The amount of caffeine in common drinks varies widely:
- Cola (355ml): about 40mg
- Black tea (250ml): around 50mg
- Double espresso (60ml): 80mg
- Instant coffee (250ml): 100mg
- Red Bull (250ml): 80mg — about two colas or one espresso
- Monster/Relentless (500ml): 160mg — equal to four colas or two espressos
- Prime energy (330ml): 140mg — about three and a half colas or one and a half espressos
A single large energy drink can therefore contain as much caffeine as several cups of tea.
Children and Teenagers at Higher Risk
Health guidance around the world advises caution for younger people. Their smaller body size and developing nervous systems mean even one can of an energy drink may exceed recommended safe levels.
For teenagers, many health organisations suggest limiting caffeine to under 100mg a day — less than one can of Prime or Monster. For children, regular caffeine is often discouraged altogether.
Adults and Older People
For healthy adults, up to 400mg a day — the equivalent of four cups of coffee — is generally considered safe. But tolerance differs widely. Older people may find that caffeine affects sleep, heart rate, or anxiety more strongly.