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Caffeine Addiction 101

Updated: Jul 25, 2021

The Signs and Consequences of Caffeine Addiction

Caffeine addiction is usually indicated by a variety of symptoms, including a persistent desire, but the inability to control caffeine intake, withdrawal, caffeine tolerance, and cravings [8].

Author: Alison MacPhee

What is Caffeine?

Caffeine is classified as the world’s most popular psychoactive drug [1]. It is legal and unregulated, but is still considered a drug as it stimulates the body’s central nervous system [1-3]. In fact, approximately 80% of North American adults are regular users of caffeine [1]. It can be found in a wide variety of products and substances, including coffee, tea, chocolate, cola drinks, energy drinks, and even some over-the-counter and prescription medications, so it is important to be wary of its prevalence [1,4-6].

From a scientific perspective, caffeine is a substance that is both water- and fat-soluble, which enables it to travel through the bloodstream and pass through the blood-brain barrier, into the brain [3]. The chemical structure of caffeine also happens to be very similar to adenosine, a naturally-occurring compound in the brain that makes us feel tired [3]. Caffeine binds to the adenosine receptors in the brain and essentially blocks adenosine from binding, preventing the feeling of tiredness [3]. To compensate for this, the brain makes more adenosine receptors, causing regular caffeine users to require progressively more caffeine to feel alert [3].

The above image illustrates the variety of products that caffeine is present in, and in what quantities [7].

How Does Caffeine Affect the Body?

Caffeine can have a variety of effects on the body, but if consumed in moderation, it stimulates the brain where the user feels more alert, has an elevated mood, and less frequently occuring feelings of fatigue [1,3-6,8,9]. Most healthy adults can safely metabolize approximately 400mg per day, which is roughly equivalent to four standard cups of coffee [3,4]. The recommended intake varies from person to person and depends on gender, weight, age, caffeine sensitivity, and medical conditions [2,4]. For instance, children and pregnant women should limit their caffeine intake, as it increases heart rate and blood pressure, while teens and young adults should be educated on the importance of not mixing caffeine with alcohol [4]. This is because although caffeine makes you feel more alert, alcohol still impairs your coordination and concentration, and you may be unaware of how much alcohol you are truly consuming [1].

Signs of a Caffeine Addiction & How to Overcome It

Although caffeine can be used in a healthy manner, it can cause more serious effects on the body when the user does not monitor their intake. Heavy caffeine use may cause headaches, insomnia, anxiety, irritability, frequent urination, increased or irregular heart rate, or muscle tremors [1,4,6,9]. In fact, 5000mg of caffeine in a short period of time can even be fatal [1]. Thus, much like smoking cigarettes, when a person with caffeine addiction does not consume their usual amount for the day, they may experience many of these symptoms in addition to fatigue, depressed mood, low energy, and difficulty concentrating [3,5,8,9].

There are many side effects that may be a result of heavy caffeine use or withdrawal, including headaches [10]. 

Caffeine Addiction

Caffeine addiction is usually indicated by a variety of symptoms, including a persistent desire, but the inability to control caffeine intake, withdrawal, caffeine tolerance, and cravings [8]. A full list of indications can be found in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition [8].

Fortunately, there are several tips and tricks that can be used to curb caffeine addiction. However, it is crucial to work towards gradual recovery to avoid any potential withdrawal side effects [2,4,5,9]. When dealing with a caffeine addiction, it is recommended to increase one’s water intake and incorporate exercise into one’s daily routine [5,9]. Start by replacing one caffeinated drink with a decaf version every day, then progressively increase this amount [4,5,9]. For example, replace one caffeinated tea with an herbal tea instead [5]. Eventually, your brain will return to producing its baseline number of adenosine receptors, and you will become less dependent on caffeine to get you through the day [3]. Overall, it is possible to get through it, and your adenosine receptors will thank you for it.


Jasmine Kokkat, Winnie Lui, Mouayad Masalkhi, Rhea Verma


Web design by Majd Al-Aarg

Additional Credits

Cover photo provided by Karl Fredrickson on Unsplash


  1. CAMH [Internet]. Toronto (ON): Centre for Addiction and Mental Health; c2020. Caffeine; c2020 [cited 2020 Nov 18]. Available:

  2. Teens Health [Internet]. Jacksonville (FL): Nemours; 1995. Caffeine; c2020 [updated 2014 Sep; cited 2020 Nov 18]. Available:

  3. Addiction Center [Internet]. Orlando (FL): Addiction Center; c2020. Caffeine addiction and abuse; c2020 [cited 2020 Nov 18]. Available:

  4. Mayo Clinic [Internet]. Rochester (MN): Mayo Clinic Staff; 1998. Caffeine: How much is too much?; c2020 [cited 2020 Nov 18]. Available:

  5. Healthline [Internet]. San Francisco (CA): Healthline; c2020. What happens after I cut off caffeine?; 2017 Jun 22 [updated 2017 Jul 14; cited 2020 Nov 18]. Available:

  6. Healthline [Internet]. San Francisco (CA): Healthline; c2020. The effects of caffeine on your body; 2017 Aug 7 [updated 2018 Sep 28; cited 2020 Nov 18]. Available:

  7. Canada R. Amount of caffeine per cup [Internet image]. 2013 [cited 2020 Nov 18]. Available from:

  8. VeryWell Mind [Internet]. New York (NY): About Inc.; c2020. Caffeine addiction symptoms and withdrawal; c2020 [updated 2020 Mar 23; cited 2020 Nov 18]. Available:

  9. Cleveland Clinic [Internet]. Cleveland (OH): Cleveland Clinic; c2020. Caffeine: Tips for breaking the habit; 2014 Jul 13 [cited 2020 Nov 18]. Available:

  10. Rivers, A. Caffeine overdose symptoms [Internet image]. 2018 [cited 2020 Nov 18]. Available from:

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