When not to use the sauna
Acute illness or fever
If you're already running hot, the sauna will push your core temperature higher and your immune system harder. Stay home, drink fluids, and come back when you've been symptom-free for at least a day.
Recent heart event or unstable cardiovascular disease
Heat raises heart rate and shifts blood pressure. For most cardiovascular conditions in the chronic, well-managed phase, modest sauna use is fine and may even be helpful — but the keyword is well-managed. After a recent infarction, in the weeks following cardiac surgery, with uncontrolled blood pressure or unstable angina: not now. Talk to your cardiologist before you come.
Pregnancy
Recommendations vary by country and trimester. The general advice is to keep core body temperature below 38.9 °C (102 °F) — which a normal sauna session can exceed. If you used a sauna comfortably before pregnancy, ask your doctor specifically about your situation, your trimester, and how long is acceptable. Don't make this call alone.
Alcohol — including the small glass
Alcohol is a vasodilator. So is the sauna. Together they drop blood pressure, increase the risk of fainting, and meaningfully raise the risk of a serious cardiac event. The combination is the most consistent factor in sauna-related deaths in countries that track such things. We will turn you away at the desk if we suspect you've been drinking. Please don't be offended.
Recent hard exercise without recovery
You've finished a long run, you're already dehydrated, your heart rate is still elevated. Adding heat to that picture is unkind to your kidneys and your blood pressure. Drink, eat a small meal, rest for at least an hour, then decide.
Some medications
Diuretics, certain blood-pressure medications, sedatives, and some psychiatric medications change how your body handles heat and dehydration. If you take medication regularly and have not used a sauna before, ask your prescriber whether it's appropriate.
Warning signs to leave the room — now
You don't need to wait for any of these to feel "really bad." Treat them as instructions.
- Lightheaded or dizzy. Step out, sit down somewhere cool, drink water.
- Heart pounding hard or irregular. Out, slowly, no sudden movements.
- Nausea. Out, sip water, sit upright in fresh air.
- Tingling fingers or lips, ringing ears. Out. These are early signs of fainting.
- Sudden cold sweat or clammy skin. Out. This is unusual and not normal.
- Headache that's not just "warm-feeling." Out, hydrate, end the session.
- Confusion or disorientation. This is heat exhaustion. Out, cool down properly, do not finish the session.
If symptoms persist after leaving, getting to a cool room, and drinking water — call the desk. We'd much rather over-react than under-react.
Children and the sauna
Children adapt to heat less efficiently than adults. As a guideline:
- Under 5: not in a hot sauna at all.
- 5–10: short visits only (3–5 minutes), on the lowest bench, with a parent paying full attention.
- 10–15: gradually building up tolerance, but still significantly shorter sessions than adults.
Don't bring a child who is reluctant. The sauna is not a place to win an argument.
Hydration, sensibly
You will lose 0.5–1.5 litres of sweat in a typical session. Drink before, sip during cool-down, drink properly afterward. Plain water is best. Sports drinks are fine if you've sweated heavily. Don't try to "out-drink" the loss in the first ten minutes after leaving — sip steadily over the next hour or two.
Excessive water intake on top of heavy sweating, paradoxically, can cause its own problems (low blood sodium). Most people will never get close to this, but if you find yourself drinking three litres in twenty minutes, slow down.
Cool-down protocol
Don't rush from the sauna directly into a cold plunge if you've never done one. The shock can be substantial — and the heart-rate spike is real. The conservative sequence is:
- Step out of the heat.
- Walk for thirty seconds in the fresh air or a cool corridor.
- Cool shower — start warm, work cooler. Twenty to forty seconds.
- Sit, sip water, breathe slowly.
- Once you're calm, decide whether you want a second round, a cold plunge, or a cup of tea.
The disclaimer, briefly
Nothing on this page is a substitute for a conversation with your doctor about your specific health, medications, and history. If in doubt, ask. We can wait.