The claim
“Sauna heat kills cancer cells.”
Hot air. In cancer treatment, dedicated devices hold tumor tissue at 40–43°C alongside radiotherapy or chemotherapy. A sauna raises core temperature by well under 2°C, and the one cohort that tracked sauna habits against cancer found no link.
Updated Sep 24, 2026 · 3 studies reviewed
Nothing solid supports it, or the evidence points the other way.
People say it in places like these
FDA warning letter (2022)
A far-infrared sauna seller claimed its sauna helps cancer patients by sending more oxygen to cancerous areas.
See an example ↗Infrared sauna seller (2003)
Far-infrared thermal cancer therapy raises body temperature to kill cancer cells.
FDA warning letter (2009)
A seller claimed its far-infrared sauna dome treated several kinds of cancer.
See an example ↗
The research found this
One study has tracked sauna habits against cancer. In the Kuopio cohort, 2,173 Finnish men aged 42–61 with no history of cancer reported their sauna use and were followed for a median 24.3 years, and 588 of them developed cancer.Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗ Against men who went once a week or less, the hazard ratio for any cancer was 0.92 (95% CI 0.76–1.11) at two or three sessions a week and 0.92 (0.66–1.27) at four or more.
An older Finnish study found no protection either. Among 4,475 men followed for lung cancer from 1964 to 1979, heavy smokers who took saunas more than once a week showed an excess risk (RR 1.7).Source 2 · Cohort studySauna, dust and migration as risk factors in lung cancer among smoking and non‐smoking males in FinlandTenkanen L, Hakulinen T, Hakama M, et al.. International Journal of Cancer, 1985.Read the paper ↗PubMed ↗
Clinical hyperthermia is a hospital procedure. It raises tumor tissue to 40–43°C with multi-antenna applicators and temperature monitoring, and it is given alongside radiotherapy or chemotherapy.Source 3 · ReviewHyperthermia in combined treatment of cancerWust P, Hildebrandt B, Sreenivasa G, et al.. The Lancet Oncology, 2002.Read the paper ↗PubMed ↗ In a randomized phase 3 trial of 341 people with high-risk soft-tissue sarcoma, adding regional hyperthermia to chemotherapy gave a relative hazard of 0.58 for local progression or death, and two-year local progression-free survival reached 76% against 61%.Source 4 · Randomized trialNeo-adjuvant chemotherapy alone or with regional hyperthermia for localised high-risk soft-tissue sarcoma: a randomised phase 3 multicentre studyIssels RD, Lindner LH, Verweij J, et al.. The Lancet Oncology, 2010.Read the paper ↗PubMed ↗
Whole-body hyperthermia goes further. "Extreme" protocols hold core temperature at 41.5–42.0°C for 60 minutes under general anesthesia.Source 5 · ReviewCurrent status of radiant whole-body hyperthermia at temperatures >41.5°C and practical guidelines for the treatment of adults. The German ‘Interdisciplinary Working Group on Hyperthermia’Hildebrandt B, Hegewisch-Becker S, Kerner T, et al.. International Journal of Hyperthermia, 2005.Read the paper ↗PubMed ↗Source 6 · Case seriesAnaesthesiological experiences with whole body hyperthermiaKerner T, Hildebrandt B, Ahlers O, et al.. International Journal of Hyperthermia, 2003.Read the paper ↗PubMed ↗ A 2019 review counted four treatment-related deaths among 350 patients in phase 2 studies and found no phase 3 trials.Source 7 · ReviewWhole-body hyperthermia in combination with systemic therapy in advanced solid malignanciesLassche G, Crezee J, Van Herpen C. Critical Reviews in Oncology/Hematology, 2019.Read the paper ↗PubMed ↗
A sauna works on a much smaller scale. Three 10-minute rounds in a traditional sauna raised core temperature by 0.4°C in a crossover study, and 45 minutes in an infrared cabin left it where it started.Source 8 · Crossover trialComparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalitiesAtencio JK, Reed EL, Wiedenfeld Needham K, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2025.Read the paper ↗PubMed ↗ Longer continuous heat got further: rectal temperature reached 38.50°C after 30 minutes at 73°C in one study, and an infrared cabin at 65°C took it to 38.7°C in 45 minutes in another.Source 9 · Crossover trialHeat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in HumansIguchi M, Littmann AE, Chang SH, et al.. Journal of Athletic Training, 2012.Read the paper ↗PubMed ↗Source 10 · Clinical trialFar‐infrared sauna exposure at 65°C elevates core temperatureJenkins EJ, Killick JA, Grimm SR, et al.. Experimental Physiology, 2026.Read the paper ↗PubMed ↗
The dial reads 93°H for four reasons
How the reading adds up
24 + 20 + 25 + 24 = 93°H
EvidenceWhat kind of evidence exists in people?
24/25We found no study of sauna as a cancer treatment. The only relevant human data come from a Finnish cohort that looked for a link between sauna habits and cancer and found none.Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗
ConsistencyHas the finding held up?
