Most electrolyte advice tells you what to take and skips when. This guide covers the timing: before, during and after exercise, plus illness, hot work and travel. Figures come from the 2007 American College of Sports Medicine (ACSM) position stand on exercise and fluid replacement and the 2016 joint position paper on nutrition and athletic performance.
If you want to know what electrolytes are and what a deficiency looks like, start with our electrolytes explained guide. This page picks up from there.
Quick Answer: When to Take Electrolytes
Take electrolytes when you are losing a lot of sodium: long or hot sessions, heavy sweating, vomiting or diarrhoea. For a normal day or a workout under an hour, water and food cover you. Spread fluid and sodium across the hours around exercise rather than rushing a drink into a fixed window.
Everyday Hydration vs Strategic Electrolytes
On a normal day, food supplies your sodium, potassium and magnesium, and thirst tells you when to drink. An electrolyte mix is a tool for specific situations, not a daily requirement. Replacing sweat with large volumes of plain water can lower blood sodium, which is why the Third International Exercise-Associated Hyponatremia Consensus Statement (2015) concluded that drinking to thirst is enough to prevent both dehydration and hyponatremia.
Before Exercise
The goal is to start euhydrated, not to overload. The ACSM advises slowly drinking about 5 to 7 mL of fluid per kg of body weight at least 4 hours before exercise. For a 70 kg person that is roughly 350 to 490 mL. If your urine is dark, drink another 3 to 5 mL per kg (about 210 to 350 mL) around 2 hours before.
The ACSM also notes that sodium in the drink, or small amounts of salty snacks and sodium-rich food at meals, helps you retain the fluid and stimulates thirst. For most people a normal salted meal does this job. A sodium drink earns its place before a long session in heat, when you expect to sweat heavily.
During Exercise
For sessions under about an hour, water and drinking to thirst are enough. The aim is to avoid losing more than about 2% of body weight, and equally not to overdrink.
For longer sessions or heavy sweat, the ACSM suggests sodium at about 0.5 to 0.7 g per litre of fluid, and the 2016 position paper suggests 30 to 60 g of carbohydrate per hour. Sip steadily rather than gulping. Heavy sweaters, salty-sweaters (white marks on clothes) and people training in the heat lose more sodium and need more attention to this.
After Exercise
There is no 30-minute window that closes. The 2016 position paper advises drinking 125% to 150% of the fluid you lost, and including sodium, because plain water replaced alone is partly lost as urine. A simple way to track it: weigh yourself before and after. Each kilogram lost is about a litre of fluid, so aim for roughly 1.25 to 1.5 litres per kg over the next few hours.
Food counts. A salted meal with a drink restores sodium and fluid together. If you will train again within 12 hours, start replacing sooner.
Other Times Electrolytes Help
- Vomiting or diarrhoea. Use an oral rehydration solution mixed as directed. Sports drinks and electrolyte mixes are not designed for this. The reasons are in the oral rehydration section of our main guide.
- Hot, physical work. The NIOSH guidance on hydration in the heat is about 1 cup (8 oz) of water every 15 to 20 minutes, and no more than 48 oz an hour, because drinking too much can dilute blood sodium.
- Flights. Cabin air is dry, but the UK Civil Aviation Authority physiology of flight guidance says it does not cause dehydration. Extra fluid loss is about 150 mL over 8 hours. Drink to thirst. If your mouth and lips feel dry, that is the dry air, not a mineral shortage.
- Low-carbohydrate diets. Some people report headaches and fatigue in the first days of cutting carbohydrates, and extra sodium is commonly suggested. Trial evidence is limited and there is no standard dose, so keep it modest and check with a doctor first if you take blood pressure medicine.
Sugar or No Sugar?
Sugar matters for fuel, not for hydration. For exercise longer than an hour, the 30 to 60 g per hour of carbohydrate in the position paper comes from drinks, gels or food, and a zero-sugar mix does not supply it. For short workouts, desk days and heat without long exercise, a zero-sugar drink is fine.
