Do Saunas Help With Colds? Which Parts Are Fine and Which Are Not

A sauna will not shorten a cold or clear the virus that caused it. The largest trial on the question, published in the Medical Journal of Australia in 2010, sent 157 people with new colds into a Berlin sauna on three consecutive days and found no sustained drop in symptom severity. What the heat reliably delivers is an hour of comfort: a warm airway, thinner mucus, relief from feeling chilled. For an otherwise healthy adult with a normal temperature and mild symptoms, that part is fine. The parts that are not fine are fever, breathlessness, unstable heart disease, and the fluid a session takes from someone who has already spent three days drinking less than usual.

What happened when researchers put people with colds into the heat

Pach and colleagues ran their trial across two winters between November 2007 and April 2009, at a public sauna in Berlin. Every participant sat in the same hot room wearing a winter coat. Eighty breathed hot dry sauna air through a face mask; seventy-seven breathed room-temperature air through an identical mask. Treatment ran three days, follow-up four more.

The result on day two looked promising and then evaporated. Symptom severity fell by 1.0 point in the hot-air group (95% confidence interval −2.0 to −0.1, p = 0.04), and the difference did not hold on days three, five or seven. One finding survived. On day one, 3% of the hot-air group took cold and flu medication against 15% of the controls (p = 0.01). People who felt warmer reached for the packet less often. Three of the 157 coughed because of the mask itself.

Humid heat has been tested more often and for longer. The 2017 Cochrane review by Meenu Singh and colleagues pooled six randomised double-blind trials and 387 participants, all using the same Israeli-built device, the RhinoTherm, which pushes fully saturated air at roughly 43 °C into the nostrils at 40 litres a minute. Those trials disagree with each other, and the split is worth naming. Tyrrell's two 1989 studies and Ophir's 1987 study reported symptom improvement. Macknin's 1990 trial found the placebo group improving more than the treated group, and Forstall's 1994 trial measured nasal resistance 11% better in the placebo arm and 6% worse in the active arm (p < 0.05). Cochrane's verdict is that the evidence shows neither benefit nor harm, at low quality.

That pattern runs through the wider sauna literature. Joy Hussain and Marc Cohen of RMIT University in Melbourne screened the field in 2018 for Evidence-Based Complementary and Alternative Medicine and found 40 clinical studies covering 3,855 participants across 12 countries. Thirteen were randomised controlled trials. Three cleared a low risk-of-bias threshold.

Prevention is a separate question, and the evidence there points the other way, weakly. Edzard Ernst and colleagues at the University of Vienna followed 50 volunteers for six months in 1990, half bathing once or twice a week, and counted 33 cold episodes in the sauna group against 46 among the controls. The gap opened only in the final three months. Mean duration and average severity did not differ. It is one small, unblinded study with self-reported outcomes, and nothing since has replaced it.

Why "sweating out a virus" describes something the body does not do

The phrase survives because real biology sits underneath it, pointing in the right direction and nowhere near far enough.

Ellen Foxman and colleagues at Yale reported in the Proceedings of the National Academy of Sciences in 2015 that most rhinovirus strains replicate better at the 33–35 °C of the nasal cavity than at the 37 °C of the body's core, and that the reason lies with the host rather than the virus. Airway cells mounted a stronger interferon response at the warmer temperature. Akiko Iwasaki, professor of immunobiology at Yale and a co-author, put it this way: "We found that the innate immune response to the rhinovirus is impaired at the lower body temperature compared to the core body temperature."

Sauna air at 80 °C does not deliver 80 °C to the nasal lining. Rafał Podstawski and colleagues, publishing in Frontiers in Public Health in 2024, tracked 22 women through 20 minutes at 80 °C and 14–16% relative humidity. Forehead temperature rose from 36.66 °C to 37.91 °C. Heart rate climbed from 79 to 114 beats a minute. At 120 °C the forehead reached 38.24 °C and the heart rate 121. A 2026 study from the University of Jyväskylä and the Finnish Institute of High Performance Sport, running 50 adults through four ten-minute sessions, recorded a mean core temperature rise of 0.4 °C and a mean heart rate increase of 41.6 beats a minute.

Four-tenths of a degree at one end, a degree and a quarter at the other. The nose warms while a person sits in the room and cools again in the corridor. Sweat is how the body sheds that heat; it is not a channel for expelling anything else.

