Before getting to taurine and some of the other ingredients found in most energy drinks, let’s discuss the roles that caffeine, sugar and vitamins play in providing the body with fast energy.

Caffeine

Caffeine is the world’s most widely-consumed stimulant. It’s well known that the substance boosts the body’s metabolic rate while making its users feel more energetic and alert. But that only tells a small part of the story.

• Caffeine increases the effects of two neurotransmitters: dopamine, which helps to regulate mood, and serotonin, which improves focus and motivation.
• Caffeine blocks the neurotransmitter adenosine, which tells the body that it’s getting sleepy.
• Caffeine triggers the release of adrenaline which boosts heart rate, increases blood flow, and tells the liver to release sugar into the bloodstream.
• Caffeine causes muscles to contract, giving users the impression that they can perform physical tasks with less exertion than usual.

There’s much more, but the point is obvious; caffeine is a potent energy booster. How much energy does it give you, and how long does it last? We’ll get to that in a bit.

Sugar

The story about this one isn’t quite as clear-cut. It’s long been believed that sugar provides the body with the glucose it needs for energy. 

However, studies have found that sugar doesn’t really provide bountiful amounts of long-term energy.

Sugars like sucrose and high-fructose corn syrup prevent the long-term production of energy, and for the calories in sugar to be used for energy, the body has to deplete nutrients that have already been consumed.

So what causes the 30-40 minute “sugar high” we’ve all experienced? It’s because the sweet stuff also increases serotonin and dopamine levels, elevating mood rather than boosting energy.

Vitamin B

This is another complicated story.

B vitamins are commonly believed to provide energy. The body indeed needs those vitamins, but B-complex vitamins simply serve as a catalyst, used by the body to produce energy from the other foods that we eat. Vitamins aren’t the actual energy source.

One other important fact: once the body has gotten all the B vitamins it needs, it stores any additional ones in muscles or passes them in urine.

Here’s what that means. An energy drink loaded with B12 isn’t going to give you more energy. It only ensures that your body can produce the energy it’s supposed to. If you take a vitamin supplement daily, that issue has already been taken care of.

So does the Vitamin B in energy drinks help when you want a quick pick-me-up? It might, but it probably won’t.

The ingredient you often see touted as an energy drink additive is taurine. Taurine is a common amino acid that’s abundant in the body. You consume it when you eat dairy products, meat and fish, and it’s sold as a dietary supplement.

Taurine is important to central nervous system function, immune system function, and metabolic function, as well as hydration and digestion. It’s an antioxidant and anti-inflammatory that helps to regulate blood pressure and improve cardiovascular health.

But why is it in energy drinks?

Several studies claim taurine may improve athletic performance and endurance, and that when combined with caffeine, it may boost cognitive performance. Both could be perceived as boosting energy – making taurine a potentially helpful ingredient in energy drinks.

What about some of the other common additives?

• Guarana: This ingredient is derived from South American plants, and it contains high amounts of caffeine as well as other stimulants like theophylline.
• Yerba Mate: Another natural caffeine source, this South American ingredient is usually consumed in yerba mate herbal tea.
• Creatine: This is a synthetic stimulant similar to a natural amino acid, reportedly able to boost muscle mass, physical performance, focus, and memory.
• Ginseng: This Asian medicinal herb is said to boost energy, relieve stress and fatigue, and boost memory.
• Ginkgo Biloba: This common supplement is said to assist concentration and memory and help users fight depression.

Most of the claimed beneficial effects of these ingredients (except for caffeine) are shaky, and there’s so little of the additives in energy drinks that they would probably have little effect. They certainly sound impressive to many consumers, though.

What have we learned so far? Energy drinks are essentially a caffeine delivery device, with an “I think I have more energy” sugar chaser. So the real question we have to answer isn’t “how long do energy drinks last.” It’s “how long does caffeine last?”

The reason people consume energy drinks, of course, is to get more energy. So the most important effect to discuss is how long the boost will last – and that means we have to talk about caffeine.

Caffeine in Energy Drinks

Here’s the surprising fact. The amount of time that caffeine affects the body doesn’t depend on how much of it you consume. Its effects are relatively predictable, regardless of the amount of caffeine consumption.