Using Func Lab Salty Hydration Mix
Each 5.6 g sachet of Salty Hydration Mix has 1,000 mg sodium, 210 mg potassium and 70 mg magnesium (as magnesium gluconate), with 0 g sugar and 2 g carbohydrate. The label directs one sachet in 400 to 600 ml of water.
That works out to roughly 1.7 to 2.5 g of sodium per litre, well above the 0.5 to 0.7 g per litre the ACSM suggests for sipping during exercise. So it suits the before and after moments, or a heavy-sweat day alongside plain water, better than being your only drink mid-session. For a long session, carry plain water too and follow the label directions.
Women who track their cycle may also like our electrolytes for women guide. For coconut water as a lighter option, see coconut water vs sports drinks, and for the morning habit our lemon water guide. If you feel thirsty all day even though you drink plenty, read feeling dehydrated while drinking 3 litres a day.
If you are pregnant, have kidney, heart or blood pressure problems, or take medicine, ask your doctor before using electrolyte supplements.
Warning Signs
- Mild. Thirst, dark urine, headache and tiredness. Drink fluids with some sodium, rest and cool down. For symptoms by mineral and when to get tested, see our electrolyte deficiency symptoms guide.
- Overdrinking. Nausea, headache, bloating, confusion or swelling in the hands and feet after drinking a lot of fluid can point to low blood sodium. Stop drinking and get medical help if confusion, vomiting or seizures appear.
- Heat illness. Confusion, fainting, a racing heart, hot dry skin or no sweating after exertion in heat needs urgent medical care.
- Rhabdomyolysis. The CDC NIOSH rhabdomyolysis signs and symptoms page lists severe muscle pain, weakness and dark, tea- or cola-coloured urine, and notes that all three together are uncommon. See a doctor the same day if you have dark urine with muscle pain or swelling.
Frequently Asked Questions
When is the best time to take electrolytes?
It depends on the situation. Before a long or hot session, a drink with sodium alongside your normal fluids helps you start well hydrated. During sessions longer than about an hour, or in heavy sweat, sip a drink with sodium and carbohydrate. After a long session, replace fluid with sodium and a meal. For a normal day or a workout under an hour, plain water and food are usually enough.
Should I take electrolytes before a workout?
Only if you will sweat heavily or train for a long time. The ACSM advises drinking about 5 to 7 mL of fluid per kg of body weight at least 4 hours before exercise, and sodium in the drink or a salty snack helps you hold on to that fluid. For a short session, drink to thirst.
Is there a 30-minute recovery window for electrolytes?
No. The research supports replacing fluid and sodium over the hours after exercise, not within a fixed window. The 2016 joint position paper advises drinking 125% to 150% of the fluid lost, and eating a normal meal with salt helps. If you train again within 12 hours, start sooner.
Do electrolytes stop muscle cramps?
Not reliably. The 2016 position paper says the cause of exercise-associated muscle cramps is unclear, and muscle fatigue is a leading suspect. Sodium can still help if you have lost a lot in sweat, but it is not a proven cramp cure.
Should electrolyte drinks contain sugar?
Only for long sessions. The position paper suggests 30 to 60 g of carbohydrate per hour for exercise lasting more than an hour, and a zero-sugar mix does not provide that. For shorter sessions, daily use and illness-free days, no sugar is needed.
Do I need electrolytes on a flight?
Not because of cabin air. The UK Civil Aviation Authority says low cabin humidity does not cause dehydration, and the extra fluid loss is only about 150 mL over 8 hours. Drink to thirst, and use a sodium drink only if you are also sweating, vomiting or have diarrhoea.
The Bottom Line
Electrolytes are for specific moments: long or hot sessions, heavy sweat and illness. Start hydrated using the ACSM pre-exercise guide, sip with sodium during long sessions, and replace 125% to 150% of fluid lost over the hours afterwards with food. For everything else, water and a normal diet are enough.
This article is for general information and is not medical advice.
