Winter swimmers report fewer common colds but no reduction in influenza.
Winter swimmers report fewer common colds than non-swimmers, but they do not appear to experience less influenza. A 2026 pilot study surveyed 94 adults in Western Poland about winter-swimming habits, physical activity, influenza, common colds, and infection-related medication use. Sixty-seven participants practiced winter swimming and 27 did not.
Winter swimmers reported a significantly lower occurrence of common colds than non-swimmers. The association also differed across categories of swimming frequency. However, the groups did not differ significantly in reported influenza incidence or influenza symptom severity.
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The findings are exploratory. This was a small, cross-sectional survey rather than a randomized or longitudinal trial. Illnesses were recalled rather than confirmed by medical records or laboratory testing, and winter swimmers were more physically active than controls. Although the authors did not find physical activity independently associated with the infection outcomes, residual healthy-user and lifestyle differences remain possible.
The study supports further research into cold exposure and mild respiratory illness, but it does not establish that winter swimming prevents colds and provides no evidence of protection against influenza.