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Sauna Hype°H

The claim

“You can sweat out toxins in a sauna.”

Stretched. Sweat carries traces of metals and chemicals, and the studies that report large amounts relied on sweat people scraped off their own skin. When researchers collected sweat carefully, a session's worth held a small fraction of what the kidneys clear in a day.

Updated Sep 24, 2026 · 2 studies reviewed

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

People say it in places like these

  • Infrared sauna sellers

    A 2023 study found infrared sauna sweat held more toxic metals than sweat from exercise or a steam sauna.

  • Ben Greenfield's blog

    Sauna sweat clears heavy metals and PCBs out of your body.

    See an example ↗

  • Research abstracts

    Induced sweating could be a way to eliminate toxic elements that build up in the body.

    See an example ↗

The research found this

A sauna session produces about half a liter of sweat. Among 674 first-time users, two 10-minute rounds at 90°C took off an average of 0.37 kg in women and 0.50 kg in men. In another study, where the same volunteers tried more than one kind of heat, three 10-minute rounds in a traditional sauna produced 0.66 kg.Source 1 · Clinical trialSauna-Induced Body Mass Loss in Young Sedentary Women and MenPodstawski R, Boraczyński T, Boraczyński M, et al.. The Scientific World Journal, 2014.Read the paper ↗PubMed ↗Source 2 · 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 ↗ The kidneys pass 1–2 L of urine every day.Source 3 · BookDietary Reference Intakes for Water, Potassium, Sodium, Chloride, and SulfateInstitute of Medicine. National Academies Press, 2005.Read the paper ↗

Most of the papers that report large amounts of toxic metals and chemicals in sweat come from one project. Its authors called the series BUS because it compared sweat with blood and urine, and its six papers all describe the same 20 people. Ten of them were patients recruited from the lead author's clinical practice.Source 4 · Cross-sectional studyBlood, Urine, and Sweat (BUS) Study: Monitoring and Elimination of Bioaccumulated Toxic ElementsGenuis SJ, Birkholz D, Rodushkin I, et al.. Archives of Environmental Contamination and Toxicology, 2011.Read the paper ↗PubMed ↗Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗ Each person collected at least 100 mL of sweat from anywhere on the body, either by holding a glass jar to the skin or by scraping sweat off with a stainless-steel spatula. The instructions set no time for how long people should sweat before collecting.Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗

Skin contaminates the sample too. Sweat scraped off the skin carried 4 to 10 times more fat than clean sweat in one study.Source 6 · Clinical trialFree fatty acids and sterols in human eccrine sweatTakemura T, Wertz P, Sato K. British Journal of Dermatology, 1989.Read the paper ↗PubMed ↗ Researchers in another study cleaned the skin meticulously before fitting arm bags, and mineral readings still started high, then fell 26–76% in later samples.Source 7 · Clinical trialSurface contamination artificially elevates initial sweat mineral concentrationsEly MR, Kenefick RW, Cheuvront SN, et al.. Journal of Applied Physiology, 2011.Read the paper ↗PubMed ↗

Studies that controlled the collection found much less. Twenty-four healthy people sweated into arm bags in a hot chamber, and their sweat lead averaged 5.2 µg/L. That came to about a quarter of the concentration in their urine.Source 8 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗ When two volunteers swallowed lead, it rose in their blood and urine and stayed flat in their sweat.Source 9 · Clinical trialSweat lead levels in persons with high blood lead levels: experimental elevation of blood lead by ingestion of lead chlorideOmokhodion FO, Crockford GW. Science of The Total Environment, 1991.Read the paper ↗PubMed ↗

The body clears the plastics chemical BPA through urine. A swallowed dose is recovered completely there, and half of it is gone in under 6 hours.Source 10 · Clinical trialMetabolism and Kinetics of Bisphenol A in Humans at Low Doses Following Oral AdministrationVölkel W, Colnot T, Csanády GA, et al.. Chemical Research in Toxicology, 2002.Read the paper ↗PubMed ↗ Sweat patches worn for a week found no BPA above background even when the wearer's urine held 195 ng/mL.Source 11 · Cross-sectional studyA Preliminary Study of Biomonitoring for Bisphenol-A in Human SweatPorucznik CA, Cox KJ, Wilkins DG, et al.. Journal of Analytical Toxicology, 2015.Read the paper ↗PubMed ↗ A 2019 review of sweat physiology concludes that sweat's part in removing toxic substances is minor next to the kidneys and gut. It also cites studies that tracked labeled doses of heavy metals through the body, and in those studies feces were the main way out.Source 12 · ReviewPhysiology of sweat gland function: The roles of sweating and sweat composition in human healthBaker LB. Temperature, 2019.Read the paper ↗PubMed ↗

