The claim

“Sauna lowers inflammation in your body.”

Stretched. Finnish men who took the most saunas had slightly lower levels of the inflammation marker CRP, and the link was weak. Trials that heated people for weeks found no change in CRP, and one session nudges some inflammatory signals up.

Updated Sep 24, 2026 · 1 study reviewed

The claim pulls a real finding well past what the study showed.

People say it in places like these

Bryan Johnson's blog
Regular sauna use lowers inflammation by as much as 31.5%.
See an example ↗
Infrared sauna sellers
Infrared heat helps reduce inflammation.

The research found this

The claim starts with the Finnish KIHD study. In 2,084 men without inflammatory disease, average CRP was 2.41 in weekly bathers and 1.65 in men who went four to seven times a week.Source 1 · Cross-sectional studySauna bathing and systemic inflammationLaukkanen JA, Laukkanen T. European Journal of Epidemiology, 2018.Read the paper ↗PubMed ↗ The published letter gives the unit as mmol/L, although CRP is normally reported in mg/L.

A second analysis of the same men took account of age, body mass index, smoking, physical activity and other factors. CRP was 0.84 mg/L lower in the four-to-seven group than in weekly bathers at the start and 1.66 mg/L lower 11 years later. Sauna frequency and CRP still correlated only weakly (r = −0.07).Source 2 · Cohort studyLongitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort studyKunutsor SK, Laukkanen T, Laukkanen JA. Annals of Medicine, 2018.Read the paper ↗PubMed ↗

The heating trials found no change in CRP. A 2025 meta-analysis pooled 51 controlled studies and saw no shift after one session or many, and a pooled analysis of 20 randomized trials that heated people for at least a week agreed.Source 3 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗ In a small randomized trial of 15 men, four weeks of 30-minute saunas after cycling left CRP where it started.Source 5 · Randomized trialNo effects of a 4-week post-exercise sauna bathing on targeted gut microbiota and intestinal barrier function, and hsCRP in healthy men: a pilot randomized controlled trialKarolkiewicz J, Nieman DC, Cisoń T, et al.. BMC Sports Science, Medicine and Rehabilitation, 2022.Read the paper ↗PubMed ↗

One session can nudge some inflammatory signals up. In adults averaging 66, the inflammatory signal IL-6 rose 0.92 pg/mL about an hour after two 10-minute rounds at 80°C, and one round alone didn't move it. CRP stayed flat after both.Source 6 · Crossover trialImpact of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults: A crossover studyBehzadi P, Gravel H, Neagoe PE, et al.. Complementary Therapies in Medicine, 2020.Read the paper ↗PubMed ↗ In a head-to-head test only hot water raised IL-6, and medical whole-body heating for depression tripled it.Source 7 · 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 8 · Clinical trialThe antidepressant effect of whole-body hyperthermia is associated with the classical interleukin-6 signaling pathwayMac Giollabhui N, Lowry CA, Nyer M, et al.. Brain, Behavior, and Immunity, 2024.Read the paper ↗PubMed ↗ After a 30-minute sauna, only 2 of 37 cytokines (immune signaling molecules) changed, and both fell.Source 9 · Clinical trialAcute Finnish sauna heat exposure induces stronger immune cell than cytokine responsesHeinonen IH, Koivula T, Hollmén M, et al.. Temperature, 2026.Read the paper ↗PubMed ↗

One small trial in heart failure reported lower CRP and other inflammatory markers after two weeks of daily 10-minute hot-spring baths at 40°C.Source 10 · Randomized trialHyperthermia by bathing in a hot spring improves cardiovascular functions and reduces the production of inflammatory cytokines in patients with chronic heart failureOyama JI, Kudo Y, Maeda T, et al.. Heart and Vessels, 2013.Read the paper ↗PubMed ↗

