Energy Drinks and Caffeine Toxicity (“The Good, The Bad and The Ugly”)

by Sheela Doraiswamy on October 1, 2012

I’d like to imagine that you read my advice last week, took it to heart, and swore to always get sufficient sleep. What you probably actually did was consider my advice, but then come across an ad like this one, that Red Bull is distributing on this very campus-

I do, actually, but that’s probably just me (photo taken by me)

Maybe they have a point–why bother with sleep when you can just drink a can of Red Bull, Monster, Rockstar, etc, and get almost the same effect?

A study published in Nutrition Journal(Maulinaskas et al)  looked at the behaviors, beliefs, and effects associated with energy drink consumption at a college campus. Another article published in the journal Clinical Nurse Specialist (O’Malley) provides a review of the negative side effects linked with energy drinks.

Let’s take a closer look at these articles and explore “The Good, The Bad, and The Ugly” of energy drinks- (feel free to listen to this while you read)

The Good: Increasing Cognitive Function

On the inside of that ad (pictured below), Red Bull says that their product improves performance and concentration.

photo taken by me

Well, the good news is that they’re not lying. As you probably know already, one of the main ingredients  in energy drinks such as Red Bull is caffeine. In small doses (about 12.5 to 50mg), caffeine has been found to improve cognitive performance and mood, and a higher dose of 200mg can increase cognitive task speed and alertness.

It makes sense, then, that the majority of students in this study said they consumed energy drinks due to insufficient sleep, to get energy for late-night cramming or working on a project, or to mask the effects of alcohol. It almost seems like energy drinks are a liquid solution to all your problems!

So 200mg of caffeine seems OK. That leads to a couple other questions- 1) How much caffeine is in an energy drink and 2) What happens when we drink too much?

This is definitely NOT what happens. Comic courtesy of Justin Boyd,


The Bad: Caffeine Toxicity

The amount of caffeine in an energy drink can range from 50 to 505 mg per serving (depending on brand, size, etc).  A large number of the students in Maulinaskas et al’s study also tended to drink more than one can at a time, and therefore were more likely to drink more than the recommended 200mg. Drinking high doses of caffeine can lead to caffeine toxicity, which can cause physiological and psychological problems.

One of the studies discussed in O’malley’s article tested the effects of a caffeine dose of 120mg versus 360mg on college students. Those who had consumed 360mg of caffeine from energy drinks had significantly increased blood pressure and heart rates, and all of them also experienced anxiety and insomnia.  In Maulinaskas et al’s study, about 22% of students also experienced headaches, and 19% had irregular heart beats.


The Ugly: The “Pharmacological Molotov Cocktail”

19% of students getting irregular heartbeats might not sound so bad. However, these effects are amplified when energy drinks are mixed with other substances, such as alcohol or certain medications (O’Malley refers to this as a “pharmacological Molotov cocktail”).

The mixture of energy drinks with medicines for ADHD and/or antidepressants can cause excessive stress on the kidneys, liver, and brain. A 2007 study referenced in this article even found that teens and young adults with eating disorders, or ADHD are at a higher risk for heart attacks or other heart problems after consuming energy drinks, possibly due to mixing high doses of caffeine with other medications.

We see similarly heightened negative effects when energy drinks are mixed with alcohol. Malinauskas et al’s study found that 73% of students did this so that they could mask the depressant effects of alcohol. In other words, they could drink seemingly without actually “getting drunk.” According to another study , students who mixed alcohol with energy drinks were 6 times more likely to have heart palpitations, and were also more likely to experience insomnia, anxiety, and tremors.


Energy drinks are relatively new, and there’s still a lot of research to be done on them as far as health effects go. If you want to use energy drinks, don’t just blindly drink several at a time. Look closely at the amount of caffeine and try not to exceed 200mg in one day. (Edited 10/3/2012 to include timeframe)

If you have any medical conditions discussed above, be aware that your risks are higher. And finally, remember that you increase your risk of heart palpitations, insomnia, anxiety and tremors by mixing an energy drink with alcohol.


Andrew Maynard October 1, 2012 at 7:29 pm

Interesting piece Sheela – especially the bit about energy drinks and ADHD medication. Was there any further information about specific medication, as it is far from uncommon for some pharmaceuticals here to be used off-label by students and others working to tight deadlines.

