Relentless Energy Drink Ingredients (Facts And Figures)

What does that can of Relentless that you’ve been drinking actually contain? Here’s a quick look at the ingredients in Relentless energy drink and the effect they might have on your health.

At the same time, I’ll also be giving you a quick rundown of how Relentless stacks up against some of its competitors. 

Well, let’s get to it then.

Where Is Relentless Energy Drink From?

Relentless energy drinks are manufactured in Ireland. The product is owned by the Coca-Cola Company. It has been in the market since 2006 and is popular both in the UK as well as the US.

Where Can I Buy Relentless Energy Drink From And How Much Does It Cost? 

If you’re living in the UK, you should be able to find Relentless energy drinks at most shops within your community. 

But there’s always the option of buying it online if you’re located elsewhere. You can try sites like Amazon or eBay. However, you may need some time to compare prices and shipping costs to ensure you’re getting the cheapest possible price.

As for the average price for a can of Relentless energy drink, it should be around £1 per can.

This is not inclusive of shipping costs.

What Flavours Does Relentless Have To Offer? 

Relentless comes in seven flavours. They are: 

  • Origin
  • Zero (sugar-free version)
  • Mango
  • Lemon Ice
  • Cherry
  • Passion Punch
  • Apple Kiwi

Other than Relentless Origin and Relentless Zero, most of the other flavours of Relentless are fruity in nature. So if this kind of taste appeals to you, then you might enjoy trying the full range of flavours that the brand has to offer.

An image of the Relentless energy drink ingredients list as seen on the side of the can.
Ingredients for Relentless energy drinks are clearly indicated on the can.

Relentless Energy Drink Ingredients

In a 500ml can of Relentless Origin, you will find these ingredients:

  • 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)

Relentless also contains trace amounts of:

  • 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

Most of these ingredients are pretty common in energy drinks and there isn’t really anything unusual in this list. In fact, everything is very clearly spelled out here, including the quantities used for the main ingredients. 

Is The Amount Of Caffeine In Relentless Energy Drink Safe?

A picture of coffee beans.
Limit your caffeine consumption to a maximum of 400mg per day.

Relentless has 160mg of caffeine in each 500ml can and yes, it is safe to drink it as long as your total caffeine consumption for the entire day does not go over 400mg. 

This figure is based on the recommendations of the European Food Safety Authority (EFSA) which states that you should limit yourself to a maximum of 400mg caffeine per day. It also suggests you take only up to 200mg of caffeine in each serving. 

My personal practice is to actually limit caffeine consumption to around 50mg to 100mg per serving.

With these things in mind, it’s obvious that the caffeine levels in Relentless are safe for you to consume, but you need to remember to take stock of how much caffeine you are consuming from other sources too.

You should also always keep a lookout for any symptoms of caffeine overdose

In addition, all of these guidelines assume that you are a normal, healthy adult. 

The situation would be different if you have any health problems. If you do, then it would be wise to consult a doctor before deciding to take energy drinks like Relentless. 

The reason that we don’t want to end up taking too much caffeine is to avoid health problems such as these:

  • Anxiety
  • Irritability
  • Drowsiness
  • Heart Burn
  • Insomnia
  • High blood pressure
  • Caffeine addiction
  • Rapid heart rate
  • Fatigue
  • Loss of bladder control
  • Muscle breakdown
  • Digestive issues

Is The Amount Of Sugar In Relentless Energy Drink Safe?

A 500ml can of Relentless contains 24g of sugar, and it is safe to consume this as long as your total intake of free sugars in a day does not exceed 30g.

The National Health Service (NHS) tells us that adults should have no more than 30g of free sugars in a day. 

What is meant by “free sugar” here is the sugar that you find in the food and drinks that you are eating every day. This also includes things like honey, syrups as well as unsweetened fruit and vegetable juices.

So you’ve actually got to monitor all the sources of sugar you’re consuming on a daily basis in order to decide whether or not what you find in a can of Relentless is safe for you.

With this in mind, it’s best to only drink one can of Relentless in a day. Or you could go for Relentless Zero (the sugar-free version) if you want to take more than one can. 