The mean half-life of caffeine in the blood of healthy adults is about five hours, but its elimination half-life can be anywhere between 1.5 and 9.5 hours.

In simple terms, it can take nearly ten hours for some people to clear half of the caffeine they’ve consumed, but for most of them, caffeine will be effectively purged from their body about 12 hours after they’ve consumed it.

The exact time frames depend on numerous factors ranging from your overall health and weight, to whether you’re taking birth control pills. However, the energy boost you experience after caffeine intake disappears much faster than the caffeine itself.

You begin to feel the effects of caffeine about ten minutes after consuming it, and those effects peak within 30-60 minutes. That’s when you’ll receive “maximum benefit” from an energy drink.

After that first hour, physiological factors causing the energy boost begin to ease and you feel less and less of the energy drink’s effects. Within a few hours, there won’t be enough extra caffeine in your body to provide any measurable increase in energy.

So the short answer to our original question is that energy drinks last a few hours, but their most powerful effects only last an hour or two at most.

There’s one more obvious question begging to be answered: why doesn’t an energy drink last longer if it contains a high amount of caffeine?

Energy drinks do have high caffeine content. Eight ounces of black coffee contains about 95mg of caffeine, and 12-ounce caffeinated beverages (with carbonation) contain between 35 and 50mg.

By contrast, a can of Red Bull contains about 115mg of caffeine, and Monster and Rockstar contain about 160mg. Some like Rockstar Thermo, Spike and Bang contain 300mg of caffeine or even more.

But caffeine’s half-life doesn’t change. High caffeine levels in energy drinks only provide high energy levels until the effects of the caffeine start to wear off.

In other words, high levels of caffeine don’t mean you’ll have more energy for a longer time. You just have more energy during caffeine’s effective time than you’d get from a cup of coffee. No matter how much of a punch an energy drink packs, it still wears off just as fast.

Sugar in Energy Drinks

There are two reasons why the peak effects of an energy drink only last about an hour or so. One is the drop in caffeine levels we’ve mentioned. The other is that you start to experience a sugar crash.

Once you’ve had an energy drink, the body quickly produces insulin in an effort to balance the added sugar in the drink and bring blood glucose levels back to normal. The drop in blood glucose levels also causes a dramatic loss of energy, which we know as a sugar crash. That generally hits within an hour of consumption.

Serotonin and dopamine levels also fall after that first hour, meaning the mood elevation you experience from the sugar disappears as well.

That’s the reasoning behind newer energy drinks like Super Energy. They use stevia and monk fruit instead of sugar. No sugar intake means no sugar crash, so caffeine’s effects can last longer.

Sugar-free energy drinks also eliminate some of the adverse effects that Monster or Rockstar fans may suffer.

Almost any food, even the best energy drinks, can cause some side effects.

Let’s start with caffeine. The Food and Drug Administration (FDA) recommends that adults consume a maximum of 400mg of caffeine per day. Greater consumption is likely to result in jitters and insomnia at best, and high blood pressure and digestive issues for some people.

And that’s not even mentioning the difficulties of caffeine addiction and withdrawal.

Needless to say, a few cans of highly-caffeinated energy drinks can put you way over that 400mg limit. Just two cans of a product like Rockstar Thermo and you’re into the danger zone.

Then there’s sugar. The FDA recommends that most people consume no more than 50 grams of added sugar per day. That’s not a lot by modern standards.

A single energy drink contains even more sugar than soda, between 40 and 50 grams per can – meaning two Monsters or Rockstar puts you over the limit. High sugar intake can cause problems ranging from weight gain and diabetes to mood disorders and cardiovascular disease.

Finally, there are all of those extra additives in energy drinks. There are unresolved health questions surrounding ingredients like taurine, ginseng, and even excessive amounts of vitamins B3 and B6. They’re not going to poison you but they may not be particularly healthy, either.

Does that mean that energy drinks aren’t good for you? Of course not. What it does mean is that you should exercise caution and moderation when drinking anything. Coffee, soda and energy drinks can all provide benefits – as long as you know when to stop for the day.