Caffeine overdoses: know your dose!

Sci would like to note that I'm writing this post while I'm sipping my first cup of coffee for the day. Irony, thy name is caffeine addiction.

So the other day I was out with my running partner, and she mentioned that someone had DIED from caffeine overdose. At first, I thought it must have been a Redbull and vodka thing, but nope. PURE CAFFINE. I got a copy of the article, but then Mo tweeted about it and I knew I had to blog it, at least a little.

First off, that was a really stupid thing to do. But the second question is WHY. A lot of people were very confused. And so I figured, being caffeine's patron saint like I am, I gotta tell you that this stimulant is a double edged sword.

But it's still a lot of fun to wear. 🙂 And nice to drink. Just...not in insane quantities.

The fact is, a lot of things can kill you if you take enough of them. Alcohol is one of the most well known examples, nicotine is another (most people think long term, but you can actually die from large acute doses, which are very toxic). Heck, you can die of too much Tylenol!

But today we're talking about caffeine. Overdoses on caffeine are REALLY rare. This is mostly because, in the way we take it normally, you wouldn't have time to take enough before the side effects (shakiness, paranoia, anxiety, racing heart, high blood pressure, etc) were enough to make you stop. And the fact is, it takes a LOT of caffeine to kill a guy, and most of the time we take it in very small doses. For example, the average cup of coffee contains between 80 and 200 MILLIGRAMS of caffeine. An average caffeine pill contains 100 (or 200 for extra strength). Because the numbers are in the hundreds, that sounds like a lot, but it's not. 200 milligrams is actually around 0.025 teaspoons of caffeine (going by the conversion of one teaspoon being about 5 grams dry weight of substance, but I'm not sure that's accurate).

Suffice it to say that the guy who died from the overdose didn't know enough about what he was taking. You can BUY powdered caffeine on the internet, but it also comes with a clearly stated dose of taking no MORE than 1/16 of a teaspoon. That's going to be one heck of a buzz, but not deadly. This man either didn't see the label (very likely), or wasn't sure how potent caffeine is (also likely). The news articles say he took two large spoon fulls (and then washed it down with an energy drink), which may be as much as 20 grams (if they were tablespoons, not teaspoons). That's a LOT. Several hundred times the normal dose. I'm not going to go into the heavy pharm (it's only my second cup of coffee right now), but that's a LOT. The lethal dose in rats is 192 milligrams per kilogram, and let's say the guy weighed 200 lbs or 90 kilos. He would have to take 17,280 milligrams, which is about 17.2 grams. However, that's NOT taking into account the fact that humans are very different from rats and metabolize drugs, in general, MIUCH more slowly, which means we can die from much lower doses. Overdoses in humans (requiring hospitalization, but not death) have been seen with doses of only 2 grams.

But what I want to go into here is: what did he die OF?! Well, probably heart issues. People near him observed him vomiting blood and sweating profusely. Caffeine has very strong effects on the heart and blood vessels. Even a cup of coffee increases blood pressure and causes constriction of blood vessels in the brain (though it's minor). In the heart, caffeine increases heart rate, partially by acting as a mimic of the transmitter epinephrine. Death by caffeine (seen in animals) is usually caused by something called ventribular fibrillation. This is where the ventricles of the heart lose their rhythm and stop pulling together. You get uncoordinated contractions, and the whole thing stops pumping and looks like a quivering mass.


Obviously this is not very effective at, you know, getting blood places. Like the brain, or the lungs. Or anywhere else important. Death results. You can sometimes use a defibrillator to shock the heart back into a normal rhythm, but of course in order to do that, you have to know what's going on and have them handy. But who's going to know that at a party?

Poor guy. He didn't know. But now YOU know. Caffeine IS safe in small doses (caffeine pills, cups of coffee, etc). But know your dosing.

