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How much caffeine is too much caffeine? (Asking for a friend)

Updated: Oct 9, 2020

Empty coffee cups are piled on each other on a wooden table. On the left side, the title reads "How much caffeine is too much caffeine? Asking for a friend."

CAFFEINE - the lifeline of the working adult or stressed-out-student.

Caffeine and I became very cozy during my graduate studies when I started chugging coffee like it was my day job...for the longest time I thought coffee tasted like a car tire and that maybe I just wasn’t in on this sick joke that coffee actually tasted good. 

BUT I have been converted and now I wake up every weekday excited to indulge in the bitter taste of my morning coffee.

Although I may consider myself a newbie to the coffee game, caffeine consumption has occurred for thousands of years (most likely starting with teas). (1)

In North America alone, 80 percent of adults regularly consume caffeine. And our consumption has only increased in the past couple decades! In Canada, the average annual consumption of coffee increased from 96 L per adult in 1990 to 106 L per adult in 2009. (2)

Besides coffee and teas, caffeine is found in plenty of other foods and beverages including soft drinks, energy drinks, chocolate, and some medications and supplements like headache and cold remedies. It has even been added to certain gums, candies, mints, and water (???)! (3)

With caffeine being so popular and readily available, it is no wonder that it is the most widely consumed stimulant in the world. (1)

So what makes it a stimulant? And why does it leave me feeling ready to take on the day?

Caffeine is a central nervous system stimulant aka its happy place is the brain. Unlike so many other foods we consume, caffeine is rapidly and completely absorbed by the body, and begins to work its effects within 1 to 1.5 hours after we consume it. (1

When we consume caffeine we tend to feel more awake and alert, and ready to take on any task that requires our immediate attention. (4, 5) Caffeine has also been shown to improve physical performance and is often a common supplement used by high performance endurance athletes. (6)

How much caffeine we should consume has often varied from individual to individual based on our tolerance to caffeine and genetics - specifically whether we hold the genes that make us “fast metabolizers” of caffeine or “slow metabolizers” of caffeine. (1,3)

Despite these variations, Canada has created recommendations on how much caffeine we can safely consume before experiencing negative side effects.

Specifically, it is recommended that healthy adults should consume no more than 400mg of caffeine per day. 

But what does that look like?!

Well if you are a coffee drinker, one cup of your fresh brew can be anywhere between 80 to 180mg of caffeine, depending on the brand, roast, and brewing time of the coffee. (7) So consuming less than 3 cups of coffee per day should keep you in the safe zone.

Common sources of caffeine. Including caffeine in coffee, caffeine in specialty coffee drinks, and caffeine in teas.

And what if I consume too much? (You know...when I’m stressing for exams and such)

You may have very well experienced or heard of the “coffee shakes” - when people feel they could start bouncing off the walls.

But too much caffeine can also lead to increased heart rate, anxiety, upset stomach, diarrhea, and insomnia. (8)

If you are frequently experiencing these symptoms, it’s best that you slowly cut back on your consumption of caffeine. 

Some tips on how to achieve this include:

  • Gradually reducing your intake by one cup every couple of days. By gradually reducing your intake, you will be able to limit any negative withdrawal symptoms. 

  • Choose beverages that are lower in caffeine. If you enjoyed the taste of coffee, try swapping one of your coffees for decaf. One cup of decaf coffee has about 3-15mg of caffeine - far less than the 80-180mg found in one cup of brewed coffee. (7)

  • Make water your drink of choice. To quench your thirst, turn to water before any caffeinated beverages. 

Bottom Line: Everyone is affected by caffeine differently. To play it safe, stick to Health Canada’s recommendations of 400mg of caffeine per day.


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