The claim
“Cold showers mean you get sick less.”
Early. 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.
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
Ben Greenfield's blog
A cold finish to your shower means 29% less sickness.
Gary Brecka's website
Cold water may raise your white blood cell count.
See an example ↗Cold plunge brands
Cold stimulates your white blood cells, and one study substantially lowered upper respiratory infections.
The research found this
The evidence comes from a Dutch trial called the Cool Challenge. In December 2014 researchers recruited 3,018 working adults aged 18 to 65 who did not already take cold showers, and randomly assigned them to finish a normal warm shower with 30 to 90 seconds of cold water or to keep showering as usual.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ The cold groups did it every day through January 2015 and then as they chose for 60 more days. People reported everything through web surveys, including their sick days.
Over 90 days, the cold showerers took 29% fewer days off work for sickness than the usual showerers (incidence rate ratio 0.71, 95% CI 0.56–0.89).Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ The trial also counted days of illness, and those did not differ significantly (0.89, 0.77–1.01). The median person in every group took no sick days and reported two days of illness.
Thirty seconds of cold cut absence as much as 90 seconds did.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ Regular exercise on its own went with a bigger drop in absence (rate ratio 0.65), and the authors' model projected a 54% cut for people who both exercised and took cold showers. About 79% of people completed the 30 days and 64% kept going afterwards.
Other studies of cold and colds are small. In a UK trial of 180 adults, 13 of 90 people who had their feet chilled reported a cold within four to five days, against 5 of 90 controls.Source 2 · Randomized trialAcute cooling of the feet and the onset of common cold symptomsJohnson C, Eccles R. Family Practice, 2005.Read the paper ↗PubMed ↗ Among UK cold-water swimmers followed for 13 weeks, rates of colds did not differ significantly from those of their non-swimming partners or of pool swimmers.Source 3 · Cohort studyHabitual cold-water swimming and upper respiratory tract infectionCollier N, Lomax M, Harper M, et al.. Rhinology journal, 2021.Read the paper ↗PubMed ↗
The dial reads 50°H for four reasons
How the reading adds up
14 + 16 + 18 + 2 = 50°H
EvidenceWhat kind of evidence exists in people?
14/25One large randomized trial tested cold showers against usual showers, with every outcome self-reported by web survey and nobody blinded.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ It counted days of illness directly, and that count did not fall significantly.
ConsistencyHas the finding held up?
16/25The shower evidence comes down to that one trial. Studies of cold-water swimmers point different ways: a 13-week UK comparison found no significant difference in colds across four groups that included the swimmers' own partners, and a Polish survey linked twice-weekly plunging to shorter colds.Source 3 · Cohort studyHabitual cold-water swimming and upper respiratory tract infectionCollier N, Lomax M, Harper M, et al.. Rhinology journal, 2021.Read the paper ↗PubMed ↗Source 4 · Cross-sectional studyInverted “u-shaped” association of cold-water immersion frequency with mental health and upper respiratory tract infection: a cross-sectional studyCzarnecki J, Mokros Ł. Brain, Behavior, & Immunity - Health, 2025.Read the paper ↗PubMed ↗
MagnitudeDoes the claim match the size of the effect?
18/25The claim turns a 29% relative drop in sick days off work into less sickness. Median absence was zero days in every group, and the days people spent ill did not differ significantly.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗
DoseDoes the studied protocol match how people use it?
2/25The trial tested the home habit itself: a normal warm shower finished with 30 to 90 seconds at the coldest setting every day for 30 days. The tap water averaged 10–12°C, and the longest cold finish did no better than the shortest.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗
The claim drifts from the data here
Sick days off work and days of illness can move separately, and this trial measured both. Absence fell while illness did not change significantly, which is the pattern you would see if people felt ill about as often and went to work anyway. Self-reported data can't tell those apart.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗
Recruitment rode on Wim Hof's popularity, and the promotional material listed the benefits people might expect.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ Everyone knew which group they were in and reported their own outcomes, so expectation had room to shape the answers. The trial also ran through an unusually long flu season in 2014–15.
Put it to use
Finish your shower cold if you like how it feels. In the trial, 30 seconds did as much as 90, and regular exercise went with a bigger drop in sick days than the cold showers did.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗
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People also ask
How long should a cold shower be?
In the Dutch trial, finishing with 30 seconds of cold cut sick days off work as much as 60 or 90 seconds did.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ No length of cold shower has been shown to change how often people fall ill.
Do cold showers boost your immune system?
The Dutch trial counted days of illness and found no significant drop. It collected all its data by web survey and took no blood samples, so it says nothing about immune cells.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ The immune studies people cite come from the Wim Hof Method, where the breathing did most of the work.Source 5 · 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 ↗
Are cold showers bad for you?
In the trial, 196 people reported a lingering cold feeling in the body and 257 in the hands or feet, and three of those 257 had Raynaud's. Four had insomnia they linked to evening cold showers.Source 1 · Randomized trialThe Effect of Cold Showering on Health and Work: A Randomized Controlled TrialBuijze GA, Sierevelt IN, van der Heijden BCJM, et al.. PLOS ONE, 2016.Read the paper ↗PubMed ↗ The trial excluded people with severe heart or lung disease.
Check these claims next
56°H
Early
“The Wim Hof Method lets you control your immune system.”
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.
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.
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.
We cited these sources
- 01Buijze GA, Sierevelt IN, van der Heijden BCJM, Dijkgraaf MG, Frings-Dresen MHW. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PLOS ONE. 2016;11(9):e0161749. doi:10.1371/journal.pone.0161749 PMID 27631616
- 02Johnson C, Eccles R. Acute cooling of the feet and the onset of common cold symptoms. Family Practice. 2005;22(6):608-613. doi:10.1093/fampra/cmi072 PMID 16286463
- 03Collier N, Lomax M, Harper M, Tipton M, Massey H. Habitual cold-water swimming and upper respiratory tract infection. Rhinology journal. 2021;59(5):485-487. doi:10.4193/Rhin21.068 PMID 34428265
- 04Czarnecki J, Mokros Ł. Inverted “u-shaped” association of cold-water immersion frequency with mental health and upper respiratory tract infection: a cross-sectional study. Brain, Behavior, & Immunity - Health. 2025;49:101118. doi:10.1016/j.bbih.2025.101118 PMID 41127868
- 05Zwaag 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
- 06Cain T, Brinsley J, Bennett H, Nelson M, Maher C, Singh B. Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis. PLOS ONE. 2025;20(1):e0317615. doi:10.1371/journal.pone.0317615 PMID 39879231