This gets to something that bugs Sci a lot, actually. It's one of the reasons I started blogging, and one of the reasons that I feel so strongly about getting the word out about drugs and their effects. Sci was doing outreach to a bunch of middle schoolers one day. She was telling them about various things they wanted to know (I usually just ask what they want to know, they have a lot more fun than if I give a lecture). I'm very honest about what drugs can do, what we know from the science, etc. And one girl asked about a drug, I don't remember what it was (might have been meth), but it made my eyebrows shoot straight up to my hairline. She came up to me privately afterward, and nervously confessed that she had done some of it, and was she going to die? Was it ok? Her boyfriend just gave it to her and she just...y'know...

And I got SO MAD. Not AT her, obviously. But at the people who kept her ignorant, who gave her drugs without telling her what they were. Who made her feel like she should take them. I told her "you have a RIGHT to know what goes into your body. Whether it's food, or drugs, or anything else. It's YOUR body and you have a RIGHT to know what it is, and what it may do to you." She looked so shocked. It clearly had never occurred to her that she had a right, indeed she owed it to herself, to know what she was putting in to her body. And then she asked how she could do what I do when she grew up. I might have teared up a little.

So, when you're at a party, and you're doin' whatever (and that's not for me to determine), you should KNOW what you're doing. Know what you're taking. Know what it will do. And I'm not talking about what your friends say it will do. Look it up, and learn to tell the difference between what's good information and what's not. You need to know what drugs will do to you, it's why prescription drugs come with huge long lists of side effects and drug effects and etc, etc, so you can read it, and know what you're taking.

But a cup of coffee is probably still ok.

18 responses so far

  • Craziness.
    Drugs (or their physiological effects) are not my specialty, but I think that simple basic chemistry classes illustrate that taking ~100mg of caffeine is a huge difference from ~10g of the stuff.
    All the more reason that science matters, despite what politicians and religious fanatics think.

    BTW, how do you get the gigs talking to students? When I'm done with classes, I wouldn't mind doing that; I'd love to show kids how weird microorganisms can be and how most of them aren't going to kill you.

    • scicurious says:

      It was through my grad school, which did a Brain Awareness Week via the Dana Foundation. I don't know about other outreach methods, unfortunately.

    • Abby says:

      I do a lot of outreach teaching through this local program: . There's a fledgling national organization, that's supporting people who want to get similar programs running at universities across the country.

    • Lori says:

      This is great, thanks!
      Doallthescience- it makes no sense that you have to bash people who love God that gave something for people like you to do. I am all for science but it is not my God and creator of all things. Ridiculous comment. Great post:)

  • Epicanis says:

    When I saw this story pop up on Reddit, I went and looked up the density of (pure) caffeine, did some conversions, and came up with a guess of around 6-7 grams of caffeine in the dose he took, depending on how fine or densely-packed the powder was (still way too much obviously, even by my own "too much blood in my caffeinestream" standards...)

    • scicurious says:

      Hmmm, yeah, that conversion sounds better than my early AM pre-second cup of coffee calculations. I can look it up maybe...Still considering people get hospitalized for 2 grams, 6-7 is WAY too much.

  • I dig the last 3 paragraphs. Drugs (legal or illicit) are always risky, but they don't have to be as dangerous as they end up being when taken by people who don't know (and, perhaps, don't bother to try to find out) what they do.

  • PalMD says:

    I'd agree that cardiac arrhythmia seems a likely mode of exit, but the vomiting blood is intriguing. If we posit that high doses of caffeine can cause vomiting, the simply retching can cause tears in the esophagus and some mild bleeding. If there were pre-existing lesions, such as esophageal varices or ulcers, the increase in blood pressure could have lead to significant, life-threatening bleeding.

    And of course, he may have aspirated his vomitus and died from asphyxiation.

    • scicurious says:

      It IS really interesting, I didn't know what to make of it. There are gastrointestinal disturbances associated with high caffeine intake. Other options could also be the muscle spasms, maybe? He definitely suffered incoherence, which is one of the symptoms of caffeine intoxication, so the gastrointestinal could be there too. I didn't know why the blood, though. The ulcer is a good guess.

  • Stephanie Z says:

    Slightly ironic that today is the day my caffeine Scicurious t-shirt should arrive in the mail, but this whole post, and particularly those last paragraphs, amply demonstrate why I'll be proud to wear it.

