Jumping into some crisp, refreshing water may look tempting – but is it worth the risk? And just how cold is too cold? We’ll go over when a dip in cool water is a worthwhile choice and when it should be avoided.
Can You Get Ill from Swimming in Cold Water? Swimming in cold water will not cause illness on its own, but there are risks you should be aware of prior to taking the plunge. For example, one of the biggest risks of swimming in cold water is hypothermia. You could also risk getting cold water shock, especially if you dive straight in. There is also the potential to develop water-related illnesses anytime you swim in a body of water. This is especially true for those with a weakened immune system who may experience severe illness if exposed to certain germs when swimming. (Source)
It is always advisable to take your time to let your body adjust slightly to the colder water, or to at least wear a wetsuit designed to keep you warm.
Can Swimming in Cold Water Make a Cold Worse?
Generally, swimming in cold water won’t make your cold worse, but it might feel like it is. If you are trying to decide whether or not you should swim while you have a cold, you can do what is called the “neck test.” If your symptoms are primarily above the neck (sniffles, headache), you may be fine to exercise. However, if your symptoms are below the neck (congestion, coughing), then you should probably rest. (Source)
Keep in mind that the sudden shock from the cold water may exacerbate your sniffling or runny nose, but this doesn’t necessarily mean you’re getting more sick.
Can Swimming in Cold Water Give You a Headache?
Yes, swimming in cold water can give you a headache. This is especially true if you put your head underwater at any point (though this should be avoided at cold temperatures). The feeling can be similar to a brain freeze and can be common for those who surf in cold water (Source).
It is caused by your expanded blood vessels suddenly contracting and potentially spasming. This can cause pain to radiate through your head and across your face.
What Happens if You Swim in A Very Cold Water?
The two primary risks of swimming in cold water are cold shock and hypothermia. Breathing will be impacted in temperatures below 25°C (77°F), so caution should be used beginning at this temperature. Cold water shock can be especially dangerous around 10°C-15°C (50°F-59°F), especially for swimmers who don’t have any experience in cold water. (Source)
Another risk is swim failure. This is when your body is trying to direct blood flow to vital organs, which limits the blood flow throughout the body. At extreme levels, this can cause your arms and legs to stop functioning properly, leading to an inability to swim. If you start to feel yourself getting sluggish or slowing down, you should exit the water immediately. (Source)
The table below shows water temperature ranges and what you can expect to experience:
| Water Temperature | Characteristics |
| 30°C – 40°C (86°F-104°F) | Pleasant temperature, a bit on the warm side |
| 25°-30°C (77°F-86°F) | Cooler feeling, but can feel refreshing as the body warms up |
| 20°C-25°C (68°F-77°F) | Cold water, breathing will be affected |
| 15°C-20°C (59°F-68°F) | Treat anything below 21°C (70°F) with caution |
| 10°C-15°C (50°F-59°F) | Dangerously cold, increased risk of shock |
| Below 5°C (50°F) | Dangerous and painful, should be avoided at all times |
Can You Go Into Shock from Cold Water?
Yes, you can experience what is called “cold shock” from swimming in cold water. This is an incredibly risky situation to be in and happens far quicker than hypothermia. Cold shock is a physiological response where your body initiates a gasp reflex (Source).
If this reflex happens while you’re underwater, you may end up inhaling some water, especially if a wave is coming over your head at the same time. This can cause severe issues with your breathing, even if you only inhale a small amount.
After the initial gasp, you will likely experience uncontrollable hyperventilation, which causes rapid breathing and a feeling of panic. A common response is to go upright while in the water, but this can limit natural buoyancy and ultimately cause drowning.
It is far safer to keep your head above water while your body adjusts to the cold temperature.
For more on this, we highly recommend that you check out our post “What Causes Negative Buoyancy in Humans? (Solutions Listed)“
How Long Is It Safe to Swim in Cold Water?
You shouldn’t plan to swim in cold water for more than 20 minutes. If you are still feeling cold after 10 minutes in the water, you should get out immediately. This is a sign that your body is not acclimating to the cold and will have a difficult time getting back to it’s warm internal temperature. (Source)
Many people who choose to swim in cold water are doing it for a quick, refreshing experience and are generally not spending significant amounts of time in the water.
Regardless of how much time you spend in the water, it’s very important to prepare for your recovery afterward. You will want to take great care in getting warm as quickly as possible to prevent any injury or shock.
How Do You Recover from Cold Water Swimming?
It’s very important to properly warm up after a cold water swim in order to avoid the afterdrop. An afterdrop is when your body temperature continues to drop even after exiting cold water. You can end up feeling cold for 10 to 40 minutes after exiting the water. (Source)
To avoid this, you’ll want to make sure that you warm up gradually after your swim (even though it may be tempting to hop into a scalding hot shower!).
Here are a few things you can do to safely warm yourself up:
- Dry off ASAP and remove all wet layers
- Begin dressing immediately, focusing on your upper body first and layering up with thermals
- Sip a warm drink
- Sit in a warm environment, even if it’s just your car with the heaters on full blast
- If you feel okay, walk around to generate more body heat
Things to keep in mind
Swimming in cold water can be dangerous and poses major risks. However, if you take proper caution and prepare accordingly, it can be an incredibly invigorating experience. If you have any underlying health conditions or concerns, it’s always best to consult a medical professional.
Also, we highly recommend that you check out our post “How Many Ice Baths a Week You Should Take? Does It Work & What To and Not To Do!“
