Beware of energy drinks

With increasing numbers of young people turning up to hospital after downing too many energy drinks, Professor Chris Semsarian discusses the potentially dangerous side effects.

Improved awareness of the potential dangers associated with energy drinks is of great importance was the key recommendation made by myself along with my colleagues Dr Belinda Gray and Dr Jipin Das in a letter to the International Journal of Cardiology.

In writing our letter we looked at more than 10 recent papers that all highlight the growing concern among cardiologists and other health specialists about the rise of energy drinks and the increase in negative events following their use.

I’ve also been quoted along with other health professionals and researchers in a recent Men’s Health article on this issue and I wrote an article for research news site The Conversation.

Warnings for high-energy drinks

There are a number of reports of potentially deadly side effects on the heart from high-energy drinks in the general population as well as people who have an underlying genetic heart condition. Plus we are seeing more frequent reports of the overall toxic effects of energy drinks. Even if you are of generally good health with no obvious health problems you should avoid energy drinks or, at the very least, limit energy drinks consumption each day.

Anyone with a family history of sudden cardiac (or unexplained) death or unexplained fainting/passing out (known as syncope), should avoid energy drinks altogether. There is a strong case against energy drinks. I’ve outlined the facts about energy drinks and the dangerous risk to your health.

Increased use of energy drinks

The energy drink market has grown rapidly in the past 10 years. Energy drinks are increasing at double the rate of all carbonated drink sales and they now outstrip the annual sales of cola.

Energy drinks are primarily targeted at teenagers and young adults but these drinks often contain more caffeine than the safe daily dose recommended for adults. Yet at present there is no regulation on the ingredients in energy drinks in Australia, Europe or the US.

Caffeine in energy drinks

Energy drinks typically contain high levels of caffeine along with a combination of other supposed energy-boosting ingredients like gurana, taurine and sugar with various other amino acids thrown into the mix.

When you add up the effects of all these ingredients, researchers have found that a single can of energy drink has nearly 500mg of caffeine. The combined levels of caffeine in these energy drinks are much higher than a standard cup of coffee (50-100mg) or a can of cola (40-60mg). It is also higher than the 400mg daily dose recommended for adults.

Dangerous health outcomes largely arise from their caffeine content. Plus energy drinks are generally downed quickly (usually in one hit), not sipped slowly like a hot cup of coffee. More recently, the energy drink formula has even been condensed to be sold as a concentrated “energy shot” in petrol stations and convenience stores.

Dangerous side effects

Caffeine is a potent stimulant, particularly at high doses. “Caffeine toxicity” can be seen even in doses less than 1g but doses of 5-10g are considered potentially lethal. At these higher doses numerous side effects can occur including increased heart rate, palpitations, increased blood pressure, improved exercise endurance, anxiety, insomnia, vomiting, nervousness and irritability.

One can of energy drink typically contains up to 500mg of caffeine. The dangerous effects of this level of caffeine is exacerbated by the common use of energy drinks that involves drinking more than one can a day or when it is combined with alcohol or physical activity.

Energy drinks and heart disorders

There are three main effects energy drinks can have on the heart: increased heart rate, increased blood pressure and evidence of increasing blood thickening that can lead to clots forming in the heart and other parts of the body. However, there have also been three recent reports that suggest energy drinks not only trigger cardiac events but can also unmask an underlying heart disorder such as long QT syndrome (LQTS) or Brugada syndrome (BrS).

These three cases are only the ones that have been published. I’ve seen a few cases myself in the past few years so I’m sure there are many more instances of this occurring in hospitals around the world.

These emerging cases highlight the potentially dangerous cardiac effects of energy drinks, not solely but particularly in those who may be at risk to deadly arrhythmias due to an underlying genetic heart disorder.

Increased awareness urgently needed

Given the potentially dangerous effects of energy drinks (especially among young people) and the mounting evidence against energy drinks, it is critical that we increase awareness in our community. This may even include more drastic measures such as clear, graphic warnings on cans like cigarette packs carry and restricting the sales of energy drinks to children and teenagers.

The ultimate goal of any of these measures should be to prevent rising levels of potentially life-threatening heart rhythm problems.


Professor Chris Semsarian

Chair, Registry Advisory Committee
Molecular Cardiologist, Royal Prince Alfred Hospital, Sydney
Professor of Medicine, University of Sydney
Program Head, Agnes Ginges Centre for Molecular Cardiology, Centenary Institute