Sheela Doraiswamy October 2, 2012 at 8:37 am

Thanks, Andrew! The bit about ADHD meds is very interesting, unfortunately the articles I found didn’t go into much detail since there hasn’t been much research on the subject. These particular studies found that students with ADHD had a higher risk, and the researchers are hypothesizing that it’s due to the meds that they’re on. My guess would be that mixing high amounts of caffeine with any other stimulants would be dangerous.

Shara E. October 2, 2012 at 2:03 pm

On a purely anecdotal level, I definitely agree with the issues of ADHD and caffeine. I’ve found that I generally have a choice of either my ADHD meds or my morning Coffee, having both does not have a good outcome. I’d be curious to see what scans might show about the effects of caffeine in ADHD and non-ADHD individuals’ brain activity, but i think taht caffeine causes problems with PET scans in the first place…. oi.

Raji October 1, 2012 at 10:00 pm

Wonderful blog Sheela. Very informative.

Allie Sterling October 1, 2012 at 10:27 pm

Ha love your use of comics in this blog :) I believe that the drink Four Loko was actually banned because of the negative effects of combining alcohol + caffeine, right?

Sheela Doraiswamy October 2, 2012 at 8:33 am

thanks, Allie! Yeah, this comic strip is really great because they do a lot of them based on college life. And yes, I believe Four Loko was banned for that reason. Thanks for reading! :-)

Margaet October 2, 2012 at 12:38 am

Oddly enough I was surprised that caffeine actually has some good effects. I think this article is great for all college students. Is staying below the 200mg amount okay then? Is there a safe amount of caffeine? Interesting article, especially since energy drinks mixed with alcohol seem like they are especially dangerous.

Great topic, fun comic. Showed this to one of my roommates, who apparently loves redbull and Vodka. She said she would not mix them again. Thanks for the post! I look forward to next week’s healthier living by Sheela.


Sheela Doraiswamy October 2, 2012 at 8:24 am

Hi Margaret. I was actually pretty surprised, too, but one of the articles I cited did say that small doses can improve concentration. It seems like 200mg per day is alright, but I would also say that while it helps, it can’t really replace a good night’s sleep! I didn’t want the post to get too long, so I didn’t really go into exactly how long it helps concentration for and such. I’m considering doing another post on coffee and other sources of caffeine where I might go into those aspects a little more.

I’m glad I was able to convince your friend that mixing Red Bull and Vodka is not a great idea, too! Thanks so much for your comment!

Gern October 2, 2012 at 7:05 am

200mg in what time period? 200mg a minute? An hour? A day? A lifetime?

Sheela Doraiswamy October 2, 2012 at 8:24 am

Hi Gern. That was silly of me– the recommended amount is 200mg per day. Thanks for your comment

Elizabeth Fryer October 2, 2012 at 7:12 am

Hi Sheela,
I’m a LinkedIn connection of Andrew Maynard, and I’m a science editor/communicator.

You may have intentionally chosen the audience of those who work and study on your campus, but Andrew invited the rest of us to read your posts. Beware of exclusionary language like “on this very campus.” Readers want to be part of the club too. You could say “on the campus of the Univ of Mich—and likely on campuses across the United States.” Notice the difference in tone? Readers will think, “Yeah, those ads are on my campus too,” or “Those ads are probably all over the union at my alma mater,” and they’ll be in it with you and ready for the rest of the article.

Concerning “Those who had consumed 360mg of caffeine from energy drinks had significantly increased blood pressure and heart rates, and all of them also experienced anxiety and insomnia. In Maulinaskas et al’s study, about 22% of students also experienced headaches, and 19% had irregular heart beats.”

Data should be presented similarly, meaning, in this case, in percentages. But that also depends on your audience, some of whom may be turned off by a bunch of numbers. Also, when I first read “all of them also” I had to go back and read the first of the sentence. I can infer that all also had higher pressure and rates, but is that correct? 100% did? I’m not 100% sure, and you never want to leave your audience unsure or make your audience have to infer data.

Also, beware of using “significant” in science writing as it has a definite statistical definition. Were the increases in blood pressure and heart rates actually significant?

When a source has a name that spell-checker always underlines as misspelled, like Maulinaskas, you have to closely check each one. The post has at least one Malinauskas.

I found the info interesting and look forward to reading more.

