Relentless Energy Drink Review (Is It Worth It?)

Relentless Energy Drink

Relentless energy drink is made in Ireland and is a popular choice throughout the UK.

The brand was created by The Coca-Cola Company back in 2006 and was the first to introduce larger drink sizes (500ml cans) for sale in Great Britain.

Relentless features a strong lineup of energy drinks in several attractive fruity flavours, but is it truly worth your time and money to buy a can for yourself?

In this article, I’ll share my honest opinion and review of Relentless Energy Drink.

Let’s get started…

Does Relentless Energy Drink Really Work?

I would say Relentless did work for me, but it contains a little more caffeine than I usually prefer to have in a single-serve.

But that’s just my opinion, you can give it a try and decide for yourself.

In order to see for myself whether Relentless energy drink actually works or not, I got a can to try it out for myself and drank it with my lunch.

That day, my schedule consisted of about six hours of work, followed by a gym session in the afternoon.

I thought the taste was quite refreshing, though quite sweet.

The boosting effects of Relentless were great as it helped me power through my work and I managed to maintain my concentration most of the afternoon. I even managed to survive the day without topping up with a coffee.

By the time I decided to call it a night, I genuinely felt tired as the effects of my Relentless had completely worn off. No complaints there.

My verdict?

It seemed to give me a good boost for about 90 minutes, but then I noticed my energy flagging. I guess this was a sugar-crash.

I’m surprised that the boost was OK before my energy started to dip though. Usually I don’t like my energy drinks to contain more than about 100mg per serve.

Relentless Energy Drink Review


The Relentless can has a visually pleasing design and is quite eye-catching, in my opinion.

Ingredients information provided on the product label was satisfactory.


For me, I found the taste of Relentless was very refreshing, but somewhat sweet.

The yellowish tinge of the drink can be a bit repulsive at first glance, but after I tasted it, I enjoyed the flavour.

The best part of drinking Relentless was that it did not leave any bitter aftertaste which I had experienced with some other energy drinks.

On the whole, I’d say Relentless has an enjoyable taste and is possibly quite addictive.

Ingredients And Effects

A close-up of a can of Relentless showing its ingredients and nutrition information.
Relentless energy drink actually has a pretty good list of ingredients.

Let’s evaluate the effect Relentless will have on us based on its ingredients.

A 500ml can of Relentless Origin contains: 

  • 108 calories
  • 160mg caffeine
  • 31g carbohydrates
  • 24g sugar
  • 0.70g salt
  • 16mg niacin (vitamin B3)
  • 8.5mg pantothenic acid (vitamin B5)
  • 2.0µg cobalamin (vitamin B12)
  • Carbonated water
  • Sucrose
  • Citric acid
  • Erythritol (Flavor enhancer)
  • Taurine (0.4%)
  • Sodium citrate (Acidity regulator)
  • Potassium sorbate
  • Sodium benzoate
  • Caramel E150d (Color)
  • Sucralose
  • Guarana seed extract


Relentless contains 160mg of caffeine in a 500ml can and this is an acceptable quantity for you to drink in one serving.

According to the guidelines given by the European Food Safety Authority (EFSA), you should only drink up to 200mg of caffeine per serving. Besides that, it’s also recommended that you keep to a daily caffeine intake of no more than 400mg per day.

Personally though, I prefer to only drink between 50mg to 100mg of caffeine per serving.

Much has been said about the dangers of caffeine, but in my opinion, as long as you’re taking it in moderation, I believe it can actually do a lot of good for you.

Caffeine helps to enhance your physical endurance and mental performance (alertness and ability to concentrate) during times of weariness.

Of course, you will need to be careful so that you do not exceed the 400mg daily quota. Otherwise, you may face problems like these:

  • Anxiety
  • Insomnia
  • High blood pressure
  • Muscle spasms
  • Headaches
  • Hallucinations
  • Stomach ulcers

Check out this resource for some useful tips on how to consume caffeinated drinks like Relentless more strategically in order to benefit the most from them.  


Every 500ml can of Relentless contains 24g of sugar.

Personally, I feel that having 24g of sugar within a can of Relentless is quite a lot.

It’s important to monitor not just how much sugar we consume every day, but also which sources we choose to get our sugar from. Ultimately, this is to reduce our chances of suffering from things like cardiovascular disease.

So, although drinking one can of Relentless won’t make you exceed your recommended daily intake for sugar of 30g per day, I’d still stick to one can only per day.

However, it’s worth noting that the sugar content from just one can of Relentless already takes a big portion out of your daily consumption limit.

Having said that, our bodies actually need sugar to function as this is how our cells get their energy to perform their daily tasks.

It’s just that we need to watch how we consume it (controlling your portions) and which food sources we are getting them from (foods with complex carbohydrates like grains and beans are preferred over soft drinks and candies).

