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How long does caffeine last in your system?

Caffeine – is it good or bad for you?

Caffeine makes the world go ‘round. But how long do the effects of caffeine from a cup of coffee, tea or even an energy drink last in the body? The answer to this question will vary from person to person, but for the average healthy adult, the effects of caffeine will last around six hours. 

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Caffeine tolerance also seems to vary between individuals – some people feel energised after one cup, while others chug cups of coffee all day. So exactly how long should caffeine last in your body, and is coffee full of health benefits or is it really just bad for you? 

What is caffeine? And how does caffeine work?

Caffeine is the primary active compound in coffee. It’s a mild central nervous system stimulant, meaning it increases brain activity and keeps you awake and focused. It does this by blocking adenosine receptors in the brain. The caffeine molecule (which looks like a lot like adenosine) latches onto these receptors so that adenosine can’t tell your brain to be drowsy.

Caffeine isn’t just found in coffee – caffeine also occurs naturally in cocoa beans and tea leaves and it’s often added to colas and energy drinks. There are also some prescription drugs with added caffeine.

A woman drinking coffee while working on the computer
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How long does it take for caffeine to work?

According to Caffeine Informer, it takes around 15 to 20 minutes for caffeine and the effects of it to be felt by the body. But you do start absorbing caffeine as soon as you start drinking coffee, since caffeine can very easily pass through epithelial tissue such as the lining of your mouth, throat and stomach.

How long does caffeine last in the body?

A study by the National Center for Biotechnology Information has shown that on average, the half-life of caffeine in a healthy person is 5.7 hours. This means caffeine can stay in your system for that long before it is metabolised and its effects fully wear off.

In the same study, it’s mentioned that people who have liver problems have a much longer half-life for caffeine – a 35-year-old man with liver disease had a 60-hour half-life, while a 49-year-old woman with the same issues had a 168-hour half-life!

Espresso coffee machine with two coffee cups
(Credit: Getty) (Credit: Getty)
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A gene called CYP1A2 is needed by the liver to break down 95% of the caffeine in the body. Some people may have a defective gene, or they may not have it altogether. Healthline lists this as one of the causes of caffeine sensitivity, which manifests as headaches, anxiousness, and insomnia.

Is coffee bad for you?

Coffee is a mild diuretic and a stimulant, so it’s often believed to be both dehydrating and bad for your heart. However, turns out that there’s no significant risk of dehydration, and studies have shown that it’s safe to drink up to six cups of coffee without raising your risk for heart disease!

What are some alternatives to caffeine?

While caffeine does have plenty of benefits, there are some people who have to steer clear of it altogether. Here are some caffeine alternatives that might give you a similar energy boost:

Vitamins: If you find yourself generally lacking in energy, it might be due to a vitamin deficiency. Vitamin B12 in particular is one that you may find yourself low on, especially if you’re vegan or vegetarian. This is because our body doesn’t make it, and we usually get it from animal-based foods. Consult your doctor before taking vitamin supplements.

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Exercise: While it sounds counterproductive to exercise when you’re already feeling low on energy; exercise can elevate your endorphin production, improve your heart health, and improve sleep – giving you a natural energy boost.

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