What the numbers on a sauna's controls actually mean

Hussain and Cohen describe the Finnish standard as 80–100 °C at 10–20% relative humidity. Katriina Kukkonen-Harjula and Kyllikki Kauppinen of the UKK Institute in Tampere set the same band in the International Journal of Circumpolar Health in 2006: 80–90 °C, five to 20 minutes, repeated one to three times.

The hardware matches the literature. Harvia's control units cap the settable room temperature at 110 °C; the C150 unit runs from 40 °C to 110 °C and displays up to 125 °C, and an overheat protector in the sensor box cuts the heater's power permanently if the room becomes dangerously hot, requiring a manual reset once it has cooled. Podstawski's group tested what happens above the normal band and stated the outcome in a single line: "Sauna bathing at a temperature of 80°C can be recommended to women who sporadically use the sauna, whereas exposure to a temperature of 120°C is not advised in this group."

Temperature is not the only dial, and here two sources part company. Conventional guidance treats the wall thermometer as the number that matters. The Jyväskylä team, working with the manufacturer Harvia and placing Vaisala humidity sensors at head height and seat height across the room, found that humidity raises cardiovascular and thermoregulatory strain independently of air temperature, because water already in the air stops sweat evaporating.

Sauna, steam room, and the device the trials actually tested

The two rooms behave differently the moment a person walks in.

| | Finnish sauna | Steam room | RhinoTherm-type device | |---|---|---|---| | Air temperature | 80–100 °C (Hussain and Cohen) | 40–48 °C (Tylö, Harvia and Mr. Steam installation literature) | 43 °C at the nostril (Tyrrell protocol) | | Relative humidity | 10–20% | Near 100% | 100%, fully saturated | | Typical exposure | 5–20 minutes, one to three rounds | Commonly capped at 20 minutes | 20 minutes at 40 litres a minute | | Tested in people with colds | Once, Berlin, 2010 | No direct trial | Six trials, 387 participants | | What the trials found | A day-two blip, gone by day three | Nothing to report | Contradictory; rated low quality | | Hazard while ill | Fluid loss, heat strain, fever | The same strain at a lower air temperature | Minor adverse events in two of six trials |

A steam room at 45 °C sounds like half a sauna, and the airway registers it instantly, which reads as proof that something is working. Abdul Sanu and Ronald Eccles at Cardiff University's Common Cold Centre demonstrated the split cleanly in Rhinology in 2008. A hot fruit drink given to 30 people with colds improved how clear their noses felt and produced no measurable change in nasal airflow. The hot version relieved runny nose, cough, sneezing, sore throat, chilliness and tiredness; the same drink at room temperature relieved only the first three.

The heat changed what people reported. It did not change what the instrument read.

What a session costs in fluid, and what illness has already taken

Podstawski's participants lost 0.14 kg over 20 minutes at 80 °C, and 0.3 kg at 120 °C. The Jyväskylä paper collates comparable figures: 0.21 kg after ten minutes at 80 °C in work by Gravel and colleagues, 0.66 kg across three ten-minute rounds in work by Atencio and colleagues. A kilogram of body mass lost to sweat is roughly a litre of water gone.

Set that against the baseline. The European Food Safety Authority's panel on dietetic products put adequate total water intake at 2.5 litres a day for men and 2.0 litres for women in its 2010 opinion, with fluids supplying 70 to 80 per cent of that — around 2.0 litres of drinks for men and 1.6 for women. EFSA attached a condition that matters here: the figures assume moderate environmental temperature and moderate physical activity. A fever meets neither.

Someone three days into a cold has usually been eating and drinking less than usual, while a raised temperature increases losses through the skin and the breath. Adding half a litre of sweat to that ledger is the part of a sauna visit most likely to make a person feel worse by evening, and it has nothing to do with the virus.

How long the cold lasts, sauna or no sauna

NHS guidance puts recovery from a cold at about one to two weeks, and advises contacting a GP if symptoms have not improved after three weeks or if they suddenly worsen.

Cough runs far longer than almost anyone expects. Mark Ebell, associate professor of epidemiology at the University of Georgia's College of Public Health, and colleagues published a two-part study in Annals of Family Medicine in 2013: a telephone survey of 493 adults in Georgia, paired with a systematic review of 19 observational studies. Respondents expected a cough to last a median of five to seven days, with means between 7.2 and 9.3 days. The published literature put the mean at 17.8 days.

