Cold water swimming and cold exposure are still growing in popularity, so this winter we are sure to spot frost-proof enthusiasts cutting a hole in the ice and happily splashing about in it. It is no surprise, as cold exposure has many health benefits and noticeably lifts your mood. Even so, it is a tricky business, and you need to know how to do it properly so you do not end up with a nasty cold, pneumonia or, in the worst case, even lose your life. What are the most common mistakes beginners make, and what should you watch out for?
Short answer. The most common cold exposure mistakes are starting too abruptly in the middle of winter, going alone, drinking alcohol to warm up and taking a hot shower straight after getting out of the water. Instead, start in autumn with cold showers and short dips, enter the water slowly and get out as soon as you cannot calm your breathing or your fingers start to go stiff. If you have a heart condition or another chronic illness, talk to your doctor first.
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Health benefits of cold exposure
Young or healthy, men or women, cold exposure can have positive effects on the health of all of us. With regular (moderate) exposure to cold, our body gains the ability to respond well to large swings in temperature and adapt to them better. In practice, this means that light morning frosts will no longer throw you off as much.
Regular cold exposure may also support your immunity. However, research has not yet provided convincing evidence that you will catch flu, tonsillitis or the common cold less often.
Cold also makes the blood vessels in the skin constrict, and once you warm up, they widen again. According to the British Heart Foundation, regular cold water swimming may improve blood pressure and blood fat levels in people in good health, but people with heart disease must discuss cold exposure with their doctor first. Research also suggests a possible effect on fat tissue and insulin sensitivity. For mental resilience, faster muscle recovery, stress resistance or easing depression, however, the evidence is still weak.
Cold exposure can also be beneficial for pregnant women, but ideally they should have some experience before conceiving. In this case it is especially important to listen to your body and not force anything. You can start carefully in the shower, letting cold water run over you for the last few minutes, then gradually extend this time and make the water colder. Before you start, and especially before your first dip in cold water outdoors, discuss cold exposure with your doctor.
Cold exposure and immunity, what studies say
The most thorough study of the question was a Dutch randomised trial by Geert Buijze’s team at the Academic Medical Center in Amsterdam, published in the journal PLOS ONE in 2016. It involved 3,018 adults aged 18 to 65 without serious illnesses. For thirty consecutive days, they finished their warm shower with 30, 60 or 90 seconds of cold water at roughly 10 to 12 °C, and for the next 60 days they took cold showers at their own discretion. The control group showered as usual.
Over the full 90 days, people in the cold shower groups had 29% less sickness absence from work. However, the number of days they were ill did not differ from the control group, and it made no difference whether they showered for 30 or 90 seconds. So cold showers did not stop them getting ill; according to their own reports, illness simply held them back less. All data were self-reported, and participants knew which group they were in.
The most frequently mentioned benefit was a feeling of having more energy, and 64% of participants carried on with cold showers after the trial ended. This is especially useful in autumn, when many people are looking for ways to beat autumn fatigue.
A broader view comes from a review by physiologist Mike Tipton and colleagues at the University of Portsmouth, published in 2017 in the journal Experimental Physiology. According to the review, there are signs that short bursts of cold stress may prepare the immune system for strain. However, the optimal dose of cold is not known, and too much cold may actually suppress immunity.
A Norwegian review by Esperland, de Weerd and Mercer from 2022 looked at 104 studies and points out that most of them worked with small groups of people, so the question remains open. Treat cold exposure as one piece of the puzzle. You will find others in the article 11 tips and tricks for boosting your immunity.
Cold exposure when you have a cold or are ill
The Czech Industrial Health Insurance Company (Česká průmyslová zdravotní pojišťovna) recommends pausing cold exposure during acute illnesses, including a runny nose or cough, and returning to it only once the symptoms have gone. Cold is extra stress for the body, and during illness it is better to let it rest rather than add more strain.
