The best thing to wear in an infrared sauna is as little as possible: a loose-fitting swimsuit, lightweight shorts, or nothing at all. Infrared saunas work by warming your body directly through radiant energy rather than superheating the air around you, which means anything draped over your skin can interfere with how that energy reaches you and how effectively your body cools itself through sweat. The practical choices come down to fabric type, fit, and a few items you should leave outside the sauna entirely.
Why Less Fabric Means Better Results
Clothing acts as a layer of insulation between your skin and the environment. In warm conditions, that insulation causes your body temperature to rise faster while simultaneously creating a barrier to sweat evaporation, which is your primary cooling mechanism.1PubMed. Clothing and thermoregulation during exercise In an infrared sauna, this dynamic plays out in a specific way: the infrared panels emit radiant energy that penetrates the skin. Fabric sitting on top of the skin absorbs some of that energy before it reaches you, and then traps the moisture your body produces in response.
As your sweat rate increases, moisture builds up in the fabric. That saturated clothing doesn’t just feel uncomfortable. Research using thermal manikins has shown that as clothing moisture content rises, it adds resistance to the transfer of heat and sweat away from the skin, which can adversely affect skin temperature regulation.2Building and Environment. Exploring the effect of clothing moisture content on heat and moisture transfer from the human body using a sweating thermal manikin In plain terms, wet clothing sticks to your skin and makes it harder for your body to manage its own temperature, which is the opposite of what you want in a controlled heat session.
Environmental factors like humidity, airflow, and what you’re wearing all affect whether sweat molecules can successfully evaporate once they leave your skin.3PubMed Central. Sweat evaporation in humans: A molecular and thermodynamic perspective An infrared sauna is already a low-airflow environment. Adding a layer of clothing further reduces the surface area available for evaporation and increases liquid retention against the skin. If your goal is to get the full benefit of the session, you want to minimize anything that gets between the infrared energy and your skin or traps sweat against you.
Best Fabric Choices If You Prefer to Wear Something
Not everyone is comfortable sitting nude in a sauna, whether because of shared facilities, personal preference, or hygiene considerations. If you’re going to wear something, the fabric matters more than you might expect. The general advice is to reach for natural fibers like cotton, linen, or bamboo. These fabrics are breathable, absorb moisture without becoming a sealed barrier, and don’t introduce chemical concerns when heated.
You might assume that moisture-wicking polyester would be the better call, since athletic wear is designed to move sweat away from the skin. But the evidence on whether polyester actually outperforms cotton in hot conditions is surprisingly weak. A pilot study comparing polyester and cotton T-shirts during exercise in heat found no meaningful difference in thermoregulatory, perspiratory, or cardiovascular responses between the two fabrics.4PubMed. Physiological effects of exercise in heat while wearing a polyester versus cotton T-shirt in physically active men with obesity: a pilot study The takeaway is that for a sauna session, the “performance” features of synthetic athletic wear don’t buy you much. And as we’ll see in the next section, synthetics can introduce problems of their own.
Whatever you choose, keep it loose. Tight-fitting garments press fabric against your skin, which reduces the air gap that helps with cooling. A baggy cotton tank top or a pair of loose shorts lets air circulate and gives sweat room to evaporate. Avoid anything with elastic waistbands that dig in or compression elements that seal against the skin.
What Synthetic Fabrics Can Release When Heated
This is where the advice to avoid synthetics in a sauna gets more pointed. Fabrics like spandex, nylon, and polyester are manufactured with chemical dyes, finishes, and processing agents. Under normal room-temperature conditions, these chemicals stay bound in the fabric. But heat and moisture change the equation. Spandex, for instance, does not absorb sweat. When you perspire underneath it, the combination of heat and trapped moisture can cause chemicals from dyes and formaldehyde-based finishes to migrate out of the fabric and onto your skin. Contact dermatitis from spandex is a well-documented side effect, and the inability of the fabric to absorb sweat can also create conditions favorable to bacterial growth.5Advanced Research in Textile Engineering. Toxicity of Synthetic Fibres & Health
An infrared sauna amplifies this risk. The temperatures typically range from around 45°C to 65°C (roughly 110°F to 150°F), which is lower than a traditional Finnish sauna but still well above ambient. Combined with sustained sweating over a 20- to 40-minute session, the conditions are ideal for drawing chemical residues out of synthetic fabrics. If you’ve ever noticed an odd smell from workout clothes in high heat, that’s a hint of what’s happening at the chemical level.
