Relentless Energy Drink

Caffeine Levels

per fl. oz can


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Relentless is manufactured by the Coca-Cola Company and was released in 2006 in the UK. It then made its way to Germany, Australia and New Zealand and recently has been spotted in the USA as well.

Recently Monster Energy acquired rights to the brand in a stock deal made with Coca-Cola

A can from the USA listed a caffeine content of 197mg of caffeine.

The brand was inspired by "action sport and modern punk rock" and comes with the tag-lines "no half measures" and "your energy your obsession".

Relentless Energy Drink comes in several varieties:

  • Original: Reviewed below
  • Immortus: Tropical juiced 
  • Libertus: Sugar-free (currently being phased out)
  • Devotion: Berry juiced (currently being phased out)
  • Orange Crush
  • Cherry
  • Origin Ultra (zero-calorie)
  • Apple & Kiwi
  • Lemon Ice

Independent Review


The first sip reminded me of a traditional energy drink, but it had something extra, something I can't put my finger on. I find myself wanting to say citrus Red Bull, but it felt like it had a lot more depth than that.

Relentless is incredibly unique and I am just thanking the energy drink gods for not making this another RB clone. We really do not need another one of those.


Relentless Energy Drink, with its 197 milligrams of caffeine, does provide a worthwhile kick. However, its lack of some other energy ingredients fail to make the effects last as long as some of the other energy drinks. I suppose it comes down to what mood you are in.

Do you want sustained energy? Look elsewhere. Do you want a quick jolt? Grab a Relentless Energy Drink. Relentless is without a doubt a quality energy drink.

If you see one on the shelf at your local Big Lots, don't hesitate to pick it up. The price tag may read 70 cents, but trust me when I say it is worth a heck of a lot more than that.

Reviewed by Avery Hage

Ingredients in Relentless Energy Drink

Sugar content: 50.5 grams (per 16.9 ounces).

Compare Sugar Content

Caffeine Concentration

Relentless Energy Drink contains 9.47 mgs of caffeine per fluid ounce (32.01mg/100 ml).

Caffeine (mg) per Ounce
100 90 80 70 60 50 40 30 20 10 0 Relentless Energy Drink 5 Hour Energy Coffee (Espresso) Coca-Cola Classic Spike Energy Drink