The dial reads 64°H for four reasons

How the reading adds up

20 + 22 + 16 + 6 = 64°H

EvidenceWhat kind of human evidence exists?
20/25
Researchers observed more than 2,000 Finnish men and found lower CRP in those who took more saunas.Source 1 · Cross-sectional studySauna bathing and systemic inflammationLaukkanen JA, Laukkanen T. European Journal of Epidemiology, 2018.Read the paper ↗PubMed ↗Source 2 · Cohort studyLongitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort studyKunutsor SK, Laukkanen T, Laukkanen JA. Annals of Medicine, 2018.Read the paper ↗PubMed ↗ When heating trials were pooled, CRP didn't change.Source 3 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗
ConsistencyHave other studies found the same thing?
22/25
The trials contradict the Finnish data. Pooled randomized trials found no effect on CRP, and after one sauna session CRP stayed flat as IL-6 edged up.Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗Source 6 · Crossover trialImpact of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults: A crossover studyBehzadi P, Gravel H, Neagoe PE, et al.. Complementary Therapies in Medicine, 2020.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
16/25
The correlation between sauna frequency and CRP was close to zero (r = −0.07).Source 2 · Cohort studyLongitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort studyKunutsor SK, Laukkanen T, Laukkanen JA. Annals of Medicine, 2018.Read the paper ↗PubMed ↗ At the start of the study, men who went four to seven times a week averaged 0.84 mg/L less CRP than weekly bathers.
DoseDoes the studied dose match how people use it?
6/25
The Finnish men took ordinary saunas at about 79°C for 14 minutes around twice a week.Source 11 · Cohort studyAssociation Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality EventsLaukkanen T, Khan H, Zaccardi F, et al.. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗ Trials of repeated heating over weeks still found no change in CRP.Source 3 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗

The claim drifts from the data here

A weak link in Finnish men becomes a promise that heat lowers inflammation. The frequent bathers also smoked less and were fitter than weekly bathers.Source 2 · Cohort studyLongitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort studyKunutsor SK, Laukkanen T, Laukkanen JA. Annals of Medicine, 2018.Read the paper ↗PubMed ↗Source 11 · Cohort studyAssociation Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality EventsLaukkanen T, Khan H, Zaccardi F, et al.. JAMA Internal Medicine, 2015.Read the paper ↗PubMed ↗

When researchers heated people for weeks and measured CRP, it didn't move.Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗Source 3 · Meta-analysisHeat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysisPrice BS, Lucas SJE, Akerman AP, et al.. Experimental Physiology, 2025.Read the paper ↗PubMed ↗ In the hour after two sauna rounds, the inflammatory marker IL-6 rose slightly.Source 6 · Crossover trialImpact of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults: A crossover studyBehzadi P, Gravel H, Neagoe PE, et al.. Complementary Therapies in Medicine, 2020.Read the paper ↗PubMed ↗

Put it to use

A sauna is a poor bet for lowering CRP, since heating trials found no change.Source 4 · Meta-analysisNon-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trialsHamaya R, Joyama Y, Miyata T, et al.. American Journal of Preventive Cardiology, 2025.Read the paper ↗PubMed ↗ If you want a measurable effect, a small drop in blood pressure has better support.

From our sister magazine

Sauna Monthly walks buyers through the Finnish sauna research

Sauna Monthly · Guide

Sauna Monthly turns the Finnish research into a buying brief

The piece walks through the long Finnish study and what it means for a home sauna.

Read it on Sauna Monthly

Sauna Monthly · Shop

These outdoor saunas reach Finnish temperatures

Sauna Monthly compares barrels and cabins that run hot-rock heaters.

Read it on Sauna Monthly

Check these claims next

62°H

Stretched

Cold

“Cold plunges reduce inflammation in your body.”

A 2025 pooled analysis of 11 studies found that inflammation markers rose right after cold water, and the two studies behind that result both had people lift weights first. When people took regular dips for weeks, blood markers of inflammation stayed flat or rose slightly.