The practical advice is straightforward: leave the yoga pants, sports bras made of synthetic blends, and spandex shorts outside the sauna. If you need coverage, opt for unbleached, undyed cotton or linen when possible. If your swimsuit is synthetic (and most are), that’s generally a low-risk choice for short sessions since swimwear is designed for wet conditions, but a simple cotton alternative is still the safer bet for regular use.
Items to Leave Outside the Sauna
Beyond fabric selection, a few categories of items deserve specific attention.
- Metal jewelry: Rings, necklaces, watches, and piercings heat up faster than your skin does. Metal conducts heat efficiently, and in an infrared sauna, metal objects absorb infrared radiation and can become uncomfortably hot against the skin. This is especially true for items sitting close to the panels. Remove all metal jewelry before entering.
- Glasses and sunglasses: Metal frames heat up for the same reason as jewelry. Plastic frames are less of a concern thermally, but the lenses can fog and the heat may warp cheaper frames over time. Leave them outside if possible.
- Underwire bras: The wire is metal, and it sits against skin that’s actively sweating. This is a recipe for discomfort or mild burns during a longer session.
- Heavy clothing: Sweatshirts, jeans, or layered outfits trap heat, block infrared penetration, and saturate quickly with sweat. There’s no scenario where wearing more clothing improves an infrared sauna session.
- Shoes and socks: Most infrared saunas are designed for bare feet. Socks trap moisture against your feet, and shoes are unnecessary. If hygiene is a concern, bring a clean towel for the floor.
A general rule: if an item has metal components, chemical treatments, or heavy insulation, it doesn’t belong in the sauna.
Transdermal Patches and Medication Safety
This is a genuinely important safety concern that most sauna guides gloss over. If you wear any kind of medicated patch on your skin, an infrared sauna can dramatically alter how much drug enters your bloodstream. Research on nicotine patches found that applying controlled heat at 43°C caused skin blood flow to increase up to ninefold, which boosted nicotine absorption by up to thirteen times the normal rate.6PubMed Central. Effect of local controlled heat on transdermal delivery of nicotine That’s not a subtle change. It means a patch designed to deliver a steady, controlled dose over many hours could dump a much larger amount into your system during a single sauna session.
The stakes get higher with more potent medications. A case report documented a fatal accidental fentanyl overdose in a person who wore a transdermal fentanyl patch into a sauna. The heat increased subcutaneous blood circulation, which dramatically accelerated the rate at which fentanyl moved from the patch into the bloodstream.7PubMed. Death in Sauna Associated With a Transdermal Fentanyl Patch This applies to all transdermal patches, including those for pain management, hormone replacement, motion sickness, and nicotine cessation. Remove any medicated patch before entering a sauna, and consult your prescribing doctor about how to handle the interruption in dosing.
This concern extends beyond patches to any topical medication that absorbs through the skin. Prescription creams, gels, and ointments that contain active pharmaceuticals may absorb faster in a heated environment. If you use any topical medication regularly, apply it after the sauna session rather than before.
The Towel Question
Whether you wear clothing or not, a towel is the one thing you should always bring into an infrared sauna. Most sauna manufacturers recommend sitting on a towel to absorb sweat and protect the wood surfaces. A second towel for your face and neck is useful for comfort. Choose cotton towels, not microfiber. Microfiber is synthetic and shares the same chemical-leaching concerns as other synthetic fabrics when subjected to sustained heat and moisture.