Sheela Doraiswamy October 2, 2012 at 8:28 am

Hi Elizabeth. Thanks so much for all the feedback–I’m always looking for ways to improve my writing. Yes, according to the article I read, all the students who had 360mg of caffeine had higher blood pressure rates as well as insomnia and anxiety. And regarding the use of “significant,” I am aware that it has a statistical definition, and I make sure only to use the word if the original study did.

Thanks again- I’ll definitely try and fix those issues in the future.

kateb October 2, 2012 at 9:11 am

A high school near us has just opened a coffee bar in the school, and everyone is raving about it. I seem to be the only person in my area who thinks that life CAN be lived, and lived well, with proper sleep, and no caffeine. I am a professor, and get so tired of looking out at students who look half-alive. Why is it seen as the norm to live this way? The article in our local paper even said, “the high school students are acting more like college students now… they get their coffee, and sit with their laptops”…. (Sigh). Great post, btw!

Sheela Doraiswamy October 2, 2012 at 10:24 pm

I agree, people are way too dependent on caffeine. I might explore the subject further in another post, depending on what information I can find. I’m actually not a very big caffeine drinker myself– just the occasional tea. Anyway, thanks for your comment!

Rebecca Martin October 2, 2012 at 10:07 am

My ex once said he had two Red Bulls in one night and ended up lying in bed with his heart racing, and he could hear/feel it! Great article.

Smorg October 2, 2012 at 10:48 pm

You should do one on five hrs energy. It claims to have minimal caffeine. My ex-roommate swears by it. I think there’s something fishy about that thing, tho. It being a supplement also doesn’t help (the label isn’t regulated… who knows if what’s in the drink matches up with what it claims to contain anyhow?).

Sheela Doraiswamy October 3, 2012 at 12:53 pm

Thanks, I’ll look into it. A quick internet search does show that 5 Hour energy has about 200mg of caffeine. Just going by the caffeine content and the studies cited in the article, I think having one should be ok. I don’t know about the other ingredients, though. What’s interesting about that one is that it claims to not make you “crash” after a couple hours the way a cup of coffee does, so they could be putting some questionable stuff in there. I’ll see what else I can find on it

Anne October 4, 2012 at 3:27 pm

I wonder to what extent the marketing and social acceptance of energy drinks, particularly in teenagers, influences their likelihood of going on to use other substances like alcohol, marijuana, Rx drugs, etc, later on. Does consuming these in large amounts teach a pattern of behavior? I think the artificiality of these drinks (concocted in a lab, with high concentrations of caffeine) makes them inherently more dangerous and potentially abused than drinks from plants, like coffee and tea. However, I do recall that people had very negative feelings about excessive tea drinking in Britain when tea was introduced there.

bob husband October 5, 2012 at 11:05 am

Sheela, I’m a 59 year old enthusiastic science follower and love the site and your column (found it thru link in Scientific American ). I would point out as strictly as an observer of people that many people not on medication have very different reactions to caffeine. Back in the days of the dinosaurs, when I was in college, my toleration for caffeine with or without alcohal was pretty low. Rapid heartbeat, skipped beats, higher blood pressure and overheating were common. As I got older it got a good deal worse to the point where I would get dizzy and come close to blacking out before I got off caffeine altogether (typically this was a single large coffee only in the morning). The one thing perhaps you could follow up on was movements in the UK and some states to regulate these energy drinks. In NY the state attorney general’s office is investigating several manufacturers to determin the exact ingrediants.. and there was this article as well;

John C October 7, 2012 at 4:38 am

We need to be more aware that caffeine causes/exacerbates anxiety and other mental health condition.

Just read the 170+ pages of comments of people trying to get off caffeine here;
And the research referenced here;

Many people feel they cannot ‘get going’ in the morning without caffeine; in reality they are just experiencing withdrawal from not having ingested any over the previous hours.

A key point is the research showing anxiety sufferers can be very sensitive to caffeine; some people think ‘it can’t be the caffeine, I only have 1 cup a day’, but for them that could be the key issue in their anxiety.

Withdrawal is not easy (especially first 2 weeks, when anxiety actually goes up), but is possible.

How about cutting all caffeine for 30 days and seeing how you feel? Like this lady here is doing;

Jamie Weiser March 14, 2013 at 9:04 am

I have had multiple energy drinks in one sitting and there is nothing wrong with me. It might be the fact that I pretty much ran them off. But I am only 15 and I have ADHD.

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