drinks, but also pre-workouts and fat burners, which often contain caffeine too.
Is 200 mg of caffeine a lot?
200 mg is roughly two cups of filter coffee and the maximum EFSA considers safe for a single dose in healthy adults. It's a common amount in pre-workouts, such as our Pre-Workout Shot and BF10 Pre-Workout. For people who rarely consume caffeine, or who are sensitive to it, it can feel like a lot. Start lower if you're not used to it.
Is caffeine good for training?
Caffeine is one of the most researched ingredients in sports nutrition. The International Society of Sports Nutrition (ISSN) concludes in its position stand that caffeine can improve performance in many types of exercise, including endurance, high-intensity and strength training. Studies usually use doses of 3 to 6 mg per kg of body weight, taken around 60 minutes before training. For someone weighing 70 kg, that's about 210 to 420 mg. Lower doses, from around 2 mg per kg, can also have an effect, and more isn't always better.
Some practical tips:
- Timing: take caffeine about 30 to 60 minutes before your session.
- Start low: new to caffeine or sensitive? Start with 100 mg, for example a can of Fit Energy, or one scoop of Perfection Pre-Workout (160 mg).
- Don't stack: don't combine a pre-workout with coffee and energy drinks in the same hour.
- Tolerance: if you use caffeine every day, you'll notice the effect less. Many people only use a pre-workout on their heaviest training days.
- Training late? Choose a pre-workout without caffeine to protect your sleep.
Want to know more? Read our complete pre-workout guide, or discover the formulas of BF10 Pre-Workout and Perfection Pre-Workout. Caffeine is also often combined with other performance ingredients such as creatine, beta-alanine and citrulline. Remember that supplements are never a substitute for a varied, balanced diet.
Caffeine and sleep
Because caffeine blocks adenosine, it can make it harder to fall asleep and reduce the quality of your sleep, especially deep sleep. Research shows that even 400 mg of caffeine taken 6 hours before bedtime can noticeably disrupt sleep. A practical rule: stop caffeine at least 6 hours before you go to bed, or earlier if you're sensitive.
Poor sleep can turn into a vicious circle: you sleep badly, feel tired, reach for more coffee and then sleep badly again. Find more tips in our guide to sleeping well and in our blog about your routine before bedtime.
Too much caffeine: side effects and symptoms
Is caffeine bad for you? In moderate amounts, caffeine is safe for most healthy adults. Too much caffeine, or caffeine when you're sensitive to it, can cause:
- Restlessness, nervousness or anxiety
- A racing heart or palpitations
- Trembling hands
- Headache or dizziness
- Stomach complaints
- Trouble falling asleep
A caffeine overdose from normal drinks is rare, but very high doses, for example from caffeine powders or combining several products, can be dangerous. Experiencing chest pain, severe palpitations or confusion after consuming caffeine? Seek medical help straight away.
Can caffeine make you tired?
Yes, indirectly. When the caffeine wears off, the adenosine that has built up hits you all at once, which can feel like a dip. Caffeine late in the day can also disrupt your sleep, making you more tired the next day.
Is caffeine addictive?
If you consume caffeine every day, your body gets used to it. Your brain adapts by making extra adenosine receptors, so you need more caffeine for the same effect. In psychiatry's diagnostic manual (DSM-5), caffeine withdrawal is recognised as a condition, and "caffeine use disorder" is listed as a topic that needs more research.
Symptoms of caffeine withdrawal
If you suddenly stop, withdrawal symptoms can appear after 12 to 24 hours and usually last a few days:
- Headache
- Fatigue and low energy
- Difficulty concentrating
- Irritability
- Low mood
You can reduce these symptoms by cutting back gradually rather than quitting cold turkey, drinking enough water and getting enough sleep.
Is caffeine a drug?
Technically, caffeine is a psychoactive substance because it affects your brain. Its effects are much milder than those of other stimulants, and it's legal and widely available almost everywhere in the world. That's exactly why it's worth keeping track of how much you consume.
Caffeine-free alternatives and lower-caffeine options
Want to cut down on caffeine? Try these options:
- Decaf coffee and rooibos or herbal tea for your usual hot drink.
- A lower-caffeine drink, like green tea or matcha, instead of a strong coffee or energy drink.
- Pre-workouts without caffeine for evening training.
- The basics: enough sleep, water, daylight, exercise and nutrient-rich food. Get inspired by our superfoods list.
FAQ: caffeine
How long does caffeine stay in your system?
The half-life of caffeine is on average around 5 hours (roughly 3 to 7 hours). After 5 hours about half is still in your body, and it can take 10 hours or more before it's almost completely gone.
How much caffeine is too much in one day?
For healthy adults, EFSA considers up to 400 mg per day safe, with a maximum of 200 mg at once. During pregnancy the limit is 200 mg per day.
Is 200 mg of caffeine a lot?
It's about two cups of coffee and the maximum single dose EFSA considers safe for healthy adults. It's fine for most people who are used to caffeine, but can feel strong if you rarely consume it.
When should I stop drinking caffeine before bed?
Stop at least 6 hours before bedtime. If you're sensitive to caffeine or sleep badly, stop earlier, for example after lunch.
Does caffeine improve workout performance?
Research summarised by the ISSN shows that caffeine can improve performance in many types of exercise at doses of about 3 to 6 mg per kg of body weight, taken 30 to 60 minutes before training. Individual responses vary.
How long does caffeine take to kick in?
Most people feel the effect after 15 to 45 minutes. Levels in the blood peak after about 30 to 60 minutes.
Does matcha have less caffeine than coffee?
Usually yes. A teaspoon of matcha contains around 40 to 90 mg of caffeine, compared to about 95 mg in a cup of filter coffee. Read more in our matcha guide.
Sources
- European Food Safety Authority (EFSA) - Caffeine
- Guest N.S. et al. (2021). International Society of Sports Nutrition position stand: caffeine and exercise performance
- Drake C. et al. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine.
- Meredith S.E. et al. (2013). Caffeine Use Disorder: A Comprehensive Review and Research Agenda. Journal of Caffeine Research.
- American Academy of Sleep Medicine - Sleep Education: Caffeine and sleep
Any questions about caffeine, energy drinks or our caffeinated products? Get in touch with our Nutrition Experts via Instagram or our customer service.
