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You’ve probably stood in the supplement aisle staring at a wall of powders, tablets, and pre-mixed bottles, all promising to stop your legs from cramping at mile 18. Some cost £1.50 a serving. Others cost 30p. Most taste like slightly sweet chalk. And almost none of them tell you what actually matters: how much sodium is in there, and whether you even need it for the run you’re doing.
This isn’t a “top 10 amazing products” list. It’s a comparison based on what electrolyte drinks are actually for, what’s in the ones you’ll find on UK shelves, and where your money is genuinely worth spending versus where you’re paying for marketing.
If you’re running under an hour, in mild weather, chances are you don’t need any of this — water’s fine. If you’re training for a marathon through a hot summer or you’re a heavy, salty sweater (check your kit for white streaks after a long run), this is worth reading properly.
What electrolyte drinks are actually replacing
When you sweat, you lose water and sodium — the sodium loss is the part most runners underestimate. Sodium helps your body retain fluid and keeps your nerves and muscles firing properly. Lose too much without replacing it, and you get the classic symptoms: cramping, nausea, that heavy, foggy feeling in the final third of a long run. The NHS notes that sodium needs vary hugely between individuals — some runners lose over 1,500mg of sodium per litre of sweat, others under 400mg. There’s no universal number, which is exactly why generic advice (“just drink an electrolyte drink”) often misses the point.
Potassium, magnesium and calcium get mentioned on packaging too, but the amounts in most sports drinks are small enough that food covers your needs better than any powder will. Sodium is the one doing the real work here.
The main types you’ll find in the UK
Electrolyte products broadly fall into four categories, and they’re not interchangeable.
| Type | Examples | Sodium per serving | Best for |
|---|---|---|---|
| Isotonic sports drinks | Lucozade Sport, High5 Energy Source | 200–350mg | Runs 60–90 min, combines carbs + electrolytes |
| Electrolyte tablets | Nuun, SIS Hydro | 300–400mg | Hot weather, long runs, low-calorie option |
| Electrolyte powders/mixes | Precision Hydration, Tailwind | 150–1500mg (varies by product) | Customisable to your sweat rate |
| Homemade | Water + salt + squash | Fully adjustable | Budget option, race-day tested |
Precision Hydration is worth calling out separately because it’s built around individual variation rather than a one-size-fits-all formula — they sell products ranging from 250mg to 1500mg of sodium per serving, aimed at people who’ve actually tested their sweat rate rather than guessed.
Head-to-head: what you’re actually paying for
Here’s how the popular options stack up on the things that matter — sodium content, taste, cost, and whether they include carbs (which matters if you’re also fuelling, not just hydrating).
| Product | Sodium/serving | Carbs? | Cost per serving (approx) | Honest verdict |
|---|---|---|---|---|
| Nuun Sport | 300mg | No (minimal) | £0.50 | Light, easy to drink daily, low calorie — good for shorter runs or everyday hydration |
| High5 Zero | 100mg | No | £0.35 | Cheap and pleasant but sodium is low for serious heat or long efforts |
| SIS Hydro | 500mg | No | £0.60 | Strong sodium hit, useful for hot marathons, some find it salty |
| Precision Hydration 1000 | 1000mg | No | £1.20 | Designed for heavy sweaters — expensive but purpose-built |
| Tailwind Endurance | 310mg | Yes (~50g carbs) | £1.50 | Doubles as fuel and hydration — useful for long runs, can feel heavy on the stomach for some |
| Lucozade Sport | 220mg | Yes (~30g carbs) | £1.00 (500ml) | Widely available, decent for race day if your stomach already tolerates it |
| DIY (water + ¼ tsp salt + squash) | ~500mg (adjustable) | Optional | £0.05 | Cheapest by far, fully customisable, but needs testing before race day |
A few honest notes from that table. High5 Zero and similar “zero calorie” tablets are pleasant to drink but often too weak in sodium to do much for a hot, sweaty long run — they’re closer to flavoured water. Tailwind and other carb-electrolyte combos are genuinely useful for long runs because they simplify your fuelling — one bottle instead of gels plus water — but they’re not for everyone’s gut, and if you already have a gel strategy that works, as covered in our energy gels comparison, there’s no need to switch just because a drink promises to do more.
The DIY option gets dismissed too quickly. A pinch of table salt (roughly ¼ teaspoon per 500ml) plus a splash of squash for taste gives you a genuinely usable homemade electrolyte drink for a fraction of the price. Runners have used versions of this for decades before sports nutrition became a retail category.
When you actually need one
This is the part most product comparisons skip. For runs under 60 minutes in normal UK weather, plain water is enough — your body isn’t losing enough sodium to justify it, and Runner’s World’s hydration guidance backs this up consistently. Electrolyte drinks earn their place when:
- You’re running longer than 90 minutes, especially in heat above 20°C
- You’re marathon training and doing back-to-back long runs, similar to the demands in a 16-week marathon plan
- You know you’re a heavy sweater (salt stains on your cap or vest are a decent clue)
- You’re prone to cramping in the final third of long runs despite otherwise solid training
If none of those apply to you, save your money. Buying an electrolyte drink because it’s what elite marathoners use, when you’re running 5K three times a week, is spending money to solve a problem you don’t have.
Taste and gut tolerance matter more than the label
The best electrolyte drink on paper is useless if you can’t stomach it mid-run. Sodium-heavy formulas like Precision Hydration’s stronger mixes can taste noticeably salty — some runners get used to it, others gag. Carb-electrolyte combos like Tailwind and Lucozade Sport can cause bloating in runners who haven’t practiced with them, which ties into the same gut health principles that apply to gels and race-day nutrition generally: nothing new on race day, always test in training.
Practically, that means trying any electrolyte drink on a long training run at least three times before you rely on it for a race. What works at a 12°C training run in March might feel very different at 22°C on marathon day in September.
Building your own strategy without overspending
You don’t need to buy every product in the comparison table to figure out what works. A sensible approach:
- Start with plain water for anything under an hour.
- For long runs over 90 minutes, try one mid-range option (Nuun or SIS Hydro) and see how you feel afterward — any cramping, headaches, or that “swollen fingers” feeling by the end.
- If you’re still struggling, consider a sweat test or a stronger sodium product like Precision Hydration, but only after ruling out simpler fixes like pacing too hard for the heat or under-fuelling earlier in the run.
- Save the pricier combined carb-electrolyte drinks (Tailwind) for genuinely long efforts where simplifying your fuelling is worth the extra cost.
This mirrors the same trial-and-error most runners already do with pacing and gear — the carbohydrate loading guide makes a similar point about testing fuelling strategies well before race day rather than guessing on the start line.
The Honest Takeaway
- For runs under an hour in normal weather, plain water beats any electrolyte drink — save your money.
- Sodium content is the number that matters most; check the label, not the marketing claims about “electrolyte blends.”
- A homemade mix (water, a pinch of salt, a splash of squash) works nearly as well as premium products for most runners, at a fraction of the cost.
- If you’re a heavy sweater or marathon training through summer heat, a higher-sodium product like SIS Hydro or Precision Hydration is worth the extra spend — but test it in training first.
- Never try a new electrolyte drink for the first time on race day. Your gut doesn’t care how good the science looks on the label.
Next read: How to spot dehydration before it wrecks your run