20/25That cohort of 2,173 men found no association with cancer overall or with any of the specific cancers it checked.Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗ An older Finnish cohort reported a relative risk of 1.7 for lung cancer among heavy smokers who took saunas more than once a week.Source 2 · Cohort studySauna, dust and migration as risk factors in lung cancer among smoking and non‐smoking males in FinlandTenkanen L, Hakulinen T, Hakama M, et al.. International Journal of Cancer, 1985.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
25/25The claim describes an effect nobody has measured in sauna users. Clinical whole-body protocols hold core temperature at 41.5–42.0°C for an hour under general anesthesia.Source 5 · ReviewCurrent status of radiant whole-body hyperthermia at temperatures >41.5°C and practical guidelines for the treatment of adults. The German ‘Interdisciplinary Working Group on Hyperthermia’Hildebrandt B, Hegewisch-Becker S, Kerner T, et al.. International Journal of Hyperthermia, 2005.Read the paper ↗PubMed ↗Source 6 · Case seriesAnaesthesiological experiences with whole body hyperthermiaKerner T, Hildebrandt B, Ahlers O, et al.. International Journal of Hyperthermia, 2003.Read the paper ↗PubMed ↗
DoseDoes the studied protocol match how people use it?
24/25Sauna sessions in physiology studies raised core temperature by between 0.0°C and 1.5°C.Source 8 · Crossover trialComparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalitiesAtencio JK, Reed EL, Wiedenfeld Needham K, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2025.Read the paper ↗PubMed ↗Source 11 · Clinical trialThe vascular response to acute sauna heating is similar in young and middle-aged adultsLeach OK, Strong K, Mack GW, et al.. Journal of Applied Physiology, 2024.Read the paper ↗PubMed ↗ No study has tested any sauna dose against cancer.
The claim drifts from the data here
The claim takes an oncology treatment and attaches it to a spa habit. Clinical hyperthermia heats tumor tissue past 40°C with equipment built for the job and pairs it with radiotherapy or chemotherapy, and its phase 3 evidence comes from specific tumors such as soft-tissue sarcoma and pelvic cancers.Source 3 · ReviewHyperthermia in combined treatment of cancerWust P, Hildebrandt B, Sreenivasa G, et al.. The Lancet Oncology, 2002.Read the paper ↗PubMed ↗Source 4 · Randomized trialNeo-adjuvant chemotherapy alone or with regional hyperthermia for localised high-risk soft-tissue sarcoma: a randomised phase 3 multicentre studyIssels RD, Lindner LH, Verweij J, et al.. The Lancet Oncology, 2010.Read the paper ↗PubMed ↗Source 12 · Randomized trialComparison of radiotherapy alone with radiotherapy plus hyperthermia in locally advanced pelvic tumours: a prospective, randomised, multicentre trialvan der Zee J, González D, van Rhoon GC, et al.. The Lancet, 2000.Read the paper ↗PubMed ↗
The Finnish sauna researchers describe core temperature in a sauna as 37–38°C.Source 13 · ReviewFinnish sauna and COVID-19Kunutsor SK, Lavie CJ, Laukkanen J. Le infezioni in medicina, 2021.Read the paper ↗PubMed ↗ At that level no study has shown any effect on cancer. In the one cohort that looked, frequent bathers had a hazard ratio of 0.92 for cancer, and its confidence interval crossed 1.Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗
Put it to use
If you have cancer, ask your oncology team before using a sauna, and treat hyperthermia as a hospital therapy that comes with other treatment. For people without cancer, the Finnish data show sauna habits made no difference to cancer risk either way.Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗
From our sister magazine
Sauna Monthly walks through what the Finnish research means for a home sauna
People also ask
Is sauna good for cancer patients?
No trial has tested it. Clinical hyperthermia is a separate hospital treatment given with radiotherapy or chemotherapy, so people with cancer should ask their oncology team before using a sauna.Source 3 · ReviewHyperthermia in combined treatment of cancerWust P, Hildebrandt B, Sreenivasa G, et al.. The Lancet Oncology, 2002.Read the paper ↗PubMed ↗
Does sauna increase cancer risk?
In 2,173 Finnish men followed for a median 24.3 years, sauna frequency showed no association with cancer (HR 0.92, 95% CI 0.76–1.11, for two or three sessions a week).Source 1 · Cohort studyFinnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort studyLaukkanen JA, Mäkikallio TH, Khan H, et al.. European Journal of Cancer, 2019.Read the paper ↗PubMed ↗
How hot does your body get in a sauna?
Core temperature rose 0.4°C over three 10-minute rounds in one study and reached 38.50°C after 30 minutes at 73°C in another.Source 8 · Crossover trialComparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalitiesAtencio JK, Reed EL, Wiedenfeld Needham K, et al.. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 2025.Read the paper ↗PubMed ↗Source 9 · Crossover trialHeat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in HumansIguchi M, Littmann AE, Chang SH, et al.. Journal of Athletic Training, 2012.Read the paper ↗PubMed ↗ Clinical whole-body hyperthermia holds 41.5–42.0°C for an hour under anesthesia.Source 5 · ReviewCurrent status of radiant whole-body hyperthermia at temperatures >41.5°C and practical guidelines for the treatment of adults. The German ‘Interdisciplinary Working Group on Hyperthermia’Hildebrandt B, Hegewisch-Becker S, Kerner T, et al.. International Journal of Hyperthermia, 2005.Read the paper ↗PubMed ↗
Check these claims next
54°H
Early
“Regular sauna use means you catch fewer colds.”
