So THAT'S What Happens If You Drink Too Much Coffee

That next caffeine hit is calling your name.
Are you sure you really want that giant cup of coffee?
franckreporter via Getty Images
Are you sure you really want that giant cup of coffee?

Love it or hate it, coffee is an integral part of most people’s lives and supposedly the world’s most commonly used stimulant.

So what happens if you have too much of it?

We all know that the caffeine in coffee wakes you up – that’s partly why we love it – but we do have to be careful with the amount we consume.

How much coffee is too much coffee?

This all depends on each individual, their genes and their tolerance to it – and how strong each drink is.

For context, this is usually how much caffeine is usually in each of these everyday items according to the NHS and US medical outlet, Healthline:

  • Instant coffee has 100mg per 250ml
  • Energy drinks have 80mg per 250ml
  • Black tea has 75mg per 250ml
  • Green tea has 35mg per 250ml

This explains why coffee has such a reputation for being the best way to wake up in the morning, but you could overdo it on the caffeine front through any of the above beverages.

What are the side effects of too much coffee?

Again, it’s not clear how much caffeine might trigger side effects in each person as everyone will have difference tolerances.

But, side effects – which are temporary – are much more likely if you have 1,000mg or more per day in most people. The US Food and Drug Administration recommends you have under 400mg per day.


Anxiety is a well-known side effect. Caffeine basically blocks the effects of adenosine, a brain chemical which makes you tired, according to US website Healthline.

This then activates the central nervous system and released fight or flight hormones.


Coffee is known for fighting off your sleepiness, but what if it goes too far the other way?

The later you have it in the day the more likely it is that your sleep quality will be negatively impacted.

Healthline suggested that caffeine stays in your system for around five hours, although it could linger on for up to nine hours.

Coffee is supposedly the most commonly-used stimulant in the world – and are we surprised?
Anastasiya Mihailovna via Getty Images
Coffee is supposedly the most commonly-used stimulant in the world – and are we surprised?

Gut issues

Yes, too much coffee might give you the shits, as Healthline explains.

Coffee is hailed for being a laxative because it helps the release of gastrin, which speeds up activity in the colon, while caffeine stimulates the bowels by increasing peristalsis.


The website also explains that it is possible to develop a psychology or physical dependency on coffee especially at high doses. People can also suffer from withdrawal if they come off it suddenly, including muscle pain, irritability, and fatigue.


According to UCLA Health, caffeine narrows blood vessels around the brain which is why you can get headaches.

High blood pressure and heart rate

Coffee is known for increasing your blood pressure.

Still, elevated blood pressure is a risk for heart attack and stroke because it might damage arteries over time and restrict blood flow to heart and brain.

Your heart rate usually increases, too although the extent of the effects varies from person to person.

The British Heart Foundation’s dietitian Victoria Taylor explained: “While there is often concern about the links between caffeine and heart health, a moderate amount of tea or coffee (four or five cups a day) should be fine for most people.

“Research shows that this level of caffeine intake shouldn’t be detrimental to your heart health, affect your cholesterol levels or heart rhythm.”

Dehydration and fatigue

Once the caffeine leaves your system, you can experience an energy slump, as the NHS explains. Caffeine also stimulates the bladder, so increased urination is a common side effect – and that can also dehydrate you, making your fatigue worse.

Muscle spasms

Caffeine can cause muscle spasms, such as a nervous tic, a twitching eyelid or trembling hands.

Some people may struggle with muscle breakdown too, where damaged muscle fibres enter the bloodstream and lead to kidney failure and other problems, but as Healthline noted, this is extremely rare.

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