If you have too much sugar in your diet, you’ll likely suffer from:

  • Diabetes
  • Low energy
  • Chronic fatigue
  • Weight gain
  • Weakened immune system
  • Premature ageing


Relentless contains 16mg of niacin (vitamin B3), 8.5mg of pantothenic acid (vitamin B5) and 2.0µg of cobalamin (vitamin B12).

These vitamins are usually included in drinks like Relentless in order to help boost your energy levels.

What’s important to remember here is that B vitamins themselves do not give you energy just because you consume them. They are useful only because they help your body in converting the food you have eaten into energy.

Here’s how the amount of B vitamins in a can of Relentless compare to your daily recommended intake:

VitaminQuantity In Relentless Energy Drink (500 ml)Daily Recommended Intake
Niacin (B3)16mg16 mg (men)
14mg (women)
Pantothenic Acid (B5) 8.5mg 5mg
Cobalamin (B12)2.0µg2.4µg
B vitamins found in Relentless energy drink vs. our daily recommended intake.

Although some doses of B vitamins included in a can of Relentless are more than what’s required for your daily needs, it’s not something you’d have to worry about.

Due to their water-soluble nature, any excess B vitamins that aren’t used up by your body will just get eliminated through your urine.


For Relentless, it was not mentioned how much taurine is actually added into the drink.

It has only been stated at 0.4%, which could possibly mean that it makes up 0.4% of the drink’s contents.

Taurine is a naturally occurring amino acid that can improve athletic performance.

According to some research studies, it can also help enhance your mental capabilities when it is taken together with caffeine.

Guarana Seed Extract

It was not indicated on the ingredients list for Relentless just how much of guarana seed extract has actually been included in this product.

Guarana is a Brazilian plant that grows berries which are naturally high in caffeine. It has a higher caffeine content than coffee beans.

For example, there’s between 1% to 2% of caffeine found in Arabica coffee beans whereas there’s 3% to 4% caffeine in guarana.

Guarana seed extract is made by grinding the berries into powder.

Guarana is a natural energiser. Among the benefits you can enjoy from it are improved concentration, better memory, reduced risk of heart disease, pain relief and much more.

Conclusion: Ingredients And Effects

The combination of ingredients we see used here show us that Relentless has something worthwhile to offer us in the form of an energy booseter.

However, as an individual, you’ll need to be aware how each of these ingredients affects you personally so you can be certain whether there is any risk to your health from taking Relentless energy drinks.

In my case, I found that the drink positively enhanced my performance without any side effects so it worked great for me.


Based on the prices I saw on, a can of Relentless costs on average around £1 and I think that’s quite reasonable.

Final Verdict

A can of Relentless energy drink.
Relentless Energy Drink is a great drink.

My take on the Relentless energy drink is that it’s a great beverage.

It is tasty, refreshing and has a certain sweetness to it that makes it very nice to drink.

It helped keep me alert throughout the day as I expected it to and I didn’t experience any nasty snapbacks from consuming it.

So as long as you drink it in moderation, I think it would be a good complement to your lifestyle. 

Here’s a review you can watch for Relentless Origin drink.

Is Relentless Energy Drink Good For Your Health?

In order to determine whether Relentless is good for your health, you’d need to look at these areas: 

  1. Assess your current health situation. 
  2. Decide what health benefits you are looking for.
  3. Compare that to what Relentless has to offer you as an energy drink. 

If you are facing any health issues at the moment, then introducing Relentless into your diet would not be a good idea. In fact, it would probably be better that you consulted a doctor first before even buying a can to try.

However, assuming you are in the green for health, Relentless might be helpful as an energy booster whenever you need something to perk you up on a tiring day.

But just like all other food and drinks, Relentless can have really bad side effects if you drink too much of it. This is mostly due to the excess caffeine and sugar that you’d have consumed.

As long as you know your limits, drinking an energy drink like Relentless should not negatively impact your health.

Alternatives to Relentless Energy Drink

Here are some other great energy drinks you can try besides Relentless: 

You can also try powdered energy drinks if you like having a more portable and versatile option: 


A sachet of REIZE next to a ready-made glass of the energy drink.
REIZE is a great alternative to Relentless energy drinks.

REIZE is a powdered energy drink and my personal favourite.

It contains only 50mg of caffeine per sachet and is sugar-free.

In addition, it has other enriching ingredients like ginseng and taurine which are also beneficial for your wellbeing.

All of these great ingredients work together to provide a great energy boost without the sugar crash.

REIZE costs only about $1 per sachet and you can enjoy free shipping when you order it online.

Give it a try and see. You just might end up liking it more than Relentless.

Last Updated on

Marty Spargo

I started my own energy drink brand in 2014 and am passionate about educating people about energy drinks so that they can properly understand the ingredients, benefits and risks without being influenced by the marketing messages put out by some brands. You can read my full bio here.

Recent Content