The claim
“The Wim Hof Method lets you control your immune system.”
Early. Men trained in the method had a smaller inflammatory response to an injected bacterial toxin, and the breathing did most of the work. Cold training alone left that response unchanged in a later trial, and no study has followed practitioners through real infections.
Updated Sep 24, 2026 · 2 studies reviewed
Some human data and a plausible mechanism. It needs better trials before anyone can lean on it.
People say it in places like these
Wim Hof Method website
People who practice the method have a stronger immune response to pathogens than others.
See an example ↗Wim Hof Method science page
Twelve practitioners had anti-inflammatory markers about 200% higher and inflammatory ones about 50% lower.
See an example ↗Wim Hof Method autoimmune page
The method suits autoimmune symptom relief, and followers with conditions like multiple sclerosis report improvements.
See an example ↗
The research found this
The key experiment ran in 2014. Dutch researchers randomly assigned healthy young men to train in the Wim Hof Method or to a control group, and 12 trained and 12 untrained men went through the test day.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ Hof and three instructors led ten days of training. It paired cold exposure with a breathing drill in which the men took about 30 deep, fast breaths and then held their breath for two to three minutes, round after round. Meditation was part of the course as well.
On test day each man received an intravenous dose of bacterial endotoxin, which brings on fever and flu-like symptoms.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ The trained men did the breathing for about three hours with Hof coaching them. Before the injection their adrenaline stood at 1.02 nmol/L, against 0.35 in the untrained men, and it rose to 2.08 during the breathing. Oxygen saturation fell to about 50% at the end of the breath holds.
In the trained men TNF-α came out 53% lower and IL-6 57% lower, and the anti-inflammatory IL-10 ran 194% higher.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ They reported fewer flu-like symptoms and their fevers settled faster. The authors concluded that the breathing appeared to drive most of the adrenaline rise and the dampened immune response.
A 2022 follow-up from the same group tested the parts one at a time. It randomized 48 healthy men to cold exposure training, breathing training, both or neither, and then gave everyone the same endotoxin.Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗ Breathing alone dampened the response. Men who did only the cold training responded much like untrained men, and the combination had the strongest effect.
A 2024 systematic review of nine papers from eight Wim Hof trials found that the most consistent result was a drop in inflammation driven by higher adrenaline.Source 3 · Systematic reviewDoes the Wim Hof Method have a beneficial impact on physiological and psychological outcomes in healthy and non-healthy participants? A systematic reviewAlmahayni O, Hammond L. PLOS ONE, 2024.Read the paper ↗PubMed ↗ Effects on exercise performance and breathing measures were mixed.
The dial reads 56°H for four reasons
How the reading adds up
12 + 10 + 18 + 16 = 56°H
EvidenceWhat kind of evidence exists in people?
12/25Two randomized trials by the same research team injected healthy young men with bacterial endotoxin and tracked the inflammatory response in their blood.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗ Endotoxin is a lab model of infection, and the outcomes were blood markers and flu-like symptoms.
ConsistencyHas the finding held up?
10/25The team repeated the dampened response in 2022 with breathing alone, and a 2024 systematic review named lower inflammation as the most consistent result across Wim Hof trials.Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗Source 3 · Systematic reviewDoes the Wim Hof Method have a beneficial impact on physiological and psychological outcomes in healthy and non-healthy participants? A systematic reviewAlmahayni O, Hammond L. PLOS ONE, 2024.Read the paper ↗PubMed ↗ Most of that work comes from one group, and cold training on its own did not reproduce it.
MagnitudeDoes the claim match the size of the effect?
18/25In the trained men TNF-α came out 53% lower and the anti-inflammatory IL-10 194% higher during experimental endotoxemia.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ The claim turns that into general command over the immune system, which no study has measured.
DoseDoes the studied protocol match how people use it?
16/25Training ran for ten days with Hof and three instructors and included four days of snow and 0–1°C water in Poland.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ On test day the men did the breathing for about three hours with Hof coaching them.
The claim drifts from the data here
Both trials measured how young men's blood responded to one dose of endotoxin.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗ The measured effect was a weaker inflammatory response to that toxin. Popular versions describe a stronger immune system, and no study has checked whether the weaker response helps anyone fight off a real infection.
