Energy drinks aren't one product with different labels on it, the caffeine content varies enough between brands that comparing them by the can, rather than the brand name, actually matters.
Caffeine content compared
- Red Bull — 80mg per 250ml can (32mg per 100ml).
- Monster Energy — around 160mg per 500ml can (32mg per 100ml).
- Relentless — around 160mg per 500ml can (32mg per 100ml).
- Prime Energy — around 200mg per 355ml can, noticeably higher per 100ml than the others on this list.
The per-100ml figure is the fairer comparison, since can sizes vary, but Prime Energy is genuinely more concentrated, not just sold in a smaller can.
Who they're actually aimed at
The category's marketing has shifted noticeably over the decades. Red Bull built the market through motorsport and extreme sports sponsorship, positioning energy drinks as a performance product. Monster moved the same idea into gaming and esports sponsorship. The newest wave, Prime being the clearest example, is marketed directly through social media personalities to a younger audience that was never the target market for the original motorsport-branded drinks.
The UK rules around who can buy them
There's no single UK law banning energy drink sales to under-16s outright, but most major supermarkets, including the largest chains, introduced their own voluntary age restrictions on high-caffeine energy drinks some years ago, refusing sale to anyone who appears under 16. It's a retailer policy rather than a legal requirement, which is why enforcement varies between shops. Our Prime range covers the hydration and energy side of what we stock.
Frequently asked questions
Which mainstream energy drink has the most caffeine per can?
Prime Energy, at roughly 200mg per 355ml can, noticeably higher per 100ml than Red Bull or Monster.
Can under-16s buy energy drinks in the UK?
No national law bans it, but most major supermarkets voluntarily refuse sale to under-16s.
Who are energy drinks actually marketed to?
Originally motorsport and extreme sports fans; now heavily aimed at gamers, students and young social media audiences.