Why Do I Get Nausea After Cold Water Swimming?

Nausea or dizziness brought on after a prolonged swimming period in cold water could be due to several factors.

The most common of these factors is mild hypothermia. In addition, and although this condition can be extremely dangerous if gone unchecked, it is widespread for open water swimmers to experience mild symptoms in the form of sea sickness and/or nausea.

Some other factors that can cause dizziness from swimming, but not just from cold water swimming, are:

  • Motion Sickness
  • Swimmers Ear
  • Low blood sugar levels

All of these factors can potentially play a role in swimmers feeling dizzy after being in cold water.


So let’s dive in and take a look at each in more detail!

Mild Hypothermia & Cold Water

For the sake of simplicity, let’s apply the water temperature band scale where fresh is considered the minimum level in which to swim safely and is considered a cold water swim:

  • Baltic: 0-6 degrees Celsius (32 – 43 Farenheit)
  • Freezing: 6-11 C (43-52 F)
  • Fresh: 12-16 C (53-61 F)

As you enter cold water, there is an initial effect on the body known as cold water shock. Cold receptors close to the surface of the skin sense that there has been rapid cooling, and the body typically responds by increasing heart rate and blood pressure.

Hypothermia begins anywhere from 30 minutes and is caused by the core temperature dropping below 35C (95F). And it is when your body loses heat faster than it can produce it. So to bring your body temperature back up, you’ll need to help it get there.

Your body’s first automatic response to try and warm back up is to trigger shivering. Other symptoms that follow are things such as:

  • Dizziness
  • Nausea
  • Increased heart rate
  • Difficulty sleeping

In the case of cold water swimming, the cooling continues even after you have exited the water. This is when your warming routine becomes essential to recovering your core temperature in a controlled manner.

With more and more scientific research into cold water submersion being done, there is plenty of good advice for raising body temperature from mild hypothermic levels.

How to raise body temperature back safely

Before taking on a cold water swim, it is always a good idea to have someone providing shoreside support who is not swimming. Just in case you are unable to do these things as quickly and require assistance.

The body loses heat through radiated heat, direct contact and wind.

Radiated heat (unprotected skin)
  1. Dry off as soon as you can by removing any wet garments such as wetsuits, thermals and any gloves or booties.
  2. Get changed into warm, dry clothes and put on as many layers as you can. Cashmere clothing is great to insulate with thermally.

Old Wives Tale: Space blankets should not be used for swimmers because there is no heat from the body to be trapped. This is why they work for runners and not for swimmers.

Direct contact (standing on a cold surface)
  1. Ideally, you will have something to stand on that is warmer than the surface below. Simply laying a towel down or using a changing mat will help the process overall.
Wind (wind chill)
  1. Escape the outside wind by seeking shelter so that the body does not continue to lose heat from the wind taking it away. Car’s with heaters on full is a great way to escape wind chill. If that is not an option, find a point out of the breeze until your core temperature recovers.
  2. Having a warm drink to sip on while tucked away from the wind will help warm from within.

Some old trains of thought to avoid are hot showers or baths and even drinking alcohol to warm up. Hot water can negatively affect blood pressure. And alcohol dulls the body’s natural cold shock response designed to keep you safe.

Why do I feel dizzy after swimming?

Dizziness or feeling sea sick is a reasonably common occurrence in open water swimming, but these effects are still possible even in a swimming pool.

In a swimming pool, this motion sickness is caused by too much head movement, disturbing the inner ear balance, which makes you feel unwell. By focusing your vision on the pool floor and only turning your head to breathe, the feeling should disappear.

In wild swimming, there may be choppy water to contend with. This has the potential to cause more frequent sightings, which increases the chance of motion sickness. Another cause could be a pressure change of the inner ear. Simply wearing ear plugs is a way to protect the ear canal.

A more severe case that may cause nausea when swimming is Swimmer’s Ear. This type of ear infection can cause vertigo which affects your balance, amongst other things.

And lastly, there is low blood sugar that can make you feel lightheaded, which stems from dehydration and lack of food intake. The remedies for thee are straightforward and always a good practice when undertaking any form of exercise.

What is Afterdrop and how can it be avoided?

Afterdrop is a term used in cold water and outdoor swimming when you continue to get colder after exiting the water.

It is the onset of mild hypothermia, and the most common symptoms include shivering, nausea or feeling dizzy.

The best way to avoid it is to understand the body’s cold shock response and blood flow by using a slow, methodical warming approach (similar to the method discussed above) to raise the body temperature and avoid hot showers and foil blankets.

Final Thoughts

Knowing that the cause ‘why do I get nausea after cold water swimming’ is mild hypothermia goes a long way to understanding how to recover in the best way.

We looked at several aspects and topics around mild hypothermia, including:

  • Cold shock response
  • How long until symptoms can start to appear
  • The symptoms themselves
  • And also how to warm the body in a controlled manner

In addition, swimmers can experience lightheadedness from motion sickness, Swimmers Ear and even low blood sugar levels.


Vertigo: Its Relation to Wax in the Swimmer’s Ear

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