Drinking the same volume of fluid you lost in a sauna leaves you short. Restoring fluid balance takes around 150% of fluid lost, spread over the next two to six hours (Better Health Channel, Victorian Government, retrieved August 2026).
This guide sets out a sauna aftercare routine for the hour or two after you step out of the heat, from the cool-down through to rehydration and skin. If you're new to sauna, our beginner's guide to sauna covers your first session.
Key Takeaways
- Sit down for the first few minutes. The blood vessels near your skin are still dilated and your blood pressure can be unsteady.
- Cold water immersion after a sauna raises blood pressure acutely. In one trial it was tolerated by cardiac patients with no complex arrhythmias (Radtke et al., 2016).
- Aim to replace around 150% of the fluid you lost, over two to six hours, with some sodium.
- Leave the alcohol. It was involved in half of Finnish sauna fatalities over a 13-year period (Kenttämies & Karkola, 2008).
- Heat raises the rate your skin loses water. Moisturise once you have stopped sweating.
- Air your hat out. Give it 24 to 48 hours to dry.
how should you cool down after a sauna?
Gradually, and sitting down for the first few minutes. Heat leaves the blood vessels near your skin dilated, so standing up quickly can drop your blood pressure. Sports Medicine Australia's guidance for someone showing signs of heat illness is to stop and move them somewhere cool, then begin active cooling. It also notes that drinking alone will not prevent heat illness (Sports Medicine Australia, 2025, retrieved August 2026).
Most people cool in stages. Step out, sit in the air for a few minutes, then rinse. Research protocols follow the same staged pattern. A 2025 trial in 28 healthy women used three ten-minute sauna rounds separated by ten minutes of cooling. Heart rate and blood pressure stayed stable through those cooling phases (Scientific Reports, 2025, retrieved August 2026).
Dizziness, light-headedness or confusion after a session means stop and cool down properly. Those are early signs of heat illness, and they are the point at which the session is over for the day.
is a cold plunge safe straight after a sauna?
For healthy adults, generally yes, but check with your healthcare professional. It can be a heavy cardiovascular load. In a 2016 trial, 37 men took two sauna exposures at 80°C followed by head-out immersion in 12°C water. After the immersion, systolic blood pressure rose significantly in every group, along with heart rate and cardiac output (Radtke et al., European Journal of Preventive Cardiology, 2016, retrieved August 2026).
Twelve of those men had chronic heart failure and 13 had coronary artery disease. The immersion provoked no complex arrhythmias and no excessive adrenergic activity in any of the three groups.
If you're going to do the cold plunge, sit for a minute or two before you get in, and keep the first plunge short. If you have a heart condition or high blood pressure, ask your doctor before adding cold plunges to a sauna routine.
how much should you drink after a sauna?
Generally, around 150% of what you lost, spread over two to six hours. Matching your losses one for one leaves you short, because some of what you drink leaves as urine before it is absorbed (Better Health Channel, retrieved August 2026). The underlying research is Shirreffs and colleagues, published in Medicine & Science in Sports & Exercise in 1996.
How much you lose depends on the sauna and on you. In one Polish study, 45 overweight sedentary men completed four ten-minute rounds at 90 to 91°C and lost a mean of 0.65 kg of body mass across the hour (Podstawski et al., BioMed Research International, 2019, retrieved August 2026). A larger study by the same group, covering 674 students, found the loss scaled with body mass index, so heavier participants lost the most (The Scientific World Journal, 2014, retrieved August 2026).
Weighing yourself before and after a session gives you a number for your body and your sauna. As a rough conversion, a kilogram of body mass lost is about a litre of fluid.
Over-hydration has its own limit. Drinking well past your losses dilutes blood sodium, and Better Health Channel notes that in rare severe cases over-hydration has been fatal. Spread the fluid across the afternoon in smaller amounts. Don't overdo it.
do you need electrolytes, or is water enough?
Sodium helps you hold onto the water you drink, which is why rehydration research pairs fluid with salt. How much sodium you lose varies widely between people. In 157 marathon runners, mean sweat sodium was 42.9 mmol/L, with a standard deviation of 18.7 and a range of 7.0 to 95.5. About one in five sat above 60 mmol/L (Baker et al., Journal of the International Society of Sports Nutrition, 2016, retrieved August 2026).
That study measured runners under exercise conditions, so read the numbers as an indication of how much people differ. After a short session, water and an ordinary meal will cover it. After a long session, or several rounds, salted food or an electrolyte drink might help.
Alcohol is worth skipping. Deaths in saunas are rare - Finnish forensic records from 1990 to 2002 put the rate below two per 100,000 people a year, and 51% were natural deaths (Kenttämies & Karkola, Journal of Forensic Sciences, 2008, retrieved August 2026). However, alcohol use features in some sauna fatalities. Alcohol was involved in half of all cases in the Finnish study. Swedish figures put it at 44% (Netherlands Heart Journal, 2015, retrieved August 2026).
what does sauna heat do to your skin?
