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Monday Article #10: Caffeine Withdrawal- Why do you feel the effects and how to minimize it.

Have you ever noticed side effects when trying to stop drinking coffee after having it regularly? This is called caffeine withdrawal syndrome.


Caffeine is a methylxanthine class stimulant that stimulates the central nervous system (CNS). This is achieved by acting as a competitive adenosine receptor antagonist and block the endogenous adenosine in the brain. Adenosine in the CNS is a neurotransmitter that can regulate sleep and cause drowsiness, thus, by blocking the action of adenosine, caffeine can cause the drinker to be more awake and alert. Caffeine in the form of coffee is the most common psychoactive substance consumed by the population but other forms of caffeinated drinks can include tea, green tea, energy drinks and cola-type caffeinated soda. Food that contains caffeine include dark chocolates and some supplements.

Once caffeine is consumed, it is rapidly absorbed into the body within 45 minutes and the peak plasma concentration are achieved between 15 to 120 minutes. The average half-life of caffeine is 5 hours, meaning that after 5 hours, half of the caffeine consumed is still in the body. However, the half-life of caffeine can range from 1.5 to 9.5 hours depending on individual and one’s lifestyle such as smoking and obesity.

Symptoms of Caffeine Withdrawal

Caffeine withdrawal occurs when an individual who consume caffeine regularly stops consuming abruptly. The symptoms can start between 12 to 24 hours. Typically, an individual can feel the peak withdrawal effects between 24 to 54 hours and the effects will last from 2 to 9 days.

Caffeine withdrawal syndrome is a clinically relevant diagnosis and is included in the Diagnostic and Statistical Manual of Mental Disorders. Symptoms of caffeine withdrawal can vary from individual to individual and its severity can be mild to clinically significant distress. The most common symptoms are headaches, fatigue, anxiety and mood changes.


Caffeine reduces blood flow in the brain by an average of 27% by constricting the blood vessels. This is known as vasoconstriction. When caffeine intake is stopped, the constricted blood vessels expand (vasodilation) and blood flow increases. As a result, the brain needs to adapt to the increase in blood flow which causes the headache. Studies have shown that the occurrence of headaches is around 50% while significant clinical distress is 13%.

Fatigue and Low Energy

As mentioned earlier, caffeine blocks the adenosine receptors to increase alertness and prevent drowsiness. Studies have shown that high caffeine intake can increase one’s tolerance to caffeine by upregulation of adenosine receptors. Without caffeine, there are more receptors for adenosine to act on, thus, causing one to feel fatigue and have low energy. Upregulation of adenosine receptors is also one of the reasons why people who consume higher amount of caffeine experience more effects from caffeine withdrawal.

Mood Changes and Anxiety

Other than blocking adenosine receptors, caffeine can stimulate the release of hormones such as adrenaline and cortisol as well as the increase of neurotransmitters such as dopamine and noradrenaline. These hormones and neurotransmitters can stimulate the rewards system in the brain and the ‘fight or flight’ response. Therefore, caffeine withdrawal can affect the mood and cause negative emotional effects like anxiety.

How to Reduce Caffeine Withdrawal Symptoms

The good news is that caffeine withdrawal symptoms can be reduced if the appropriate steps are taken. One example is to cut back caffeine slowly. Cutting caffeine cold turkey is never a good idea as the effects of caffeine withdrawal can come in full force. A good way of cutting caffeine slowly is to reduce the intake of caffeine by 10% every 2 weeks. Although this may take a while, but the effects of caffeine withdrawal will not be as noticeable. One can reduce caffeine intake by reducing the drink strength or the number of cups of caffeinated drinks.

Similarly, keeping a food/drink diary while cutting back caffeine is beneficial in terms of making sure that one does not over consume caffeine. Checking the labels of supplements, packaged food or drinks prevents the consumption of caffeine unintentionally.

Another way of reducing caffeine withdrawal symptoms is to always stay hydrated. This is due to the fact that dehydration can cause the symptoms such as headaches to worsen. Getting between 7 to 9 hours of sleep a night is also helpful for the body as well as being able to combat the feeling of tiredness.

In conclusion, caffeine is an adenosine receptor antagonist that increases alertness. However, abruptly stopping the intake of caffeine can cause caffeine withdrawal symptoms such as headaches, fatigue and mood changes. Caffeine withdrawal symptoms can be reduced by cutting back caffeine slowly, staying hydrated and getting enough sleep.


This article was prepared by Jennifer Chang


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