The dial reads 68°H for four reasons

How the reading adds up

18 + 20 + 22 + 8 = 68°H

  1. EvidenceWhat kind of human evidence exists?

    18/25

    Small studies have found metals and chemicals in sweat, and no study has shown that sweating lowers the amount stored in the body. The best-known series took one self-collected sample from each of 20 people.Source 4 · Cross-sectional studyBlood, Urine, and Sweat (BUS) Study: Monitoring and Elimination of Bioaccumulated Toxic ElementsGenuis SJ, Birkholz D, Rodushkin I, et al.. Archives of Environmental Contamination and Toxicology, 2011.Read the paper ↗PubMed ↗Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗

  2. ConsistencyHave other studies found the same thing?

    20/25

    Which way the numbers point depends on how the sweat was collected. A 2012 review lists lead in the self-collected BUS sweat at 31 µg/L against 1.8 µg/L in urine. Sweat caught in arm bags from 24 people ran at about a quarter of their urine level.Source 13 · Systematic reviewArsenic, Cadmium, Lead, and Mercury in Sweat: A Systematic ReviewSears ME, Kerr KJ, Bray RI. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗Source 8 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗

  3. MagnitudeDoes the claim match the size of the effect?

    22/25

    Going by the arm-bag numbers, half a liter of sweat carries about 8% of the lead that a day's urine removes.Source 8 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗Source 3 · BookDietary Reference Intakes for Water, Potassium, Sodium, Chloride, and SulfateInstitute of Medicine. National Academies Press, 2005.Read the paper ↗ Swallowed BPA comes out completely in urine, and sweat patches found none above background even when urine levels were high.Source 10 · Clinical trialMetabolism and Kinetics of Bisphenol A in Humans at Low Doses Following Oral AdministrationVölkel W, Colnot T, Csanády GA, et al.. Chemical Research in Toxicology, 2002.Read the paper ↗PubMed ↗Source 11 · Cross-sectional studyA Preliminary Study of Biomonitoring for Bisphenol-A in Human SweatPorucznik CA, Cox KJ, Wilkins DG, et al.. Journal of Analytical Toxicology, 2015.Read the paper ↗PubMed ↗

  4. DoseDoes the studied dose match how people use it?

    8/25

    The sweat studies used ordinary heat, and it ranged from infrared and steam saunas to 20 minutes in a sauna cabinet at 45°C.Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗Source 14 · Crossover trialExcretion of Ni, Pb, Cu, As, and Hg in Sweat under Two Sweating ConditionsKuan WH, Chen YL, Liu CL. International Journal of Environmental Research and Public Health, 2022.Read the paper ↗PubMed ↗ Clinical detox programs have prescribed 2–5 hours of heavy sweating a day.Source 12 · ReviewPhysiology of sweat gland function: The roles of sweating and sweat composition in human healthBaker LB. Temperature, 2019.Read the paper ↗PubMed ↗

The claim drifts from the data here

Most detox copy quotes concentrations in sweat and leaves out how much sweat there is. A session makes about half a liter, and the kidneys pass 1–2 L of urine every day.Source 1 · Clinical trialSauna-Induced Body Mass Loss in Young Sedentary Women and MenPodstawski R, Boraczyński T, Boraczyński M, et al.. The Scientific World Journal, 2014.Read the paper ↗PubMed ↗Source 3 · BookDietary Reference Intakes for Water, Potassium, Sodium, Chloride, and SulfateInstitute of Medicine. National Academies Press, 2005.Read the paper ↗ In the same people, sweat lead ran at a quarter of the urine level.Source 8 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗

