Exactly what that cup of coffee does inside your body minute by minute (and yes, it DOES have a laxative effect)

For many of us, that morning coffee is an essential part of our daily ritual.

But have you ever wondered what exactly happens inside your body after taking that first sip? 

Here, MailOnline breaks down precisely that…

Have you ever wondered what exactly happens inside your body after taking that first sip

Within the first ten minutes… 

Coffee starts kicking in just 10 minutes after the first sip.  

Dr Duane Mellor, of the British Dietetic Association, claims this reflects how quickly caffeine is absorbed into the blood stream by parts of the digestive system.

‘After drinking a coffee the caffeine will start to appear in blood after about 10 minutes,’ he said. 

‘Some can be absorbed through the mouth and stomach but only smaller amounts, most of the absorption is in the first part of the intestines.’ 

Once the caffeine in the coffee is absorbed, that’s when you feel that tell-tale energy boost.

What contains caffeine and how much is safe to drink?

  • Coffee, tea, colas and energy drinks contain high amounts of caffeine. 
  • Caffeinated drinks are unsuitable for toddlers and young children
  • Pregnant women should have no more than 200mg of caffeine a day because high levels of caffeine can result in babies having a low birthweight
  • The NHS suggests that more than 600mg of coffee per day (six cups) is too much and can lead to anxiety, sleeplessness and palpitations 
  • One mug of instant coffee contains around 100mg of caffeine
  • Energy drinks can contain 80mg of caffeine in a small 250ml can. This is the same as two cans of cola or a small mug of coffee
  • The NHS advises that tea and coffee is fine to drink as part of a balanced diet
  • But caffeinated drinks can make the body produce urine more quickly 


This boost is a bit misleading, however. Caffeine doesn’t actually provide energy.

Instead, it works by blocking your body from interacting with adenosine, a chemical lurking inside us which makes us feel tired. 

Caffeine works this way because its chemical structure closely resembles adenosine, fitting like a key in a lock to adenosine receptors in the body. 

This prevents us from feeling tired, naturally making us more awake.  

After 20 minutes…

Caffeine blocking the body’s adenosine receptors doesn’t just promote wakefulness, Dr Mellor explains.

It is also thought to trigger a hike in blood pressure within half an hour of drinking coffee — and the effects can still be seen roughly four hours later.

This spike in blood pressure is caused by caffeine causing your blood vessels to constrict consequentially increasing heart rate. 

While temporary, the NHS warns that drinking more than four cups of coffee per day may increase your blood pressure in the long run. 

After 45 minutes…

The effects of caffeine on the body peaks at 45 minutes, Dr Mellor said.  

The stimulating effect of coffee, the increases in your heart rate, and sense of energy energy, improves both concentration and memory. 

But drinking too much coffee can have detrimental effects.

Too much caffeine, instead of helping you focus, makes you feel jittery or anxious. 

NHS guidelines say around 400mg of caffeine a day is safe for adults, the equivalent of four regular cups.

Pregnant women are advised to consume around half that, while the recommended limit is around 100mg for teens.

After 60 minutes…

After the stimulating effect of caffeine kicks in, you may notice an unwanted side effect.

Once caffeine appears in the blood it will start to have what experts call a diuretic effect, Dr Mellor says.

That means if you drink enough coffee it can make you need to urinate more than usual. 

Just 10 minutes after drinking a cup of coffee you can start to feel it waking you up, an effect that can last for about an hour

Just 10 minutes after drinking a cup of coffee you can start to feel it waking you up, an effect that can last for about an hour

When you drink coffee the caffeine in the drink inhibits the production of the anti-diuretic hormone or ADH, which usually helps regulate the amount of water in your body, according to the NHS. 

This causes the kidneys to not reabsorb water and increases how much you wee. 

But you would need to drink a lot of it to become dehydrated.  

Research shows that for coffee to have an impact on your hydration levels you would need to be drinking more than 500mg of caffeine a day, or more than five cups. 

A 2014 study by the school of sport and exercise at University of Birmingham, found no evidence of dehydration with moderate daily coffee intake. 

The NHS also says drinking caffeine in moderation is a good way of staying hydrated, along with water, squash and juice. 

But coffee doesn’t just make you need to pee more, you may also notice it stimulates the urge to poo. 

Studies have shown that coffee can activate contractions in your colon and internal muscles. 

A 1998 study suggests that caffeine makes the colon 60 per cent more active than water.

It’s these contractions in the colon push the contents towards the rectum. 

After 90 minutes and beyond 

The time it takes for caffeine to metabolise varies from person to person.

But, for most people, an hour or two after the first sip of coffee the simulating effects start to fade, as well as the diuretic effects, according to Dr Mellor. 

This can cause feelings of tiredness, anxiety and poor concentration.

However, just because you feel a caffeine slump doesn’t mean it has fully left your system.

‘For most people the amount of caffeine falls by around half after six hours as it is metabolised by the liver, so although the effects may feel that they wear off after an hour or two there will still be plenty of caffeine in your system,’ he said. 

As a result, caffeine can hang around in your body for up to 12 hours, according to researchers at the organisation Sleep Foundation. 

It adds that many sleep experts recommend avoiding caffeine at least eight hours before bed time so it doesn’t interfere with your sleep, meaning it’s best to avoid an afternoon brew.

Read more at DailyMail.co.uk