Some people drape a towel over their lap or shoulders for modesty in shared spaces, which works fine as a middle ground between full clothing and going bare. A cotton towel is breathable, absorbs sweat without becoming a sealed barrier, and doesn’t introduce chemical concerns. If your sauna facility provides towels, they’ve likely been laundered with commercial detergents and fabric softeners. For regular sauna users who are sensitive to fragrances or chemical residues, bringing your own towels washed with a fragrance-free detergent is worth considering.
Nude vs. Clothed Sessions
If privacy allows, going nude in an infrared sauna gives you the most direct exposure to the infrared energy and the least interference with your body’s natural cooling. There’s nothing between the panels and your skin, no fabric absorbing infrared radiation, no clothing trapping sweat, and no chemical concerns from textiles. For a home sauna or a private session, this is the simplest and most effective approach.
In shared or commercial settings, the norms vary widely. Some facilities require swimwear. Others provide disposable coverings. A few, particularly those modeled on Scandinavian traditions, expect nudity. Check the facility’s policy before your session. If swimwear is required, a simple cotton bikini, cotton shorts, or a cotton wrap is your best option. Avoid bringing your gym clothes into the sauna just because they’re what you have on hand.
One consideration that comes up for people new to infrared saunas: the panels in an infrared sauna emit energy at specific wavelengths (far-infrared, near-infrared, or a combination). This energy penetrates the skin to varying depths depending on the wavelength. Clothing doesn’t just block heat in the way a winter coat does. It absorbs some of the infrared energy, converts it to heat in the fabric, and then transfers that heated fabric against your skin, which is a less efficient pathway than direct infrared absorption. The effect is most pronounced with thicker or tighter garments.
Preparing Your Skin Before a Session
What you put on your skin before entering an infrared sauna matters almost as much as what you wear. Lotions, sunscreens, and heavy moisturizers can create a film on the skin that interferes with sweating and may break down unpredictably in heat. Makeup, particularly products containing synthetic pigments or heavy metals in mineral formulations, can clog pores and prevent normal perspiration. The ideal is to enter the sauna with clean, bare skin.
Deodorant and antiperspirant deserve a specific mention. Antiperspirants work by blocking sweat glands with aluminum-based compounds. Wearing antiperspirant into a sauna directly opposes what you’re there to do. If you’re concerned about odor in a shared space, a quick rinse beforehand is more effective and doesn’t interfere with the session. Regular deodorant (without antiperspirant) is less of a concern but still adds a layer of chemicals to heated skin.
For people with sensitive skin or conditions like eczema, the combination of heat, sweat, and any product residue on the skin can trigger flare-ups. A pre-sauna shower with mild soap removes residues from the day and gives you a clean starting point. Post-sauna, a cool rinse followed by a gentle moisturizer helps replenish the skin barrier that sustained sweating can temporarily compromise.
Contact Lenses, Hair Ties, and Other Small Considerations
Contact lenses can dry out in the warm, low-humidity environment of an infrared sauna. Soft lenses in particular may become uncomfortable as moisture evaporates from their surface. If you wear contacts, consider removing them or at least bringing rewetting drops. Hard or gas-permeable lenses are less affected but can still feel uncomfortable during longer sessions.
Hair ties and headbands are fine if they’re fabric-based. Metal hair clips or bobby pins will heat up and can become uncomfortable or burn the scalp. If you have long hair and want to keep it off your neck, a loose cotton scrunchie or cloth headband works well. Some regular sauna-goers bring a small cotton towel to wrap their hair, which also absorbs sweat from the scalp and hairline.
Silicone items like wedding ring alternatives or fitness tracker bands hold up well in infrared sauna temperatures and don’t conduct heat the way metal does. If you prefer to keep a ring on, a silicone band is a reasonable swap for your session. Fitness trackers themselves are a different question: while many are rated for brief heat exposure, sustained temperatures above 45°C can affect battery life, sensor accuracy, and adhesive integrity over time. Most manufacturers don’t warranty their devices for sauna use, so proceed with that in mind.