The results of a randomised controlled trial showed that inhaling hot steam in a sauna has no significant impact on symptoms of a common cold.

Of the 157 study participants suffering from a cold, those who had inhaled hot air in the sauna did not show a significant difference in the severity of their symptoms compared with participants who had inhaled room temperature air in the same environment.

A 2017 analysis of six trials supported these findings. It concluded that exposure to heated, humid air did not harm nor benefit people suffering with a common cold.

A 2020 article in medical journal The Lancet that referenced the earlier analysis said folk theories claiming that steam loosens mucus, opens nasal passages, and reduces mucosal inflammation all remain unproven.

There’s no evidence that heat inhibits the replication of cold viruses, either, it added.

Relief is temporary, and also subjective

Several participants from the Australian trial reported a pleasant warming in the face, as well as lessened headache symptoms, after their sauna experience, the researchers noted.

Any such moments of relief are fleeting, though, and don’t directly combat the root cause of your cold: viruses. Sensations of ease experienced in a sauna can be likened to the comfort felt after a warm shower – they don’t alter the course or duration of your illness.

But if you’re not getting better, are you getting worse?

Dehydration and infection risks

The long-held notion that you can “sweat out a cold” is scientifically unsound. What’s more, extended exposure to high temperatures in saunas that causes that sweating can lead to dehydration, which can worsen existing cold symptoms.

The Mayo Clinic’s top tip for battling a cold is to stay hydrated.

Trying to get over a cold, a time when your immune system is already weakened, in a shared space like a sauna puts you at risk of getting even more sick. You risk infecting other sauna users, too.

Saunas may prevent a cold

While having a sauna when you’re already suffering from a cold may not help you recover more quickly, studies suggest that having regular sauna baths may help keep colds and other respiratory conditions at bay.

A 2017 study published in the European Journal of Epidemiology involving 1,935 sauna-going men aged 42 to 61 found a link between frequent sauna use and a reduced risk of acute and chronic respiratory conditions.

This echoed a study from 1990 in the Annals of Medicine that compared 25 volunteers who had regular saunas over six months with a group of 25 who did not.

There were significantly fewer episodes of common cold in the sauna group.

If your cold symptoms take a turn for the worse, then you know it’s time to consult a trusted healthcare professional.