"There is a mismatch in what people believe and reality," Ebell said of the finding. His concern was antibiotic prescribing, and patients returning to the surgery on day five convinced something had gone wrong. The same arithmetic governs sauna claims. A visit on day four of an eleven-day illness is followed by improvement whatever happens in the room, and improvement that arrives on schedule is easy to credit to the last thing tried.

A check before going in, in order

The order matters, because the first failed check ends the sequence.

1. Take a temperature. 38 °C or above means no sauna. The Royal College of Physicians' NEWS2 chart, endorsed by NHS England, scores 36.1 to 38.0 °C as unremarkable and begins adding points at 38.1 °C.
2. Count breaths for a full minute at rest. NEWS2 treats 12 to 20 breaths a minute as normal, 21 to 24 as worth a closer look, and 25 or more as its highest-scoring respiratory alarm. Anything above 20 means the sauna waits.
3. Read the medication list, then the leaflet's cautions section. Clinical summaries of the sauna literature place beta-blockers, nitrates and alcohol in the relative-contraindication tier, along with a tendency to faint on standing.
4. Drink before going in, not only after, and leave alcohol out entirely. It appears on every published list of sauna cautions.
5. Take one short round at the low end of the range. The reviews describe 5 to 20 minutes; a cold is no reason to be at the upper end. Leave at the first hint of light-headedness.
6. Consider the other people in the room. CDC guidance asks anyone with a respiratory infection to stay away from others until symptoms have been improving for at least 24 hours and any fever has gone without fever-reducing medicine.

When the answer is no, and when it means calling someone

Some of these are absolute. Clinical summaries drawn from Hussain and Cohen's review place unstable angina, recent myocardial infarction, severe aortic stenosis, uncontrolled hypertension, and decompensated or ischaemic heart failure in the absolute column. Cardiac arrhythmia, severe valvular disease, alcohol, beta-blockers, nitrates and orthostatic hypotension sit in the relative column. Fever and acute infectious or inflammatory conditions sit among the cautions. A cold running a temperature puts a person on two of those three lists at once.

The signs that call for a clinician come from the instruments used on a hospital ward. NICE's guideline on suspected sepsis, NG51, places a respiratory rate of 25 breaths a minute or more in its high-risk category and 21 to 24 in the moderate-to-high band, alongside a systolic blood pressure of 90 mmHg or below. NEWS2 draws the respiratory bands in the same place. The NHS lists chest pain, difficulty breathing, blood-stained phlegm, a very high temperature with shivering, marked swelling of the glands in the neck or armpits, symptoms that suddenly worsen, and a cold that has not improved after three weeks as reasons to contact a GP, or 111 when the surgery is closed.

None of that shifts because a person feels better for the twenty minutes they spend in a hot room. Pach's participants felt better on day two as well, and by day three the difference had gone.

Questions people ask about saunas and colds

Can a virus be sweated out in a sauna?

No. Sweat carries heat away from the skin; it is not an exit route for viruses. Rhinovirus lives in nasal and airway cells, and sauna air at 80 °C raises core temperature by well under two degrees. The Berlin trial in the Medical Journal of Australia found no sustained benefit.

Can a sauna make a cough go away?

No trial supports that. Mark Ebell's review in Annals of Family Medicine put the average duration of an acute cough at 17.8 days, far longer than most people expect. Heat may soothe the throat for an hour or two, but the cough follows its own timetable regardless.

Does a steam room help with a cold?

Temporarily and inconsistently. The 2017 Cochrane review of heated humidified air pooled six trials and 387 participants, found no effect on viral shedding, and rated the evidence low quality with inconsistent symptom results. Steam rooms run near 100 per cent humidity, which raises heat strain more than the air temperature suggests.

Does sauna heat help congestion?

Subjectively, often; objectively, not much. Sanu and Eccles at Cardiff University's Common Cold Centre found a hot drink improved how clear the nose felt without changing measured nasal airflow. Sauna heat works the same way, easing the sensation of blockage while the swollen lining stays swollen.

Is a sauna useful for a sore throat and cough?

For comfort, sometimes. The Berlin trial found lower medication use on day one among people breathing hot sauna air, and a small symptom drop on day two that vanished by day three. Nothing in it shortened the illness. Anyone with fever, wheeze or chest pain should stay out.

Which symptoms mean someone should skip sauna and seek care?

A temperature of 38 °C or above, breathing faster than 20 breaths a minute, chest pain, confusion, coughing blood, or symptoms that worsen suddenly. The Royal College of Physicians scores a rate of 25 or more as its highest respiratory alert. NHS advice says contact a GP if breathing becomes difficult.