Cold shock response: myths and realities

How long do we have to wait after eating to swim in the pool or in the sea? What risks do we take if we get into the water just as we finished eating?  People wonder about this each year when summer arrives as this matter raises many doubts, since even specialists disagree about it.

We must clarify first that hydrocution is just a change in temperature and does not have as much to do with food, as is often thought.  Its scientific name is hydrocution and, as we say, it’s the consequence of a sudden change of temperature of our body on contact with cold water.

And it is precisely this sudden thermal change that can produce a cardiovascular reaction with a decrease in heart rate that can make the person suffering from it to feel sick, sometimes even vomiting, dizzy and even lose consciousness, hence the risk.  Although out of the water, this symptoms would be of no further relevance, the risk of drowning is real if it happens to us when in the pool or in the sea.

Things can become more complex in very hot days. Our body temperature is then higher, to this we should add if we just finished eating (with a higher concentration of blood flow in the area of the digestive system) and very cold water.

After long periods of solar exposure or of practising physical exercise you should avoid entering the water suddenly, as your body goes from temperatures higher than 37 degrees to 20 in a question of seconds.

But back to the digestion process, remember that it can last up to four hours, so despite getting into the water, it continues as normal.  It is true that hearty meals take longer to digest.


  • Before entering the water, get wet little by little, especially the head.
  • Enter the water slowly.
  • Never throw yourself into the water.
  • In children it is convenient to wait 1.5 to 2 hours.
  • Children should not stay directly under the sun for a long time. Protect them at all times with hats and especially during and after meals.

If, despite all recommendations, there are symptoms such as dizziness, blurred vision or nausea, you should immediately leave the water and remain in digestive rest for a few hours.  If these symptoms were persistent and did not disappear, it is advisable to visit a health centre or, in extreme cases, notify the emergency services.

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