One 50-person trial from 1990 found fewer colds in regular sauna users, and in the last three of its six months they had about half as many. Nobody has repeated it, and the other support is a Finnish cohort that linked frequent sauna use to less pneumonia.
74°H
Stretched
“Sauna switches on heat shock proteins that slow aging.”
One sauna study found blood heat shock protein 72 up 48.7% on average after 30 minutes at 73°C, and a review of 51 controlled heating studies found no change overall. No study in people has tied heat shock proteins from a sauna to slower aging.
36°H
Likely
“Regular sauna use helps you live longer.”
One Finnish cohort ties frequent sauna use to fewer deaths. With longer follow-up the gap shrank from 40% to about 14%, and it disappeared in the fittest men and in women's heart deaths.
We cited these sources
- 01Laukkanen JA, Mäkikallio TH, Khan H, Laukkanen T, Kauhanen J, Kunutsor SK. Finnish sauna bathing does not increase or decrease the risk of cancer in men: A prospective cohort study. European Journal of Cancer. 2019;121:184-191. doi:10.1016/j.ejca.2019.08.031 PMID 31590079
- 02Tenkanen L, Hakulinen T, Hakama M, Saxén E. Sauna, dust and migration as risk factors in lung cancer among smoking and non‐smoking males in Finland. International Journal of Cancer. 1985;35(5):637-642. doi:10.1002/ijc.2910350511 PMID 3997283
- 03Wust P, Hildebrandt B, Sreenivasa G, Rau B, Gellermann J, Riess H, et al.. Hyperthermia in combined treatment of cancer. The Lancet Oncology. 2002;3(8):487-497. doi:10.1016/S1470-2045(02)00818-5 PMID 12147435
- 04Issels RD, Lindner LH, Verweij J, Wust P, Reichardt P, Schem BC, et al.. Neo-adjuvant chemotherapy alone or with regional hyperthermia for localised high-risk soft-tissue sarcoma: a randomised phase 3 multicentre study. The Lancet Oncology. 2010;11(6):561-570. doi:10.1016/S1470-2045(10)70071-1 PMID 20434400
- 05Hildebrandt B, Hegewisch-Becker S, Kerner T, Nierhaus A, Bakhshandeh-Bath A, Janni W, et al.. Current status of radiant whole-body hyperthermia at temperatures >41.5°C and practical guidelines for the treatment of adults. The German ‘Interdisciplinary Working Group on Hyperthermia’. International Journal of Hyperthermia. 2005;21(2):169-183. doi:10.1080/02656730400003401 PMID 15764358
- 06Kerner T, Hildebrandt B, Ahlers O, Deja M, Riess H, Draeger J, et al.. Anaesthesiological experiences with whole body hyperthermia. International Journal of Hyperthermia. 2003;19(1):1-12. doi:10.1080/02656730210143596 PMID 12519707
- 07Lassche G, Crezee J, Van Herpen C. Whole-body hyperthermia in combination with systemic therapy in advanced solid malignancies. Critical Reviews in Oncology/Hematology. 2019;139:67-74. doi:10.1016/j.critrevonc.2019.04.023 PMID 31112883
- 08Atencio JK, Reed EL, Wiedenfeld Needham K, Lucernoni KM, Comrada LN, Halliwill JR, et al.. Comparison of thermoregulatory, cardiovascular, and immune responses to different passive heat therapy modalities. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2025;329(1):R20-R35. doi:10.1152/ajpregu.00012.2025 PMID 40332494
- 09Iguchi M, Littmann AE, Chang SH, Wester LA, Knipper JS, Shields RK. Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans. Journal of Athletic Training. 2012;47(2):184-190. doi:10.4085/1062-6050-47.2.184 PMID 22488284
- 10Jenkins EJ, Killick JA, Grimm SR, Davies SR, Benson JA, Tremblay JC, et al.. Far‐infrared sauna exposure at 65°C elevates core temperature. Experimental Physiology. 2026:EP094028. doi:10.1113/ep094028 PMID 42533687
- 11Leach OK, Strong K, Mack GW, Gifford JR. The vascular response to acute sauna heating is similar in young and middle-aged adults. Journal of Applied Physiology. 2024;136(3):573-582. doi:10.1152/japplphysiol.00287.2023 PMID 38271083
- 12van der Zee J, González D, van Rhoon GC, van Dijk JD, van Putten WL, Hart AA. Comparison of radiotherapy alone with radiotherapy plus hyperthermia in locally advanced pelvic tumours: a prospective, randomised, multicentre trial. The Lancet. 2000;355(9210):1119-1125. doi:10.1016/S0140-6736(00)02059-6 PMID 10791373
- 13Kunutsor SK, Lavie CJ, Laukkanen J. Finnish sauna and COVID-19. Le infezioni in medicina. 2021;29(1):160-162. PMID 33664187