The BUS figures don't square with how much BPA people take in. By our arithmetic from the project's BPA table, half a liter of sweat would hold about 9.7 µg of BPA. Researchers who estimated intake from urine put the 2005–06 US median at about 2.4 µg a day for a 70 kg adult.Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗Source 15 · DatasetDaily intake of bisphenol A and potential sources of exposure: 2005–2006 National Health and Nutrition Examination SurveyLaKind JS, Naiman DQ. Journal of Exposure Science & Environmental Epidemiology, 2011.Read the paper ↗PubMed ↗ One session would then remove more BPA than a typical American takes in each day, and that clashes with dosing studies that recover the whole dose in urine.Source 10 · Clinical trialMetabolism and Kinetics of Bisphenol A in Humans at Low Doses Following Oral AdministrationVölkel W, Colnot T, Csanády GA, et al.. Chemical Research in Toxicology, 2002.Read the paper ↗PubMed ↗ The BUS authors themselves wrote that urine remains an important route because people pass much more urine than sweat in a day.Source 5 · Cross-sectional studyHuman Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) StudyGenuis SJ, Beesoon S, Birkholz D, et al.. Journal of Environmental and Public Health, 2012.Read the paper ↗PubMed ↗

For pollutants that persist in the body, such as PCBs, the only published estimate of what sweat removes against what people take in comes from a 2018 letter.Source 16 · ReviewCan POPs be substantially popped out through sweat?Imbeault P, Ravanelli N, Chevrier J. Environment International, 2018.Read the paper ↗PubMed ↗ We couldn't read the full text, so we've left the figures out. The infrared version of this claim attaches a toxin percentage to sweat with no study behind it.

Put it to use

Use the sauna for the heat, and drink water to replace what you sweat. If a clinic sells sweating as a way to clear metals or chemicals, ask what it measured. The published data find traces in sweat, and the body clears most of these substances through urine and feces.Source 12 · ReviewPhysiology of sweat gland function: The roles of sweating and sweat composition in human healthBaker LB. Temperature, 2019.Read the paper ↗PubMed ↗

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People also ask

How much do you sweat in a sauna?

About half a liter in a typical session. Women trying a sauna for the first time lost an average of 0.37 kg over two 10-minute rounds at 90°C, and men lost 0.50 kg. Three 10-minute rounds in a traditional sauna produced 0.66 kg in another study.Source 1 · Clinical trialSauna-Induced Body Mass Loss in Young Sedentary Women and MenPodstawski R, Boraczyński T, Boraczyński M, et al.. The Scientific World Journal, 2014.Read the paper ↗PubMed ↗Source 2 · 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 ↗

Do saunas remove heavy metals?

Only in trace amounts. When 24 people sweated in a hot chamber, their sweat held lead at about a quarter of their urine concentration. A 2019 review names feces as the main exit for heavy metals.Source 8 · Clinical trialLead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1Omokhodion F, Crockford G. The Science of The Total Environment, 1991.Read the paper ↗PubMed ↗Source 12 · ReviewPhysiology of sweat gland function: The roles of sweating and sweat composition in human healthBaker LB. Temperature, 2019.Read the paper ↗PubMed ↗

Can you sweat out PFAS?

Not by the evidence so far. The BUS project's own PFAS paper found "minimal to none" of the three compounds it tracked in sweat, and it concluded that sweating does not appear to clear them.Source 17 · Cross-sectional studyBiomonitoring and Elimination of Perfluorinated Compounds and Polychlorinated Biphenyls through Perspiration: Blood, Urine, and Sweat StudyGenuis SJ, Beesoon S, Birkholz D. ISRN Toxicology, 2013.Read the paper ↗PubMed ↗

Check these claims next

96°H

Hot air

Heat

“Infrared sauna sweat is 20% toxins, where a normal sauna's is only 3%.”

No study backs these percentages, and measured sweat is at least 99% water. An infrared sauna seller was already crediting them to an unnamed American study in 2002.

92°H

Hot air

Heat

“You can sweat out a hangover in a sauna.”

The liver removes about 90% of alcohol, and sweat carries it at about the same concentration as blood, so a sauna barely touches the total. Finnish sauna researchers link the hangover phase to heart rhythm risk.

62°H

Stretched

Heat

“Sauna helps you lose weight.”

The half kilogram or so you lose in a session is sweat, and it comes back once you drink and eat. In a randomized trial that measured fat, a 15-minute sauna after exercise added no fat loss beyond the exercise itself.

