caffeine head pic


Caffeine is one of the most widely used drugs in the world. The Red Bull girls kicking around uni are great but do they don’t really need to work that hard to sell students caffeine. It’s almost a degree requirement to maintain a healthy caffeine addiction these days. And don’t forget tea. There is nothing more British than sitting down in front of Countdown with a nice cuppa and a couple of biscuits. If you are not a tea lover (heresy) every coffee shop is jumping to sell you caffeine in the disguise of mochas, frappes and skinny lattes. A caffeine pick me up is never far to be found but is all that caffeine good for you? It may keep you awake during a boring lecture or help you push through the last two hours of writing that essay at 4 am but what are the long term effects of caffeine on the body? Dr. Wellgood is here to give you the lowdown.

+   What is it?

Caffeine is the common name used for the stimulant trimethylxanthine. Though legal, caffeine shares traits with many other stimulants such amphetamines, cocaine and heroin. Just like with those other drugs caffeine can have an addictive effect making it hard to give up. A small daily dose of caffeine shouldn’t do you much harm but too much can have a negative effect on your body.

+   What is it in?

Caffeine is hiding everywhere, in places you probably don’t even expect. It can be naturally occurring in food or it can be added to food by manufacturers. You can always check the ingredients label if you want to find out whether foods contain caffeine. Some of the most common sources of caffeine include:

  • Coffee
  • Tea
  • Chocolate (to varying amounts)
  • Fizzy drinks
  • Energy drinks
  • Weight loss pills

+   Effects

Caffeine can have both negative and positive effects on the body. In the short term caffeine can make you feel great. It affects adenosine uptake in the brain making you feel more alert. It injects adrenaline to give you a bit of a boost and manipulates dopamine production making you feel all good. But what do all these fancy chemical names mean?

Adenosine is a chemical that is created in the brain and aids with sleep. It does this by connecting to nerve receptors and slowing down cell activity causing drowsiness. Caffeine fools nerves into thinking it is adenosine and binds to receptors in its place. This prevents adenosine from binding to the nerves and slowing you down.

At the same time caffeine causes increased neuron firing and the brain responds to this by releasing adrenaline. Adrenaline is what your body produces when it thinks there is an emergency to respond to causing your body to

  • Open your airways
  • Make your heart beat faster
  • Increase your blood pressure
  • Get your liver to release extra energy
  • Tighten your muscles

Finally caffeine prevents the re-absorption of dopamine. When dopamine floats around it activates the pleasure centers of the brain so when caffeine stops it from being reabsorbed the levels rise and you feel happy.

+   Long term consequences

The short term effect of caffeine can feel great and there are some possible medical benefits to caffeine. However, there are some potentially unpleasant and even dangerous side effects of too much caffeine.


The positive effects of caffeine can be addictive in themselves. They may also lead to a dependence cycle. After the initial adrenaline rush caused by caffeine wears off you will hit a slump and you may feel like you need another boost of caffeine to get you through the end of the day. If you are dependent on caffeine you may also suffer from withdrawal symptoms. These symptoms will often appear 12-24 hours after you last had caffeine and can last up to 9 days:

  • Tired
  • Headaches
    • Withdrawal will cause headaches as caffeine constricts blood vessels in the brain. When you withdraw from caffeine the blood vessels will expand possibly leading to headaches.
  • Depression
    •  The effects of newly reduced levels of dopamine
  • In extreme cases of withdrawal you may find that you get nausea or vomiting

Sleep Disturbances

As caffeine affects the uptake of adenosine which aids with sleep it can mess up your sleep cycle.  Caffeine will stay in your system for around 6 hours so if you have it later in the day it can affect your sleep. Though you may fall asleep the lack of adenosine may mean the sleep is not a deep sleep. Eventually you will fall into a cycle where the lack of deep sleep will cause you to crave more caffeine the next day. 


Caffeine is a diuretic which means it will make you pee more frequently. If drink nothing but coffee you will probably end up dehydrated. If you are already slightly dehydrated you should probably avoid caffeine and you should drink water.

+   Short term effects

If you consume too much caffeine in the short term especially if you are not used to it you may notice a few short term side effects:

  • Rapid heart beat
  • Dizziness or light headedness
  • Nausea
  • Jittery or shaky

Possible Benefits

Caffeine isn’t all bad and it can be medically useful in a number of situations:

  • Caffeine’s side effect of stimulating adrenaline in your body causes your airways to open. For asthma patients caffeine can be used in emergencies if they don’t have their inhaler and they are struggling to breathe
  • Caffeine has also been shown to increase the effectiveness of aspirin and paracetemol and it is often included in cold and flu medicine
  • Caffeine may help with migraines as it constricts the blood vessels in the brain however, it can also cause headaches so should be used with care
  • Recent studies showed that drinking 1-3 cups of coffee a day reduces your risk of contracting diabetes by about 9%

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