Contrast Shower (Hot/Cold) for Immune Function

Research on contrast showers and immune function is extremely limited, and the one available study identified here does not directly examine immune outcomes from hot and cold water alternation at all. Instead, it investigated microbial contamination risks in building plumbing systems during periods of disuse, finding that stagnant water in showers can harbor potentially harmful bacteria such as Legionella species and non-tuberculous mycobacteria, with infection risk modeling suggesting meaningful exposure concerns if water lines are not regularly flushed. This study is observational and epidemiological in nature, and its findings are neutral in direction with respect to any therapeutic use of showering. Readers interested in the immunological effects of contrast hydrotherapy should be aware that the current linked evidence base does not address that question, and broader literature searches would be needed to evaluate what, if any, research exists on that specific topic.