Cold water shock – the facts The effects of cold water shock are responsible for many of the drownings which occur in the UK every year, as the water temperature in the UK remains cold, even during the summer months. Cold water shock affects our ability to swim and self-rescue. Signs of Cold Water Shock 1. Initial immersion responses – Cold shock response (0–3mins) Immediately after immersion in cold water, rapid cooling of the skin causes a number of instinctive reactions including gasping, hyperventilation, increased blood pressure, and panic. 2. Short term responses – Loss of performance (3–30mins) Following the initial response, the hands, feet, arms and legs start to cool and blood flow is restricted. This causes a decrease in muscle strength and endurance leading to muscle fatigue and reduced control over body movements. If the casualty is unable to get out of the water or use a buoyancy aid, this will ultimately result in drowning. 3. Long term responses – Hypothermia (30mins+) Over time, significant heat loss causes the core body temperature to drop leading to hypothermia which is fatal unless treated effectively.