Cold Water Shock & Hypothermia

What is Cold Water Shock?

The first state of a sudden / unexpected immersion in water resulting in a sudden gasp for breath followed by rapid breathing.

Cold shock (0-3 mins): Sudden lowering of skin temperature

What happens? 

  • Gasp reflex,
  • Sudden lowering of skin temperature causing sharp increase in blood pressure (risk of heart attack),
  • Hyperventilating (risk of drowning)

What is immersion hypothermia?

Occurs when your core body temperature drops below 35 degrees centigrade. 

Immersion Hypothermia (3-30mins): Body temperature drops below 95º F. (35º C). 

What happens? 

  • Cold symptoms,
  • cramps,
  • possible unconciousness,
  • eventual heart failure or drowning. 

Survival time:

  • At risk in water under 25c
  • UK summer sea temp = 14 – 18c
  • Survival time = 2.5 – 9hrs
  • UK winter sea temp = 6-8c
  • Survival time = 45mins-2hrs 
  • Naked = 26x greater body heat loss
  • Heat loss increased by swimming
  • Best response: H.E.L.P. position, HUDDLE

Possible Signs & Symptoms:

Slurred Speech


Slow breathing

Slow Heart beat


Muscle stiffness / Swim Failure

Cold Skin

Lowered body temperature

Heart failure ( a sudden rise in blood pressure can be fatal for people with pre-existing heart conditions)

How to treat immersion hypothermia as a first aider?

  • Remove from cold environment
  • Check ABCs
  • Prevent further heat loss
  • Gentle handling
  • Slow re-warming
  • Cardiac arrest/ drowning – CPR (traditional vs. drowning)

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