Gym-goers keeping track of caffeine
If you also have coffee, tea or a pre-workout product, the caffeine stated for the whole can helps you work out what else is already part of your day.
Who is this choice for?
A sparkling energy drink is worth assessing against your snack, other caffeine and plans for water during training—not just its flavour or can size.
Snack buyers who want a zero-sugar drink
You may prefer to keep sugar out of the drink while choosing food separately. Monster lists 0 g sugar but 150 mg caffeine for a 500 ml can of Ultra Fiesta, so check both figures.
Occasional buyers who prefer a smaller can
A 250 ml can may be easier to fit into your plans than a 500 ml one. Red Bull states that its Original 250 ml can has 80 mg caffeine and 27 g sugars: smaller does not mean sugar-free.
What should you check before choosing?
Start with the figures for the exact can you intend to drink, then consider your snack and how you will replace fluids during training.
| Priority | What to check | Your needs |
|---|---|---|
| Caffeine | Read the caffeine amount in mg for the full can, not just per 100 ml. Count caffeine from other drinks and pre-workout products too. Red Bull states 80 mg per 250 ml Original can; Monster lists 150 mg per 500 ml Ultra Fiesta can. | I want to know how much caffeine this particular can adds to what I have already consumed today. |
| Sugar | Compare sugar in g for the full can and check the exact variant. Red Bull states 27 g sugars for Original 250 ml, while Monster lists 0 g for Ultra Fiesta 500 ml and 55 g for Original 500 ml. | If my snack already contains the food I want, I may prefer a zero-sugar drink. If I am considering a sugared can, I want to know what the whole can contains. |
| Fluids | Plan water separately, especially when you expect to sweat. The NHS advises water for replacing fluids lost through physical activity; a sparkling format does not change that guidance. | I like a fizzy drink, but I also need a way to replace fluids during training. |
| Warnings | Read the warning on the exact pack. The NHS says not to exceed 200 mg caffeine a day during pregnancy; Relentless advises that White Citrus is not recommended for children, people sensitive to caffeine, pregnant women or women who are nursing. | Before buying a high-caffeine drink, I want to check whether its warnings apply to me. |
Common buying mistakes
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Reading “zero sugar” as “low caffeine”
Monster lists 0 g sugar and 150 mg caffeine in the same 500 ml can of Ultra Fiesta. One figure cannot stand in for the other.
Check both amounts for the full container, then include caffeine from coffee, tea and any pre-workout product in your decision.
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Using an energy drink as the hydration plan
A preference for carbonation does not make an energy drink the drink to rely on for replacing fluids lost through activity. The NHS advises water for that purpose.
Bring water for training and consider any energy drink as a separate caffeinated drink.
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Assuming every can from one brand has the same nutrition
Monster lists 160 mg caffeine and 55 g sugar for a 500 ml Original can, compared with 150 mg caffeine and 0 g sugar for a 500 ml Ultra Fiesta can.
Read the flavour, variant and pack size on the can you are buying rather than carrying figures across the range.
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Overlooking caffeine warnings
Pregnancy and caffeine sensitivity can change whether a high-caffeine can is appropriate. The NHS gives a 200 mg daily caffeine limit during pregnancy, and Relentless advises against White Citrus for several groups, including children and people sensitive to caffeine.
Read the specific pack warning and consider caffeine from all sources. If you need advice about your circumstances, ask an appropriate healthcare professional.
Brand and retailer references
Ranges differ by variant, so these references are starting points for checking a particular can, not substitutes for its label.
Red Bull
Red Bull’s Original provides an example of a 250 ml energy-drink can with stated full-can caffeine and sugar amounts.
- Red Bull states 80 mg caffeine per 250 ml Original can.
- The same can contains 27 g sugars according to Red Bull; check the chosen pack when comparing variants.
Monster
Monster’s UK product information covers both a zero-sugar carbonated Ultra Fiesta can and a sugared Original can in 500 ml sizes.
- Monster lists 0 g sugar and 150 mg caffeine for Ultra Fiesta 500 ml.
- Monster Original 500 ml lists different amounts—55 g sugar and 160 mg caffeine—so check the variant.
