Cold showers are sometimes touted as a preventative tonic for colds, flu, and infections. However, are these reported benefits just a placebo effect – the power of suggestion, or do cold showers have a direct and measurable effect on our immunity?
Once again, studies show at least some support for the popular wisdom. An experiment in Prague studied the effect of cold water immersions on athletic young men. They immersed them in water at 14 °C (57 °F), three times a week for six weeks. They concluded that the immersions activated the immune system “to a slight extent”.
Among many changes, they saw increased levels of two types of white blood cells: monocytes and lymphocytes. While certain lymphocytes are instrumental in eliminating bacteria, viruses, and toxins, monocytes are indirectly responsible for the engulfing and consuming of pathogens and foreign materials [2,3].
Considering these effects, it’s no surprise that mice exposed to 8 days of brief cold water stress survived significantly longer when exposed to the intracellular parasite, Toxoplasma gondii .
So, cold showers can help keep away the sniffles, but who knows what other nasty virus or pathogen you might also happen to ward off?
 Immune system of cold-exposed and cold-adapted humans.
 Cold stress-induced modulation of cell immunity during acute Toxoplasma Gondii infection in mice.