Sauna and Colds: Why the Time to Start Is Before Cold Season

Most people think about colds once they have one. They reach for a remedy, wait it out, and promise themselves they will do something about it before next winter.

The research on sauna and colds points to a different approach, because the one study that tracked it closely found that the benefit did not show up right away. It took months. That changes when it makes sense to start.

The study

In 1990, researchers in Austria ran a six-month study published in the Annals of Medicine to test a simple question: do people who use a sauna regularly catch fewer colds?

Fifty volunteers were split into two groups. Twenty-five used a sauna regularly over the six months. The other 25 did not use a sauna or anything comparable. The researchers recorded every cold in both groups, along with how long each one lasted and how bad it was.

By the end of the six months, the sauna group had caught 33 colds. The group without sauna had caught 46. That is roughly 28% fewer colds in the sauna group. The sauna group also logged far fewer days with cold symptoms overall: 221 compared with 343.

Those totals are interesting. The timing is more interesting.

The first three months: no difference

For the first half of the study, the two groups looked about the same. The sauna users caught colds at roughly the same rate as everyone else.

There was no early payoff. A few weeks of sauna sessions did not produce a noticeable change. If the study had ended at the three-month mark, it would have looked like sauna made little difference.

The last three months: less than half

Then the pattern shifted. In the second half of the study, the sauna group had less than half as many colds as the control group.

Whatever was happening, it appears to have needed time to build. Regular heat exposure over a period of months, not a handful of sessions, is what preceded the drop.

Researchers have not pinned down why. Sauna exposure raises core temperature, and repeated heat stress is known to affect how the body regulates its stress and inflammatory responses, but the study did not measure immune markers, so any specific mechanism is an educated guess. What the data shows is the timing, not the reason.

What did not change

Here is the finding that often gets left out: when sauna users did catch a cold, it lasted just as long and felt just as bad as the colds in the other group. The researchers found no meaningful difference in duration or severity.

So the effect, if it is real, is about catching fewer colds. It is not about softening the ones you get.

That matches what research shows about using heat once you are already sick. A Cochrane review of heated, humidified air for the common cold found no clear evidence that breathing warm, moist air relieves cold symptoms. A sauna session is not a treatment for a cold you already have. If there is a benefit, it comes from regular use before you get sick.

The bigger picture

The Austrian study is small. A much larger body of data points in the same direction.

Researchers following the Finnish cohort behind the long-running sauna and cardiovascular research published a prospective study in the European Journal of Epidemiology on sauna use and respiratory disease. They followed 1,935 men aged 42 to 61 for a median of 25.6 years and recorded 379 hospital-diagnosed cases of chronic obstructive pulmonary disease, asthma, or pneumonia.

Compared with men who used the sauna once a week or less, men who used it two to three times a week had a 27% lower risk of respiratory disease. Men who used it four or more times a week had a 41% lower risk. The results held after adjusting for major respiratory risk factors.

These are serious, hospital-diagnosed conditions, not the common cold, so the two studies are measuring different things. But the direction is the same: regular, frequent sauna use is associated with fewer respiratory problems over time, and more frequent use tracks with a larger difference.

The honest part

Both studies have real limits.

The Austrian cold study was small, with 25 people per group, and it was not randomized: participants were not randomly assigned to sauna or no sauna. The study's own lead author, Edzard Ernst, has since described it as small, unfunded, non-randomized, and lacking objective endpoints. The statistical result was also borderline, right at the edge of significance.

The Finnish data is observational. Men who use a sauna four or more times a week may differ in other ways from men who use it once, and the researchers can only adjust for the factors they measured. It shows a link, not proof.

So the honest summary is this: two very different studies, decades apart, both point toward regular sauna use being associated with fewer respiratory illnesses. That is promising. It is not a guarantee, and it is not a replacement for vaccination, handwashing, sleep, or any other well-established way to stay healthy through winter.

And one rule is clear: skip the sauna if you already have a fever. Your body is already raising its own temperature to fight infection, and adding external heat puts extra strain on your cardiovascular system. Wait until the fever has fully passed.

The timing

If the benefit in the Austrian study took about three months to appear, then when you start matters.

Starting a sauna routine in the middle of winter, after colds are already circulating through your home and office, means spending the worst weeks of the season in the window where the study saw no difference. Starting in the fall means the three-month mark lands in deep winter, when it is most useful.

Which means the time to start is now.

Frequency: The Finnish data showed lower risk at two to three sessions a week and the lowest risk at four or more. Build toward a routine you can keep through the whole season.

Duration: 15 to 20 minutes per session is a practical, well-tolerated target.

Consistency over intensity: The pattern in both studies is about regular use over months and years. A habit you keep through February matters more than an intense week in October.

Hydration: Drink water before and after every session.

When to skip: Do not use a sauna with a fever, and check with your doctor first if you have a heart condition, low blood pressure, or are pregnant.

A sauna you will use all winter

A routine that has to last through the coldest months needs a sauna that is easy to get to when it is dark at 5 p.m. and well below zero outside.

For traditional Finnish heat outdoors, the Outdoor Sauna Pro and Outdoor Sauna XTREME are cold-climate rated for permanent outdoor installation, heat up to 110°C, and have Wi-Fi control, so you can start the preheat from inside the house and walk out to a sauna that is already hot. The Pro seats 2 to 3 people and the XTREME seats 4 to 6. For heat from a real fire, there is the XTREME Woodburning Sauna.

If you would rather never step outside in January, an indoor sauna removes that barrier entirely. The Hybrid Sauna runs traditional and infrared heat independently or together, from 21 to 90°C, seats 4 to 6, and preheats from the Coldture app. The Pod Sauna seats 1 to 2 and plugs into a 120V / 20A outlet with no permanent install, and the Corner Pod fits 2 to 3 people into the corner of a room on a dedicated 220V connection. The Pod Lite rounds out the indoor infrared range.

Browse the full sauna collection to find the one that fits your space.

Start before cold season. Not during it.

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This content is educational information, not medical advice. Consult your physician regarding your individual circumstances, especially if you have a cardiovascular condition, low blood pressure, or are pregnant. Do not use a sauna if you have a fever. Sauna use is a complementary wellness practice, not a treatment or prevention for colds, respiratory disease, or any other illness.

Study citations

1. Ernst E, Pecho E, Wirz P, Saradeth T. (1990). "Regular sauna bathing and the incidence of common colds." Annals of Medicine, 22(4):225-227. https://doi.org/10.3109/07853899009148930
2. Kunutsor SK, Laukkanen T, Laukkanen JA. (2017). "Sauna bathing reduces the risk of respiratory diseases: a long-term prospective cohort study." European Journal of Epidemiology, 32(12):1107-1111. https://doi.org/10.1007/s10654-017-0311-6
3. Singh M, Singh M, Jaiswal N, Chauhan A. (2017). "Heated, humidified air for the common cold." Cochrane Database of Systematic Reviews, CD001728. https://doi.org/10.1002/14651858.CD001728.pub6