Short answer: Our pick after the sauna is Fire Salt Essential Hydration: 670 mg sodium, 90 mg magnesium and coconut water in one zero-sugar stick, mixed cold in 16 to 32 oz of water. A typical 15 to 20 minute dry sauna session costs about half a liter of sweat, and sweat is mostly water and salt. Long rounds, sauna after a workout, or a daily habit is exactly when a stick pays off. If you want maximum sodium, LMNT has 1,000 mg.
Fire Salt publishes this guide, and we rank our own stick first. Specs and prices come from each brand's own website as of October 8, 2026.
How much do you sweat in a sauna?
More than it feels like. In a study of young adults in a 90°C dry sauna (two 10-minute rounds with a short break), body mass loss ranged from about 0.24 kg in lighter women to 0.82 kg in heavier men (Podstawski et al., 2014). The same paper notes sweating peaks around 15 minutes in, with about 0.5 kg lost on average per session. Other research puts sauna sweat rates at about 0.5 to 1.0 kg an hour.
One kilogram of body mass lost is roughly one liter of fluid. So a typical session is about 0.25 to 0.8 liters gone. Bigger people and longer sessions lose more.
What do you lose besides water?
Mostly sodium and chloride. That's what makes sweat salty. Sweat also carries smaller amounts of potassium, calcium and magnesium. A Japanese study of sweat collected during 30 minutes of sauna bathing measured all of these (Hoshi et al., 2001, Tohoku Journal of Experimental Medicine). Sodium is the big one to replace. Fire Salt replaces it, with magnesium and potassium in the same stick.
Sauna sweat isn't a "detox." Your liver and kidneys do that job. Sweat is your body cooling itself, and the salt you lose needs to come back.
When Fire Salt helps most after a sauna
| Your sauna habit | What to drink |
|---|---|
| Quick session, a few times a week | Water before. Fire Salt after if you sweated hard or the session ran long. A salty meal helps too. |
| Long sessions or 3 or more rounds | Water between rounds, one Fire Salt stick after |
| Sauna right after a hard workout | One Fire Salt stick after. You're stacking two sweat sessions. |
| Daily sauna plus training, or a hot job | Fire Salt most days |
| Salt lines on your towel or shirt, or you feel wiped out after | Fire Salt every session |
Best electrolytes for sauna (compared)
| Fire Salt Essential Hydration (Our pick) | LMNT | Saltivate | Liquid I.V. Sugar-Free | |
|---|---|---|---|---|
| Sodium | 670 mg | 1,000 mg | 800 mg | 510 mg (per Liquid I.V.'s FAQ) |
| Potassium | 190 mg | 200 mg | 240 mg | 380 mg |
| Magnesium | 90 mg | 60 mg | 60 mg | Not listed |
| Coconut water | Yes | No | No | No |
| Sugar | 0 g | 0 g | 0 g | 0 g |
| Sweetener | Stevia | Stevia | Reb M | Allulose |
| Flavors | 11 plus variety pack | About a dozen | Several | About a dozen |
| Per stick | ~$1.41 (32 for $44.99) | $1.50 (30 for $45) | ~$1.33 (30 for $39.99) | ~$1.56 (14 for $21.84) |
Why Fire Salt is our pick for sauna
- Sodium where you need it. 670 mg per stick replaces the salt you sweat out.
- The most magnesium in the table. 90 mg, 50% more than LMNT or Saltivate.
- Coconut water powder. The only one here with it.
- Zero sugar. You haven't burned much fuel sitting in heat, so you don't need sugar water.
- A milder drink, cold. A third less sodium than LMNT, so it's easy to sip a full bottle after a hot session.
- 11 flavors. Make it the drink you look forward to after the heat.
- Made in the USA, per Fire Salt, with a 30-day money-back guarantee.
The others, one line each
- LMNT has 1,000 mg sodium. If you're doing very long sessions and sweat very salty, it works. Full breakdown: Fire Salt vs LMNT.
- Saltivate has 800 mg sodium at about $1.33 a stick. If price per stick comes first, it works.
- Liquid I.V. Sugar-Free has the most potassium (380 mg). If potassium is your focus, it works.
How much should you drink?