It raises the rate at which your skin loses water and lifts its surface pH. In 50 healthy volunteers, ten minutes of hand immersion at 41.3°C more than doubled transepidermal water loss, from 25.75 to 58.58 g/m²/h. Surface pH rose from 6.33 to 6.65 and redness increased by around 15% (Herrero-Fernandez et al., Journal of Clinical Medicine, 2022, retrieved August 2026).
That study immersed hands in hot water, so the mechanism differs from whole-body dry heat with sweating. It is the closest peer-reviewed measurement available.
Over the longer run, regular sauna bathing has not been found to dry out skin. A review in the American Journal of Medicine reports that it can soften and lift the scale on psoriasis plaques. The same review notes that sweating can increase itching for people with atopic dermatitis (Hannuksela & Ellahham, 2001, retrieved August 2026).
Rinse the sweat off under a lukewarm shower, pat dry, and moisturise while your skin is still slightly damp. Wait until you have stopped sweating, or the product might slide straight off.
| When | What to do | Why |
|---|---|---|
| First few minutes | Sit down, cool in the air | Vessels near the skin are still dilated and blood pressure is unsteady |
| Cold plunge, if you use one | Keep the first one short | Immersion at 12°C raised systolic blood pressure in every group tested (Radtke et al., 2016) |
| After the rinse | Moisturise once you have stopped sweating | Heat more than doubled water loss through the skin barrier (Herrero-Fernandez et al., 2022) |
| Next two to six hours | Aim to drink about 150% of what you lost, with sodium | Some of what you drink is passed as urine before it is absorbed |
| Same evening | Skip the alcohol, and leave an hour or two before bed | Alcohol featured in half of Finnish sauna deaths (Kenttämies & Karkola, 2008) |
| Afterwards | Air the hat for 24 to 48 hours | Full washing shrinks and warps felted wool |
how to build a sauna aftercare routine
A sauna aftercare routine is short and mostly a matter of order. Sit for two or three minutes before you stand up. Cool in the air, then rinse. Drink steadily through the next few hours, more than you think you lost, with something salty after a long session. Moisturise once you have cooled.
If you use the sauna in the evening, leave an hour or two before bed. A meta-analysis of 17 studies found that passive body heating one to two hours before sleep shortened the time taken to fall asleep by around ten minutes (Haghayegh et al., Sleep Medicine Reviews, 2019, retrieved August 2026). Those trials used warm baths and showers. No equivalent trial on sauna bathing has been published.
If you are pregnant, or you have a heart condition, low blood pressure or a history of heat intolerance, talk to your doctor before building sauna into a weekly routine.
Your hat needs less attention than you would expect. Air it in a well-ventilated spot out of direct sunlight, and give it 24 to 48 hours to dry. Full washing shrinks and warps felted wool, so leave it alone unless there is a mark to spot clean. Our Merino wool sauna hat care guide covers spot cleaning and reshaping.
When we developed the FELT. hats we settled on 4mm as the practical middle: enough insulation for a long session, light enough to dry between uses. Both The Classic and The Modern use it. Our guide to the benefits of a sauna hat covers what it does in the heat, and why merino wool is the gold standard covers the fibre itself.
For the setup around the session, see our complete guide to setting up a home sauna routine and the essential home sauna accessories checklist. If you are using the heat for training, sauna for recovery covers timing and the evidence, and our guide to the science-backed health benefits of sauna covers the longer-term research.
common questions about sauna aftercare
how long should you cool down after a sauna?
Give it at least ten minutes of cool down time outside the sauna before you consider the session finished. Sauna research protocols commonly use ten minutes of cooling between rounds. In a 2025 trial in 28 healthy women, heart rate and blood pressure stayed stable across those phases. Sit down first: your blood pressure takes a few minutes to settle after the heat.
should you shower straight after a sauna?
Generally yes, once you have sat and cooled for a few minutes. A lukewarm rinse clears the sweat before it dries on the skin. Cold water is fine for healthy adults, and it is a cardiovascular load. In a 2016 trial, immersion in 12°C water after a sauna raised systolic blood pressure, heart rate and cardiac output in every group tested. That included men with heart failure and coronary artery disease.
how much water should you drink after a sauna?
Around 150% of the fluid you lost, spread over the following two to six hours, with some sodium alongside it. Matching your losses one for one leaves you short, because part of what you drink is passed as urine before it is absorbed. Weighing yourself before and after a session gives you a figure for your own body: a kilogram of body mass is roughly a litre of fluid.
is it bad to drink alcohol after a sauna?
Leave it out. Fatalities in saunas are rare, at under two per 100,000 people a year in Finnish forensic records from 1990 to 2002, though alcohol features in a large share of them. Swedish data puts the figure at 44%. Alcohol is also a diuretic, so it adds to the fluid you need to replace.
how do you look after a sauna hat after a session?
A day or two in the open air, away from direct sun, is usually enough. Merino wool is naturally odour-resistant, so airing is all it needs between sessions. Avoid washing a felted wool hat, as water saturation and agitation cause it to shrink and lose its shape. Spot clean marks with cool water and a wool-safe detergent.
