Why Does My Sauna Smell? (10 Most Common Reasons – Both New & Old)

Ah, time to hit the sauna and relax. Sit back, forget the day, enjoy the heat, and the…smell?

A smelly sauna makes it impossible to enjoy your session. If you’re at a gym or spa sauna, there isn’t much you can do (and it’s probably a sign that you should find another sauna). But if your home sauna is starting to stink up, don’t fret. There are a lot of possible reasons for the stench, but that means there are a lot of fixes too.

Your sauna may smell for many reasons including mold, sweat, bacteria, dirt, burning wires, expired essential oils, wearing your day clothes, or improper ventilation. All of these smells can be avoided with proper preventative measures and a thorough, consistent cleaning regimen. New saunas may require a few runs to purge any residual chemicals.

Keep reading to learn the top 10 reasons why a sauna smells and what you can do to fix it!

10 Reasons why a sauna smells or has a bad odor

Foul odors should always be addressed because some of them can represent health risks (mold and chemicals) or even danger (burning wires).

Here are the top 10 reasons your sauna smells or has a bad odor:

  • Mold
  • Sweat
  • Bacteria
  • Dirt
  • Expired essential oils
  • Wearing your day clothes
  • Improper ventilation
  • Burning wires
  • Production process residue
  • Stain or varnish

With correct cleaning and prevention, these problems will go away quickly. A few of them – like mold and burning wires – may require more extensive care, but it’s well worth avoiding the smell and (more importantly) danger.


A warm, damp, stagnant environment is any mold’s dream. Unfortunately, your sauna provides just that.

Saunas develop mold because they are warm and moist. Mold is dangerous for humans to breathe in and needs to be taken care of right away. In the worst-case scenario, moisture can get into your insulation and allow mold to grow, requiring you to re-insulate your sauna.

Mold smells musty and earthy. If you’ve ever dried a load of laundry, only to discover it didn’t fully dry, you probably already know what mold smells like.

Mold is dangerous and can cause itchy eyes or skin, wheezing, a stuffy nose, or asthmatic reactions.

If you’ve cleaned your sauna top to bottom and still smell mold, you might be in a sticky situation. If your foil vapor barrier has been damaged (or if you didn’t have one at all), the mold may be in your insulation and you’ll have to replace it.


When you’re hot, you sweat. And saunas are hot! But if the sweat isn’t properly cleaned up, it can create quite a stink.

Sweat can make your sauna smell bad if it builds up on the seats. Other people’s sweat will also cause a sauna to smell. Sweat smells bad because it picks up your skin’s bacteria.

It’s customary to sit on a towel in the sauna to avoid getting your sweat on the seats. If you’ve been slacking on this preventative measure, sweat will build up and create a foul odor.

Even if you do sit on a towel, sweat can still penetrate your sauna. Clean your sauna between every use and air dry it to avoid excess moisture.

If you’re out and about in a gym sauna and people hop into the sauna before showering, their sweat will certainly make the sauna smell bad.


Bacteria can grow in many conditions, but they especially thrive when it is hot, moist, and unsanitary.

Bacteria will definitely cause your sauna to smell. The wooden benches in saunas hold onto germs and dirt, which cause microorganisms to multiply. This is why saunas need to be cleaned properly.

Most disease-ridden bacteria grow most quickly in the 41-135 °F (also known as the temperature danger zone), which spells bad news for steam rooms which are typically around 110°F.

If you enjoy a lot of humidity in your sauna, it is extra important to sanitize it after each use.


A little dirt never hurt anyone, right? Wrong!

While dirt itself will not cause a sauna to smell, it can harbor mold and bacteria that will make your sauna smell bad. The dirtier your sauna is, the more likely it is that it will smell.

One teaspoon of productive soil can contain as many as 1 billion bacteria!

Think twice about tracking dirt in and out of your sauna without sweeping it up. You never know what the dirt contains – bacteria, mold spores, parasites, and more. Nothing you want in your sauna, that’s for sure.

Expired essential oils

Despite popular belief, essential oils can get old and smell different over time.

Expired essential oils can smell stale or rancid. Essential oils in their purest form can spoil without smelling bad, but when they are in a carrier oil, the expired carrier oils can create an unpleasant odor.

Carrier oils dilute essential oils and help them stick to the skin. These carrier oils are typically vegetable oils.

Vegetable oils don’t grow mold or rot, but when they go bad they smell rancid. Exposure to water, heat, microbes, and air can all spoil vegetable oils.

Wearing your day clothes

After a long day, it might be tempting to hop right into the sauna in your day clothes. But that’s a bad idea.

Wearing your day clothes can make your sauna smell because all of the dirt, dust, and sweat trapped in your clothes will be loosened by the heat and fill the air.

All of the smells you encounter throughout the day stick to your clothes. Pumping gas into your car, petting your dogs, a musty air conditioner at work…all that – and more – will come loose in your sauna.

Regardless of smell, it’s important to wear clean clothes in the sauna to avoid a buildup of dirt, as previously discussed.

Improper ventilation

Saunas are bound to smell a little bit because of everyone’s sweat, at the very least. That’s where ventilation comes into play. But if you keep those vents closed too long in the hopes of an overly-toasty sauna, you’re sacrificing heat for the smell.

Ventilation is key to reaching the right temperature and having proper airflow. And that airflow is vital to keeping your sauna nice and fresh. Your sauna will smell if you keep the vents closed for too long because there will be no fresh air to cycle out the stuffiness of the sauna.

Burning wires

The only burning smell you want in a sauna is if you’re using an old-fashioned wood-fueled sauna. Electrical burns are a huge red flag.

If you smell burning in your sauna, turn it off immediately and replace your heating element. The smell of burning wires signals that something is very wrong with your heating element.

Not only are the fumes dangerous to inhale, but a failing heating element can cause a fire.

Production process residue

The first time you heat up your sauna, you might notice the smell of chemicals. Don’t worry! This is totally normal.

You might smell residue from the production process evaporate the first time you heat up your sauna. It’s not recommended to sit in your sauna the first time it heats up because these fumes can be toxic.

Residue from the production process may remain on the wood of your sauna when you first have it installed. Run it through a cycle or two to get rid of any chemical remnants so you aren’t breathing them in.

Stain or varnish

New wood stains on your sauna can create a beautiful appearance and thoroughly enhance your sauna experience. But it can also cause a chemical-like smell at first.

When a new stain is applied to your sauna, you will smell chemicals the first few times your sauna heats up. This is because some of the stains is evaporating into the air. The smell will go away after a few sessions.

Fumes from new wood stains are poisonous, so you may want to run your sauna a couple of times after staining before hopping in.

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