Whatever your decision might be, I would suggest that you don’t go beyond 30g quota suggested by the NHS so that you won’t be exposed to these health issues:

  • Weight gain
  • Heart disease
  • Acne
  • Type 2 diabetes
  • Cancer
  • Depression
  • Skin ageing
  • Fatigue
  • Fatty liver
  • Kidney disease
  • Gout
  • Dental cavities
A can of Relentless energy drink resting on rattan furniture.
A can of Relentless contains 24g of sugar.

Relentless Vs Red Bull


A can of Red Bull contains 80mg of caffeine whereas Relentless has 160mg of caffeine in a can.

Both brands contain levels of caffeine that are well within the range recommended by EFSA (200mg of caffeine per serving and a maximum of 400mg of caffeine in a day). 

Of the two options, however, Red Bull has the lower caffeine content.


For sugar, Relentless has 24g in a can whereas Red Bull has 27g in it. 

While both remain within NHS guidelines for a 30g limit of free sugars daily, Red Bull has the higher sugar content between the two. 

So if minimising sugar intake is your aim, then you would want to choose Relentless over Red Bull.


On, I found Relentless being sold at £1.66 per can whereas Red Bull was priced at £1.89 each. These prices are excluding shipping costs. 

Assuming shipping costs was not a concern, then Relentless would be the cheaper option.

Relentless Vs Monster


While Relentless has 160mg of caffeine per can, Monster has 179mg of caffeine instead. 

You’d still be staying within the EFSA’s recommendation of 200mg per serving when you consume either brand.


As for sugar content, Relentless has 24g of sugar whereas Monster has 54g of sugar.

This equates to 4.8g sugar in every 100ml of Relentless and 11.4g sugar for every 100ml of Monster.

You could therefore say that Monster has more than double the amount of sugar you’d find in Relentless.

So if you’re aiming to curb your sugar intake, Relentless would be the better choice for you. 

However, both brands also have sugar-free options (Relentless Zero and Monster Absolutely Zero), and you can consider them if it suits your dietary needs better.


Based on what I saw on, you would be able to buy a can of Monster energy drink for around £1.70 and for a can of Relentless, it would be about £1.66.

In terms of price, Relentless energy drink is the cheaper option.

Relentless Vs REIZE


In order to make a comparison between Relentless and Reize, we’ll need to go by the assumption that you’ll be mixing 250ml of liquid to 1 sachet of REIZE energy powder.

With this in mind, we can see that Relentless offers 160mg of caffeine per 500ml and Reize gives you 50mg of caffeine in 250ml. 

If a stronger energy drink is what you’re after, then go for Relentless. Otherwise, REIZE would be the better choice to keep your caffeine consumption in a sensible range.


For sugar content, Relentless has 24g of sugar in a 500ml can for all of its flavours except for Relentless Zero, which is sugar free. 

As for REIZE, it’s entirely sugar-free.

So, on the basis of sugar content, either brand would be fine since both have a sugarless option available for you. 


Relentless retails for about $1.29 per can excluding shipping, while REIZE is only around $1 inclusive of shipping right to your door.


Overall, I would give Relentless a 7/10 rating. It tastes good and given its 500ml volume, I felt it offered great value for money.

It’s also great to have seven flavours to choose from, and I am especially happy that there is a fruity twist to them. 

However, I would have preferred the caffeine content in each can to be a little less so that it could cater to those who have low caffeine tolerance yet are keen to give the drink a try.

Watch this video for an overview of how these three brands compare to each other.

Alternatives to Relentless Energy Drink

In addition to the brands we already discussed above, you may also want to try:

Or if you like powdered energy drinks more, then you could check out these brands:


A sachet of Reize energy drink powder next to ready-made glass of the drink.
REIZE is a compact and versatile powdered energy drink option.

Besides being sugar-free and containing a reasonable amount of caffeine, REIZE also contains a host of energy-boosting ingredients such as taurine, ginseng and B vitamins. 

This powdered energy drink comes in compact sachets, making it a really versatile option since you can easily carry it around with you and mix it with any beverage of your own choosing. 

While it is generally recommended that you mix one sachet of REIZE energy powder to 250ml of water, you can always adjust the volume of water you use to make your drink as diluted or concentrated as you like.

Besides that, REIZE only costs about $1 per sachet and this includes shipping costs.

Give REIZE a go and experience how good it is for yourself. 

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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.

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