Relentless
Relentless describes White Citrus as a carbonated citrus-flavour energy drink containing caffeine.
- White Citrus is identified by Relentless as a sparkling option.
- Relentless advises that White Citrus is not recommended for children, caffeine-sensitive people, pregnant women or women who are nursing. Check the exact can for its caffeine and sugar amounts.
Lucozade
Lucozade describes its Alert range as sparkling, high-caffeine soft drinks.
- The Alert range offers another sparkling format to consider.
- Check the chosen flavour and pack for its full-can caffeine and sugar amounts before comparing it with other drinks.
Tesco
Tesco is a retailer, not an energy-drink formulation. Tesco Groceries lists products from brands including Red Bull, Monster and Relentless.
- Its category listings can help identify pack sizes and variants to compare.
- A category listing does not establish that a particular drink suits your pre-workout plans or is available at your location.
Joybuy options for a pre-workout snack
These sparkling drinks include smaller cans, zero-sugar variants and larger caffeine servings. Compare the exact can and pack details with your snack and other caffeine intake; the products are not a ranking of pre-workout suitability.
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Applied Nutrition ABE White Natural, 12 × 330 ml
A carbonated drink described for use before exercise; the product directions say to consume a 330 ml can 15–30 minutes beforehand. The listing states 200 mg caffeine and 0 g sugar per can. Account for other caffeine, and read its cautions concerning age, pregnancy, breastfeeding, caffeine intolerance, medicines and supplements.
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Monster Ultra White, 12 × 500 ml
A carbonated zero-sugar option if you want the sugar kept out of the drink. The listing states 160 mg caffeine and 0 g sugar per 500 ml can. Count other caffeine you consume and check the pack warnings, including those concerning children, pregnancy, breastfeeding and caffeine sensitivity.
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Red Bull Energy Drink, 12 × 250 ml
Each carbonated 250 ml can is listed with 80 mg caffeine, giving you a smaller can to compare with the 500 ml options. Check the sugar amount on your pack before relying on a full-can figure, and read the listed cautions concerning children, pregnancy and breastfeeding.
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Rockstar Blueberry & Pomegranate, 12 × 500 ml
A carbonated 500 ml option with a stated 200 mg caffeine per can. Check the pack for sugar in the full can before comparing it with other variants; the listing gives sugar per 100 ml. Include other caffeine in your plans and read the cautions concerning children, pregnancy, breastfeeding and caffeine sensitivity.
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Red Bull Sugarfree Energy Drink, 4 × 250 ml
A smaller carbonated can for shoppers who want a zero-sugar drink; the listing states 0 g sugars and gives caffeine as 32 mg per 100 ml. Check the caffeine amount for the full 250 ml can on the pack when planning your intake, and read its cautions concerning children, pregnancy, breastfeeding and caffeine sensitivity.
Frequently asked questions
Is a smaller can always the better choice before training?
No: compare caffeine and sugar for the full can against what you want with your snack. Red Bull states that Original 250 ml contains 80 mg caffeine and 27 g sugars, whereas Monster lists 150 mg caffeine and 0 g sugar for Ultra Fiesta 500 ml. The smaller option contains less caffeine in these two examples, but it is not sugar-free.
Can a sparkling energy drink replace water during exercise?
Do not rely on it as your way to replace fluids lost through activity. The NHS advises water for that purpose, so plan water separately if you choose a caffeinated drink.
Is there one caffeine amount to aim for before exercise?
No single amount suits everyone, and a safety assessment is not an exercise target. The European Food Safety Authority states that single doses up to 200 mg and daily intakes up to 400 mg from all sources do not raise safety concerns for the general healthy adult population. Consider individual sensitivity and all the caffeine you consume; different guidance applies during pregnancy.
What should I check if I am pregnant?
Check caffeine from every source against NHS guidance not to have more than 200 mg a day during pregnancy. Also read the exact product warning: Relentless says White Citrus is not recommended for pregnant women or women who are nursing.
Has England announced an age restriction for high-caffeine energy drinks?
Yes. In July 2026, the UK Government announced that sales of high-caffeine energy drinks to under-16s in England would be banned from April 2027. That announcement concerns England and a future start date; it does not establish an identical rule for the rest of the UK.