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Death by caffeine really is a thing, if you’re susceptible

Sadly, tragic news has emerged that a man in the United Kingdom recently died from caffeine overdose. John Jackson was 40 years old. What makes this unfortunate death worrying is that it was due to consumption…

A caffeine boost is part of the pleasurable effect of a good cup of coffee. Bug/Flickr

Sadly, tragic news has emerged that a man in the United Kingdom recently died from caffeine overdose. John Jackson was 40 years old.

What makes this unfortunate death worrying is that it was due to consumption of caffeine-laced mints. Misfortune can strike us in many ways, but we generally don’t expect a tin of sweeties to be our downfall.

I’ve written about death by caffeine before, but this particular tragedy involves a different aspect of one of the key themes of my blog and toxicology generally – the dose makes the poison.

How much is too much?

Everyone knows that caffeine is a stimulant and heightens alertness; this caffeine boost is part of the pleasurable effect of a good cup of coffee.

Caffeine also makes the heart beat faster and stronger, and high concentrations can cause severe heart problems (among other things), and even death. But despite widespread consumption of caffeine-containing drinks and caffeine pills, death by caffeine overdose is extraordinarily rare.

In this particular case, the deceased had consumed an entire tin of caffeine-containing mints. Each individual mint contained 80 milligrams of caffeine, about the same amount as in some moderate-level energy drinks.

Consuming the whole tin of the mints is like consuming 12 cans of a moderate-level energy drink, one after the other.

Sumeet Mulani

But is that enough to kill you? The handy website Death by Caffeine, where you can find out how many cans of energy drink, cups of coffee or bars of chocolate you will need to consume before expiring, suggests that a 70-kilogram person would need to drink 132 cans of a beverage containing 80 milligrams of caffeine (or a similar number shots of espresso coffee) to die of an overdose.

If that’s correct, then Jackson should have had a tenfold safety margin, so what went wrong?

Underlying susceptibilities

Sensitivity to caffeine and our ability to break it down varies between people. A recent report about energy drinks in the MJA found that people drinking no more than the recommended amount of energy drinks showed significant signs of toxicity (such as palpitations, and even parts of their heart muscle dying).

No one featured in the report actually died, but the average caffeine-containing energy drink consumption of people presenting to the emergency department was between three and eight cans.

These levels are on the threshold of caffeine intoxication, and should only be associated with mild symptoms. They demonstrate that some people are more susceptible to caffeine intoxication.

There are a number of reasons for this susceptibility, such as having an underlying heart condition. But in Jackson’s case, the most likely culprit was his liver.

Caffeine (and the related stimulants from tea and coca, theophyline and theobromine) is broken down in the liver by a specific enzyme (cytochrome P450 1A2 for the technical minded). Not everyone has the same amount of this enzyme in their livers for many reasons, such as the gene for the enzyme being missing or defective.

The reason you don’t give chocolate to dogs is that they have very low levels of their version of the human enzyme, and more susceptible to toxicity from theobromine and caffeine in chocolate.

Around 40% of Caucasians have a version of the enzyme that breaks down caffeine slowly. In these people, caffeine consumption is correlated with higher incidences of heart attack and high blood pressure.

Katy Stoddard

But in this case, the reason was not a genetic variation but disease. The deceased had cirrhosis of the liver, which, among other things, greatly reduces the ability of the liver to break down a variety of chemicals, including caffeine.

Better information

Jackson reportedly had 155 milligrams of caffeine per litre of his blood. But from the amount of caffeine he consumed, one would expect a blood level of somewhere between ten and 20 milligrams per litre, which is below the 80 milligrams per litre that’s reportedly toxic.

The mints in question have a label warning on the back of the tin saying they contain high levels of caffeine, and advise against eating more than five in a 24-hour period (but its website doesn’t have any warnings). The labels also warn caffeine-sensitive individuals against consuming them.

But most people with cirrhosis or hepatitis are not necessarily sensitive to caffeine, and so may not be aware that the warning applies to them. That is, if they read the back of the tin; the front of the tin makes no mention of caffeine at all, and consumers may not be aware they are eating caffeine-laced sweets.

There is, I think, a good case for more prominent labelling of caffeine-containing food stuffs and beverages, along with rewording of the warnings so they are clearer about who is at risk.

While death from caffeine overdose is fortunately very rare, this tragic case shows that there’s more we can do to make it rarer still.

Join the conversation

18 Comments sorted by

  1. Peter Ormonde


    Totally excellent again Ian.

    One of the few things that has concerned me of late is the breakfast of champions enjoyed by the lads of Woolibuddha who after another big night on the turps will knock down three or four restorative cans of energy boosting caffeine laced "soft" drink and a bacon and egg roll, then they don the hi-viz and head off to the timber mill.

    Young fellas might be able to get away with this till ldeveloping a scad of sense - less so folks who have done their liver a bit…

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    1. Ian Musgrave

      Senior lecturer in Pharmacology at University of Adelaide

      In reply to Peter Ormonde

      Yes, there are a number of factors in play here. Alcohol induced liver damage will reduce your ability to break down caffeine, as will age, which also reduces your ability to break down caffeine. Add those together and possibly some prescription drugs which inhibit caffeine breakdown and you are on your way to caffeine intoxication.