Weigh yourself before and after (dry, no towel). Every 1 kg (2.2 lb) lost is about 1 liter of fluid. The American College of Sports Medicine suggests drinking about 1.5 liters for every kilogram lost when you need to rehydrate quickly, because you keep losing some through urine. Sip it over the next hour or two. Don't chug.
Do you need magnesium after a sauna?
You lose some magnesium in sweat, far less than sodium. Sodium comes first. Fire Salt gives you both: 670 mg sodium and 90 mg magnesium in the same stick.
Do you need sugar after a sauna?
Usually not. Some sauna guidance includes carbs in rehydration drinks, which makes sense if you also trained hard or haven't eaten. For most people, a zero-sugar electrolyte like Fire Salt plus your next meal covers it.
A simple Fire Salt sauna routine
- Glass of water in the hour before.
- Session. Water between rounds if you do more than one.
- After: one Fire Salt stick in 16 to 32 oz of cold water. Sip it over the next 30 to 60 minutes.
- Eat a normal meal.
Sauna safety basics
- Skip alcohol before and during.
- Get out if you feel dizzy, sick or confused.
- If you're pregnant, have a heart condition or low blood pressure, or take medication that affects heat tolerance, ask your doctor first.
- High blood pressure or a low-sodium diet? Talk to your doctor before using any high-sodium electrolyte.
The bottom line
The sauna takes water and salt. Fire Salt puts back sodium, magnesium and coconut water in one zero-sugar stick, with 11 flavors to pick from. Mix it cold, sip it after, and you're done.
Shop Fire Salt Essential Hydration, or start with the 6-stick sampler.
Related
- Built for Heat
- Best Electrolytes for Hot Jobs
- Best Electrolytes for Firefighters
- Fire Salt vs Liquid I.V. Sugar-Free vs Saltivate
Sources
- Podstawski R et al. Sauna-induced body mass loss in young sedentary women and men. The Scientific World Journal, 2014. https://doi.org/10.1155/2014/307421
- Podstawski R et al. Correlations between repeated use of dry sauna for 4 x 10 minutes, physiological parameters, anthropometric features, and body composition. IJERPH, 2019. https://pmc.ncbi.nlm.nih.gov/articles/PMC6360547/
- Hoshi A et al. Concentrations of trace elements in sweat during sauna bathing. Tohoku J Exp Med, 2001. https://www.jstage.jst.go.jp/article/tjem/195/3/195_3_163/_article/-char/en
- American College of Sports Medicine. Exercise and fluid replacement position stand, 2007.
- Brand specs: drinkfiresalt.com, drinklmnt.com, saltivate.com, liquid-iv.com, checked October 8, 2026.
Brand names are trademarks of their owners. Fire Salt is not affiliated with them. Fire Salt is not intended to diagnose, treat, cure, or prevent any disease.
Frequently asked questions
What's the best electrolyte for sauna?
Our pick is Fire Salt Essential Hydration: 670 mg sodium, 90 mg magnesium and coconut water in one zero-sugar stick. If you want maximum sodium for very long sessions, LMNT has 1,000 mg.
Do I need electrolytes after a sauna?
If you did long or repeated rounds, used the sauna after a workout, use it daily, or sweat heavily, yes. Sweat is mostly water and salt, and water alone doesn't replace the salt. One Fire Salt stick in 16 to 32 oz of cold water after your session covers it.
How much do you sweat in a sauna?
Research on 20 minutes in a dry sauna found body mass losses from about 0.24 kg to 0.82 kg, depending on body size. About 0.5 liters is a typical session. Longer sessions and bigger people lose more.
What should I drink after a sauna?
Water plus a zero-sugar electrolyte with real sodium, like Fire Salt. Weigh yourself before and after, and drink about 1.5 liters for every kilogram lost, spread over the next hour or two.
Should I drink electrolytes before a sauna?
A glass of water in the hour before is a good start. If you're going in after a hard workout or for long rounds, a Fire Salt stick beforehand helps you start topped up.
Do you lose magnesium in a sauna?
A little. Sweat contains small amounts of magnesium, far less than sodium. Fire Salt has 670 mg sodium and 90 mg magnesium, so you cover both.
Does sweating in a sauna detox your body?
No. Your liver and kidneys clear waste. Sweating is how your body cools down. Sweat is mostly water and salt, which is why replacing sodium after a long session makes sense.