We cited these sources

  1. 01Podstawski R, Boraczyński T, Boraczyński M, Choszcz D, Mańkowski S, Markowski P. Sauna-Induced Body Mass Loss in Young Sedentary Women and Men. The Scientific World Journal. 2014;2014:307421. doi:10.1155/2014/307421 PMID 25614882
  2. 02Atencio 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
  3. 03Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies Press. 2005. doi:10.17226/10925
  4. 04Genuis SJ, Birkholz D, Rodushkin I, Beesoon S. Blood, Urine, and Sweat (BUS) Study: Monitoring and Elimination of Bioaccumulated Toxic Elements. Archives of Environmental Contamination and Toxicology. 2011;61(2):344-357. doi:10.1007/s00244-010-9611-5 PMID 21057782
  5. 05Genuis SJ, Beesoon S, Birkholz D, Lobo RA. Human Excretion of Bisphenol A: Blood, Urine, and Sweat (BUS) Study. Journal of Environmental and Public Health. 2012;2012:185731. doi:10.1155/2012/185731 PMID 22253637
  6. 06Takemura T, Wertz P, Sato K. Free fatty acids and sterols in human eccrine sweat. British Journal of Dermatology. 1989;120(1):43-47. doi:10.1111/j.1365-2133.1989.tb07764.x PMID 2638916
  7. 07Ely MR, Kenefick RW, Cheuvront SN, Chinevere TD, Lacher CP, Lukaski HC, et al.. Surface contamination artificially elevates initial sweat mineral concentrations. Journal of Applied Physiology. 2011;110(6):1534-1540. doi:10.1152/japplphysiol.01437.2010 PMID 21512152
  8. 08Omokhodion F, Crockford G. Lead in sweat and its relationship to salivary and urinary levels in normal healthy subjects1. The Science of The Total Environment. 1991;103(2–3):113-122. doi:10.1016/0048-9697(91)90137-4 PMID 1882227
  9. 09Omokhodion FO, Crockford GW. Sweat lead levels in persons with high blood lead levels: experimental elevation of blood lead by ingestion of lead chloride. Science of The Total Environment. 1991;108(3):235-242. doi:10.1016/0048-9697(91)90360-q PMID 1754878
  10. 10Völkel W, Colnot T, Csanády GA, Filser JG, Dekant W. Metabolism and Kinetics of Bisphenol A in Humans at Low Doses Following Oral Administration. Chemical Research in Toxicology. 2002;15(10):1281-1287. doi:10.1021/tx025548t PMID 12387626
  11. 11Porucznik CA, Cox KJ, Wilkins DG, Anderson DJ, Bailey NM, Szczotka KM, et al.. A Preliminary Study of Biomonitoring for Bisphenol-A in Human Sweat. Journal of Analytical Toxicology. 2015;39(7):562-566. doi:10.1093/jat/bkv055 PMID 26013102
  12. 12Baker LB. Physiology of sweat gland function: The roles of sweating and sweat composition in human health. Temperature. 2019;6(3):211-259. doi:10.1080/23328940.2019.1632145 PMID 31608304
  13. 13Sears ME, Kerr KJ, Bray RI. Arsenic, Cadmium, Lead, and Mercury in Sweat: A Systematic Review. Journal of Environmental and Public Health. 2012;2012:184745. doi:10.1155/2012/184745 PMID 22505948
  14. 14Kuan WH, Chen YL, Liu CL. Excretion of Ni, Pb, Cu, As, and Hg in Sweat under Two Sweating Conditions. International Journal of Environmental Research and Public Health. 2022;19(7):4323. doi:10.3390/ijerph19074323 PMID 35410004
  15. 15LaKind JS, Naiman DQ. Daily intake of bisphenol A and potential sources of exposure: 2005–2006 National Health and Nutrition Examination Survey. Journal of Exposure Science & Environmental Epidemiology. 2011;21(3):272-279. doi:10.1038/jes.2010.9 PMID 20237498
  16. 16Imbeault P, Ravanelli N, Chevrier J. Can POPs be substantially popped out through sweat?. Environment International. 2018;111:131-132. doi:10.1016/j.envint.2017.11.023 PMID 29197670
  17. 17Genuis SJ, Beesoon S, Birkholz D. Biomonitoring and Elimination of Perfluorinated Compounds and Polychlorinated Biphenyls through Perspiration: Blood, Urine, and Sweat Study. ISRN Toxicology. 2013;2013:483832. doi:10.1155/2013/483832 PMID 24083032