    2. Sue Ieraci

      Public hospital clinician

      In reply to Ian Musgrave

      The other factor operating here is the difference in style between cold drink consumption and hot coffee consumption.

      You don't see too many people tip up a mug of hot coffee and down it in one gulp, followed by another - and anyway, their neck would get scalded as it dribbled down.

      Cold, sweet, caffeinated drinks are marketed to be ''slammed down'' by young people - only increasing the speed of delivery of the caffeine dose.

    3. Jack Arnold


      In reply to Ian Musgrave

      HI Ian, great article, thank you. Do the same effects happen when kids drink multiple bottles of caffeine containing drinks like Coca Cola, especially the original formula that included cocaine to increase addictiveness?

      Also, when the caffeine effect is linked with high sugar consumption, reportedly about 12 teaspoons of sugar per can, what is the joint effect here?

  2. Christine Davis


    The website of the mints carries this information in para 3:

    HERO Energy mints are chewable mints that contain high levels of
    Caffeine (80mg), blended with Taurine and B vitamins. The active ingredients help to speed up your metabolism and sharpen your senses, which can increase your stamina and vitality.

    So there is information but if it's on the website and not on the front of the packaging then it is really obscure.

    How about the name of the sweets--and they make a point in para 1 that these are not overly sweet as energy drinks are.

    1. Ian Musgrave

      Senior lecturer in Pharmacology at University of Adelaide

      In reply to Christine Davis

      It doesn't have the warnings like "people with sensitivities should avoid, no more than 5 in 24 hours" etc. Which would be helpful as generally no one associates energy drinks with death.

  3. John Phillip
    John Phillip is a Friend of The Conversation.

    Grumpy Old Man

    Brilliant article, Ian. We do tend to think in terms of absolutes - the label this much is safe or a % of DRI so it must be ok - without thinking of the myriad variables we, as individuals, present. I guess it's like playing poker and trying to pick exactly what hand the other guy's got, when working with hand ranges is much more successful.Cheers

  4. Mike Brisco

    Scientist at Flinders University of South Australia

    Damned good article! I learned something today.

    I hadn't appreciated the link, between caffeine sensitivity, and liver damage, plus genes.

    Might share that with a friend or two. They had heart health-scares (palpitations) where the doctors thought caffeine was a suspect. None of us could work out why caffeine would do this to them, but not to others. We assumed the doctors were just passing on information about a known risk factor. But genetics and liver, might fit.

    1. Peter Ormonde


      In reply to Mike Brisco

      And I have more than a hunch Mike that the manufacturers of these "energy drinks" (and now breathfreshening mints @ 4 pounds sterling for 12) know full-well that they are being used as 'hangover cures' by a sizeable chunk of their most regular consumers ... hence the vitamin B ... the commerce of "common sense".

      Be an interesting bit of research that. I wonder if they'd offer up their market data... not bloody likely.

    2. David Arthur

      resistance gnome

      In reply to Peter Ormonde

      Does market research factor in people whose reading ability may not extend to the fine print?

  5. Donald Richardson


    It is great that you are entering the field of Arts+Culture, but I hope that the first thing you will do is recognise the moral rights of 'authors of artistic works' (as the Copyright Act styes artists and designers) by giving full acknowledgment for their works that you publish. And you could start by giving full acknowledgment to the person who made the work this article illustrates.

    1. Reema Rattan

      Editor at The Conversation

      In reply to Donald Richardson

      Donald, the author of the the images in this article have identified themselves with the names provided under the images, and have licensed their work as creative commons.

      What else would you have us include?

    2. Trevor Collison


      In reply to Reema Rattan

      The Main (Top) Image has no name(s) under it on my Browser (Chrome), only "Bug/Flickr"
      Presumably a Bug in Flickr?

    3. Reema Rattan

      Editor at The Conversation

      In reply to Trevor Collison

      The owner of the photo is identified as Bug on Flickr where the work appears.

    4. Trevor Collison


      In reply to Reema Rattan

      If that is how the artist wanted it attributed, that's great.
      However, I find it both obscure and difficult to follow up.

  6. Paul Richards

    integral operating system

    Great article, anything around coffee is a point of interest.
    This reminds me of the earlier inclusion of cocaine in coke promoted as a health tonic and extremely profitable. What is interesting is there is little coverage of corporate responsibility-CSR around this mint product.
    ".... highest quality energized ingredients to give you an immediate boost whilst sustaining performance at times of physical and mental exertion." **One Mission - part of the Hero corporate statement.
    The use of what…

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  7. Michael O'Keeffe


    Good article! I have had an adverse reaction to the energy drinks. I suffer a mild form of epilepsy that is effectively controlled by medication. However, if I drink any of these energy drinks, they cause me to have seizures. I suspect it's the vitamin b rather than the caffeine in them, because I'm fine with coffee, but multi-vitamins also cause seizures. Seems like there are an awful lot of 'foods' on the market that should really be treated like over the counter medicines.

  8. Graeme Smith


    Ian wrote: "Everyone knows that caffeine is a stimulant and heightens alertness; this caffeine boost is part of the pleasurable effect of a good cup of coffee..."

    Everyone knows this, sure, but why is that when caffeine "boost" for the most part simply treats people experiencing caffeine withdrawal and grants far less of a "boost" to those people who are caffeine naïve and so not in withdrawal? Prof Jack James may have provided an answer in the following quotes from an ABC programme I recalled…

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