Cold-water dips: Healthy or risky?

Swimming (or just dunking) in cold water is generally safe. But people with heart rhythm disorders should be cautious about this practice. The evidence for the health benefits for cold-water immersion (which allegedly include fat loss and reduced inflammation) is limited. Submerging the face in cold water triggers the diving reflex, which causes the heart to slow down and blood pressure to rise. This response, in addition to an adrenaline surge from cold water on the skin, may trigger an underlying arrhythmia.