The Truth About Energy Drinks

By Keri Peterson, MD Internal Medicine, New York, NY Women's Health Magazine

The Truth About Energy Drinks

Energy drinks are one of the fastest growing drinks in America. They promise to make you more alert, focused and invigorated. Energy drinks do achieve their goal – they can reduce sleepiness and make you feel more alert. But it may be at a cost to your health. They can cause significant side effects and there are insufficient studies to show that they are safe.

Here is a breakdown of the types of energy drinks on the market, and the most commonly used ingredients and their potential side effects.


Energy drinks come in all sorts of formulations. Bottles. Cans. Shots. Powders. You name it.  With these different formulations, what you choose to drink is really a matter of preference but here are the differences:


These are premixed and ready to drink. They can be sipped throughout the day. With this option, pay attention to serving size because many bottles can be two serving sizes or more; if you drink the whole thing, you are getting more than double the dose of the ingredients on the label.


These come in smaller pocket-sized packaging. People typically chug the whole thing all at once. The full dose hits you hard and fast and lasts 5-6 hours. It’s also less fluid volume, so it’s easier on the bladder. Some brands are reported to be gritty or medicinal tasting.


These are portable, and most require that you just add water. Like the bottled or canned varieties, they can be sipped more slowly.


Most energy drinks contain some combination of caffeine, B vitamins, sugar and herbs. 


This is the main ingredient that puts the energy in energy drinks. The concern here is the amount of caffeine that is put in energy drinks. Energy drinks can have anywhere from 80 to 500 mg per serving. Up to 200 mg of caffeine a day is considered safe.

Many of these drinks not only have very high caffeine levels, but they also combine them with other herbs that contain caffeine, such as guarana and yerba mate. Plus, keep in mind there can be multiple servings in one bottle or can, even in the small containers.

In higher doses, caffeine can have many adverse reactions. In excess, caffeine can cause insomnia, jitteriness, palpitations, rapid heart rate and elevated blood pressure. Over 200 mg of caffeine can cause blood pressure to spike by up to 14 points. Because of this, people with high blood pressure should avoid consuming energy beverages altogether. Caffeine also can cause dehydration because it has a diuretic effect. 

People can build a tolerance to caffeine as well. Over time, you may find yourself needing more doses throughout the day to achieve the same effect.

B vitamins

This group of 8 vitamins plays a variety of roles in cell metabolism. Some of these drinks have massive amounts of B vitamins. But, here’s the thing: B vitamins will not boost your energy unless you are deficient in them. Most of us get all the B vitamins we could possibly need in our diets.   

The majority of B vitamins are not toxic when consumed in excess because they are water soluble and any excess is just excreted in the urine. That is except for two of them: 

  • Too much vitamin B3 (niacin) can cause a flushing of the skin, stomach upset, blurred vision or liver inflammation. Some shots have 150% more than the maximum recommended dose of 35 mg daily.
  • Too much B6 (a dose greater than 500mg/day) can cause nerve damage, tingling and numbness in arms and legs.

As mentioned earlier, there are commonly used herbs that are often found in energy drinks.  These include:


Guaraná is a small round red fruit native to the Amazon. One guaraná seed has twice the caffeine of a coffee bean, so it imparts the increased alertness with all of the potential side effects of caffeine listed earlier. To learn more about guaraná, click here.



Extracted from the root of the ginseng plant, ginseng has been found in studies to boost brain power – but you would need at least 200 mg to reap this benefit, which most drinks don’t contain. A word of caution: Ginseng has been shown to interact with blood-thinning drugs, potentially altering their effectiveness.


One serving of an energy drink can contain as much as 14 teaspoons of sugar! That’s more than double the recommended daily dosage. This much sugar spikes our blood glucose levels which is what gives us that energy boost. When those levels drop, they come crashing down and we crash as well. Additionally, this temporary spike is not worth the weight gain that comes with excess sugar consumption. 

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