Cold training on its own left the endotoxin response unchanged in the follow-up, so the cold alone did not reproduce the 2014 result.Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗ The breathing that did the work carries a risk of its own, and it is a poor match for a cold plunge. Hyperventilating before a breath hold delays the urge to breathe while oxygen keeps falling, and in water that can end in a blackout.Source 4 · ReviewThe physiology of survival: Breath‐hold shallow‐water divingBaker AH, Jones A, Mayhew A, et al.. Experimental Physiology, 2026.Read the paper ↗
Put it to use
The breathing drove the measured effect, so if you try the method, do the breathing on dry land and never in or near water.Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗Source 4 · ReviewThe physiology of survival: Breath‐hold shallow‐water divingBaker AH, Jones A, Mayhew A, et al.. Experimental Physiology, 2026.Read the paper ↗ No study shows it will keep you from getting sick.
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People also ask
What did the Wim Hof immune study show?
In a 2014 trial, 12 men trained in the method had lower TNF-α and IL-6 and higher IL-10 after an injection of bacterial endotoxin than 12 untrained men, and they had fewer flu-like symptoms.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗ The authors credited mainly the breathing.
Is it the cold or the breathing in the Wim Hof Method?
Mostly the breathing. In a 2022 trial, breathing alone dampened the response to endotoxin and cold training alone did not change it, although cold made the breathing effect stronger.Source 2 · Randomized trialThe Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot StudyZwaag J, Naaktgeboren R, van Herwaarden AE, et al.. Psychosomatic Medicine, 2022.Read the paper ↗PubMed ↗
Is Wim Hof breathing safe?
Do it on dry land only. Hyperventilating and then holding your breath delays the urge to breathe while oxygen keeps falling, and in water that can end in a blackout.Source 4 · ReviewThe physiology of survival: Breath‐hold shallow‐water divingBaker AH, Jones A, Mayhew A, et al.. Experimental Physiology, 2026.Read the paper ↗ In the 2014 trial, blood oxygen saturation dropped to about 50% at the end of the breath holds.Source 1 · Randomized trialVoluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humansKox M, van Eijk LT, Zwaag J, et al.. Proceedings of the National Academy of Sciences, 2014.Read the paper ↗PubMed ↗
Check these claims next
50°H
Early
“Cold showers mean you get sick less.”
In a trial of 3,018 Dutch adults, people who ended their showers cold took 29% fewer sick days off work. Their days of illness did not differ significantly from those of people who showered as usual, and most people in every group missed no work at all.
62°H
Stretched
“Cold plunges reduce inflammation in your body.”
A 2025 meta-analysis found that inflammatory markers rose right after cold water, and both studies behind that result had people lift weights first. Studies of weeks of regular dips found cytokines unchanged or slightly higher.
18°H
Solid
“The first minute in cold water is the most dangerous part.”
Sudden immersion in cold water sets off a gasp and uncontrollable fast breathing that peak in the first minute, and breathing control usually returns after about a minute. Water-safety researchers attribute about 60% of deaths in the first minutes of immersion to this cold shock.
We cited these sources
- 01Kox M, van Eijk LT, Zwaag J, van den Wildenberg J, Sweep FCGJ, van der Hoeven JG, et al.. Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans. Proceedings of the National Academy of Sciences. 2014;111(20):7379-7384. doi:10.1073/pnas.1322174111 PMID 24799686
- 02Zwaag J, Naaktgeboren R, van Herwaarden AE, Pickkers P, Kox M. The Effects of Cold Exposure Training and a Breathing Exercise on the Inflammatory Response in Humans: A Pilot Study. Psychosomatic Medicine. 2022;84(4):457-467. doi:10.1097/PSY.0000000000001065 PMID 35213875
- 03Almahayni O, Hammond L. Does the Wim Hof Method have a beneficial impact on physiological and psychological outcomes in healthy and non-healthy participants? A systematic review. PLOS ONE. 2024;19(3):e0286933. doi:10.1371/journal.pone.0286933 PMID 38478473
- 04Baker AH, Jones A, Mayhew A, McAvoy C, Macleod R, Montgomery H, et al.. The physiology of survival: Breath‐hold shallow‐water diving. Experimental Physiology. 2026;111(5):2403-2410. doi:10.1113/EP093322