54°H

Unsettled

Heat

“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. It stands alone, and the other support comes from a Finnish study that linked frequent sauna use to less pneumonia.

36°H

Likely

Heat

“Using a sauna four to seven times a week halves your risk of dying from heart disease.”

In a Finnish study that tracked men for about 20 years, those who took four to seven saunas a week died of heart disease at about half the rate of once-a-week bathers. Later analyses of the same men found a smaller difference. The link didn't show up in the fittest men, and women who went two or three times a week did no better than women who went once.

We cited these sources

01Laukkanen JA, Laukkanen T. Sauna bathing and systemic inflammation. European Journal of Epidemiology. 2018;33(3):351-353. doi:10.1007/s10654-017-0335-y PMID 29209938
02Kunutsor SK, Laukkanen T, Laukkanen JA. Longitudinal associations of sauna bathing with inflammation and oxidative stress: the KIHD prospective cohort study. Annals of Medicine. 2018;50(5):437-442. doi:10.1080/07853890.2018.1489143 PMID 29897261
03Price BS, Lucas SJE, Akerman AP, Gilworth RE, Lucas RAI. Heat thermotherapy to improve cardiovascular function and cardiometabolic health: A systematic review and meta‐analysis. Experimental Physiology. 2025:EP092404. doi:10.1113/EP092404 PMID 41166412
04Hamaya R, Joyama Y, Miyata T, Fuse SI, Yamane N, Maruyama N, et al.. Non-acute effects of passive heating interventions on cardiometabolic risk and vascular health: systematic review and meta-analysis of randomized controlled trials. American Journal of Preventive Cardiology. 2025;23:101082. doi:10.1016/j.ajpc.2025.101082 PMID 41049507
05Karolkiewicz J, Nieman DC, Cisoń T, Szurkowska J, Gałęcka M, Sitkowski D, et al.. No effects of a 4-week post-exercise sauna bathing on targeted gut microbiota and intestinal barrier function, and hsCRP in healthy men: a pilot randomized controlled trial. BMC Sports Science, Medicine and Rehabilitation. 2022;14(1):107. doi:10.1186/s13102-022-00497-z PMID 35710395
06Behzadi P, Gravel H, Neagoe PE, Barry H, Sirois MG, Gagnon D. Impact of Finnish sauna bathing on circulating markers of inflammation in healthy middle-aged and older adults: A crossover study. Complementary Therapies in Medicine. 2020;52:102486. doi:10.1016/j.ctim.2020.102486 PMID 32951736
07Atencio 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
08Mac Giollabhui N, Lowry CA, Nyer M, Foster SL, Liu RT, Smith DG, et al.. The antidepressant effect of whole-body hyperthermia is associated with the classical interleukin-6 signaling pathway. Brain, Behavior, and Immunity. 2024;119:801-806. doi:10.1016/j.bbi.2024.04.040 PMID 39848840
09Heinonen IH, Koivula T, Hollmén M, Immonen J, Kunutsor SK, Jalkanen S, et al.. Acute Finnish sauna heat exposure induces stronger immune cell than cytokine responses. Temperature. 2026;13(2):186-199. doi:10.1080/23328940.2026.2645467 PMID 42282896
10Oyama JI, Kudo Y, Maeda T, Node K, Makino N. Hyperthermia by bathing in a hot spring improves cardiovascular functions and reduces the production of inflammatory cytokines in patients with chronic heart failure. Heart and Vessels. 2013;28(2):173-178. doi:10.1007/s00380-011-0220-7 PMID 22231540
11Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine. 2015;175(4):542-548. doi:10.1001/jamainternmed.2014.8187 PMID 25705824

People say it in places like these

The research found this

The dial reads 64°H for four reasons

EvidenceWhat kind of human evidence exists?

ConsistencyHave other studies found the same thing?

MagnitudeDoes the claim match the size of the effect?

DoseDoes the studied dose match how people use it?