  • Craig says:

    My PI was wandering around in one of those caffeine shirts the other day...


    "So, when you’re at a party, and you’re doin’ whatever (and that’s not for me to determine), you should KNOW what you’re doing. Know what you’re taking. Know what it will do. And I’m not talking about what your friends say it will do. Look it up, and learn to tell the difference between what’s good information and what’s not. You need to know what drugs will do to you, it’s why prescription drugs come with huge long lists of side effects and drug effects and etc, etc, so you can read it, and know what you’re taking. "

    So: where would you recommend they start? The peer-reviewed psychopharm literature is of limited use to a lay audience, and just letting folks loose on the internet without first teaching them how to distinguish good info from bad is asking for disaster.

    I usually poke folks towards and, but both of those require the reader to bring a generous pinch of salt; there's a lot of good info on there, but also plenty of dodgy. Got anything better?

    • scicurious says:

      I actually often direct people to Erowid, because though there's dodgy stuff, they are pretty accurate on things like dose and side effects.

      Pubmed actual papers may be off limits, but the abstracts aren't, and they can at least give you a good idea of what's going on. WebMD has many of the prescription drugs listed. Even Wikipedia (though it's not always accurate) often has sources listed you can go to which will start you out.

  • Samantha Vimes says:

    I actually was giving myself mild caffeine poisoning my freshman year of high school. I ended up quitting it until asthma attacks made me rediscover the healing side of it. But I became rather fascinated by toxins-- a lot of people think it's disconcerting, but it is a useful study for safety.

  • Ana says:

    my limit are tree cups of coffee per day
    it's unhealthy plus I don't even feel the caffeine effect if I drink more than that

  • [...] (un cafĂ© cargadito tendrĂ­a 200mg de cafeĂ­na), y sĂłlo con 2 gramos irĂ­as directo al hospital. Scicurious tiene más detalles de cĂłmo se muere uno por sobredosis de cafeĂ­na (en inglĂ©s) pero yo querĂ­a [...]

  • ecstatist says:

    Paraclesus (I think) stated that everything, in a small enough dose is non-toxic, beneficial, or possibly even essential AND everything in a large enough dose will kill you! Even water! The absurd limit is drowning, but "electrolyte" dilution causing nervous cardiac fibrillation or blood pressure disturbance has killed many a long distance runner when the advice was to drink as much as possible. Present advice (I think) is listen to your body and/or ensure that you do not urinate large quantities, regularly (measured over many hours) more than every 90-120 minutes AND beware if you cease episodic urination or the urine is very yellow. If you feel very hot but are not visibly sweating, drink. Rather err on the side of too much water.
    Theoretically 1 atom of plutonium can kill you by causing cancer. This is a man made ("unnatural") chemical and there are others that are not radioactive but highly toxic, mainly because organisms have not evolved mechanisms (excretion or alteration to a benign molecular form) to deal with them so that even tiny quantities can cause significant (fatal) damage over time. A "natural" example is asbestos. Toxicity levels can be expressed as one time dosage (mg per kg) or long term (mg per kg per day etc)
    The "benefit" or "necessity" aspect is often difficult to test because many substances are ubiquitous and/or it is impossible to provide a test environment that is absolutely free of that substance.
    Nevertheless (without splitting hairs) Paraclesus's statement is an important concept to understand. Unfortunately life is not simplistic.

  • Ben Ward says:

    Hello Sci,

    I found this post in my online seeking to make sure that I did not kill myself with caffeine. I started trying to extract a saturated coffee solution which, at room temp, would be about 20g/L which is about enough to kill a rat of my size.
    I got the idea from the "Black Blood of the Earth" coffee people and cause I'm cheap I wanted to make it myself.
    Well it turns out that it is only about 4g/L of caffeine, via HPLC, but it is enough to get me good and well addicted.

  • Ilovepigenetics says:

    A really good site to teach about how drugs affect your brain is the University of Utah Mouse Party website.

    I use their Science Education videos for a variety of teaching opportunities, even grad students.

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