What to Wear in a Sauna: Cotton, Linen, Synthetics and Simple Safety
Written and reviewed by The Kriya Yogi · Updated 23 September 2026
Sauna etiquette varies by country and venue: some Finnish and German saunas expect no clothing at all, many gyms require covering, and steam rooms usually mean swimwear. Once you know the venue rule, the fabric question is mostly about heat, moisture and skin comfort rather than chemistry. Here is what actually changes at 80–100°C.
The short answer
In a hot sauna, less fabric and looser fabric is the usual advice: a towel, or clean loose cotton or linen. Synthetics are not proven to be toxic at sauna temperatures, but tight elastic-heavy activewear traps heat and sweat, can rub and may carry prints, coatings or metal trims that become uncomfortably hot. Steam rooms and hot tubs favour swimwear because of hygiene and water.
- A clean cotton or linen towel to sit on is the single most useful item, for hygiene and to protect skin from hot benches.
- Loose cotton or linen breathes and stays soft; heavy soaked cotton is fine for a short session but becomes clammy.
- Polyester and elastane garments are not known to release harmful amounts of anything in a normal sauna, but tight compression fits, thick seams, prints and metal zips or underwires get hot and chafe.
- In steam rooms, hot tubs and pools, venue hygiene rules usually require swimwear, which is nearly always synthetic—that is normal and acceptable.
Start with the venue's rule
Traditional dry saunas in Nordic and German-speaking countries are often used without clothing, with a towel to sit on. Public gyms and hotels typically ask for a towel or light covering. Steam rooms and hydrotherapy areas usually require swimwear. Ask, or read the posted rules; comfort advice cannot override a venue policy.
Why loose natural fabric is the common recommendation
High heat plus heavy sweating makes any close layer feel oppressive. Cotton and linen absorb sweat, feel soft, carry no strong odour when clean and cause no melting or stickiness at sauna temperatures. Linen is especially pleasant because it is stiff enough to stand away from the skin. They are also easy to wash hot, which matters more for hygiene than fibre philosophy.
Where synthetics are genuinely a problem, and where they are not
The realistic issues with wearing activewear in a sauna are mechanical: elastic waistbands and sports bras compress and trap heat, wet synthetic seams rub, silicone grips and plastic prints can feel hot and tacky against skin, and metal fastenings, zips or underwires conduct heat. Dark synthetic swimwear also degrades faster with repeated heat and chlorine exposure.
What is not established is the popular claim that wearing polyester in a sauna 'leaches plastic toxins into your bloodstream' or blocks detoxification. Sweating is thermoregulation, not a purification system, and no human study shows that a sauna session in synthetic clothing causes measurable harm. Prefer cotton or a towel because it is more comfortable and easier to keep clean—not because of a toxin story.
Practical sauna habits that matter more than fabric
Hydration, session length, alcohol avoidance and letting the body cool gradually influence how a sauna feels far more than a fibre label. Regular sauna bathing has been studied mainly in observational Finnish cohorts and small trials, with associations reported for cardiovascular and wellbeing measures; these are associations from specific populations, not a prescription. Anyone pregnant, taking cardiovascular medication, prone to fainting, or living with heart or blood-pressure conditions should ask a clinician before regular heat exposure.
Practical choices
Bring two clean towels
One to sit on, one to dry with; this is the core of sauna hygiene in most venues.
Choose loose over tight
A light cotton or linen wrap, shorts or a simple tee beats compression leggings and a sports bra.
Remove metal and hardware
Take off jewellery, watches and clothing with metal zips, clasps or underwires; metal heats fast.
Skip heavy coatings
Avoid garments with thick plastic prints, silicone grips or waterproof finishes against skin in high heat.
Change afterwards
Shower, dry fully and put on dry clothing rather than cooling down in a soaked layer.
Keep sessions moderate
Start short, drink water, exit if dizzy, light-headed, nauseated or unusually breathless.
Cautions worth reading
- Do not use a sauna during pregnancy, or with heart disease, unstable blood pressure, recent heart attack, or a fainting history, without clinical advice.
- Alcohol and heat together raise the risk of dehydration, fainting and accidents.
- Never treat sauna sweating as detoxification or as a replacement for medical treatment.
- Leave immediately and cool down if you feel faint, confused, sick or your heart rate feels wrong.
Where the evidence stands
Sauna research is dominated by Finnish observational cohorts and small physiological trials reporting cardiovascular and wellbeing associations, with limited controlled evidence and little work on clothing at all. Claims that specific fabrics make sauna use toxic or therapeutic are not supported; comfort, hygiene, heat exposure and individual medical fitness are the evidence-based considerations.
Questions people ask
+ Is it bad to wear polyester in a sauna?
+ What is best to wear in a sauna?
+ Can I wear gym clothes in a sauna?
+ Does sweating in a sauna remove toxins?
Sources
- Laukkanen, Laukkanen & Kunutsor, 2018. Cardiovascular and other health benefits of sauna bathing: review of the evidence. Mayo Clinic Proceedings.
- Hussain & Cohen, 2018. Clinical effects of regular dry sauna bathing: a systematic review.
- Morris et al., 2022. Sports clothing, thermoregulation, comfort and performance in the heat: narrative review.
- American College of Obstetricians and Gynecologists. Exercise during pregnancy (heat exposure guidance).
Pregnancy, cardiovascular disease, low blood pressure, medication that affects heat tolerance, and any history of fainting all require personal medical guidance before regular heat bathing. This article is educational and does not diagnose or treat a condition.