After an illness, do not pick up where you left off with the temperatures you had reached before. According to the same source, the body has to get used to the cold again. So start again with a cold shower or a shorter time in the water, and increase the load gradually, as if you were a beginner.
Risks and mistakes in cold exposure
As already mentioned, however, cold exposure requires training, and we cannot expect all our health problems to disappear if we suddenly jump into a frozen lake in the middle of winter without any preparation. Not only would this give our body a temperature shock, it could also become life-threatening, as the icy water could paralyse us and we would be at real risk of drowning.
For older people, those with a weaker heart or anyone who does not lead an active lifestyle, the temperature shock can be so great that it may cause cardiac arrest. Cold exposure is therefore definitely not just amateur fun; it needs to be approached responsibly, with your safety always coming first.
Cold shock, why the first minutes are the most dangerous
In the review mentioned above, Tipton and colleagues describe that the biggest threat to someone unaccustomed to cold is not hypothermia but the first three minutes in the water. Rapid cooling of the skin triggers what is known as cold shock, an involuntary deep gasp followed by uncontrollably fast breathing. Inhaling just a little water is then enough. According to the authors, this very reaction is behind most deaths in cold water.
According to Tipton and colleagues, water below 15 °C is considered cold. Laboratory measurements show that cold shock is strongest in water at 10 to 15 °C and does not increase further in even colder water. The review also cites a 1977 report by the British Home Office, according to which roughly 55% of people who drowned in open water died within three metres of safety, and two thirds of them were considered good swimmers.
So do not jump into cold water and do not put your head under straight away. Enter slowly, pause for a moment and focus on a calm, long exhale until your breathing settles. You can train your breath control in advance, for example with the article how to breathe properly with breathing exercises. Tipton also warns that putting your face under water or getting a wave in the face, combined with cold shock, can disrupt the heart rhythm even in young and healthy people.
The body does get used to the cold, though. A meta-analysis by Barwood, Tipton and other authors, published in 2024 in the Journal of Thermal Biology, confirmed that the heart rate during cold shock drops by an average of 14 beats per minute after repeated immersions. According to earlier work, this habituation sets in after roughly four immersions. An older trial by Tipton’s team showed that six three-minute immersions in water at 15 °C blunted the response even in water at 10 °C.
Fear, however, slows habituation down. In a 2017 trial by Barwood and colleagues, habituation did not occur in people who were repeatedly stressed during immersions. This is another reason why it pays to start calmly, without egging each other on, and in company you feel safe with.
Who should avoid cold exposure
According to the Czech Industrial Health Insurance Company (Česká průmyslová zdravotní pojišťovna), time in cold water is risky and not recommended for people with more serious diseases of the heart, urinary tract or kidneys, or with a neurological condition such as epilepsy. The British Heart Foundation adds that people with heart disease should discuss cold exposure with their doctor first, because cold shock speeds up the heart rate, raises blood pressure and increases the risk of heart rhythm problems.
Tipton points out that fatal rhythm disorders in cold water occur mainly in people with a predisposition, for example long QT syndrome, coronary heart disease or an enlarged heart muscle. Many of these conditions develop over a person’s lifetime, and some medicines can also prolong the QT interval. If you take any medication regularly, ask your doctor whether cold exposure is suitable for you.
Also watch out for cold urticaria. The New Zealand dermatology website DermNet states that swimming in cold water is the most common cause of a severe reaction, which can lead to a drop in blood pressure, shock and collapse. We recommend that pregnant women consult a doctor, as mentioned above, and anyone who currently has an acute infection should wait before trying cold exposure.
Common cold exposure mistakes and how to fix them
Cold exposure can bring great benefits to our health, but we need to avoid several key mistakes that even experienced, hardened veterans make every year. These mistakes can not only sabotage our progress but also put our health or even our life at risk.
1. Everything takes time
Although jumping into a frozen pond to celebrate the new year can be very tempting, it carries serious health risks, from temperature shock and colds to cardiac arrest. Besides plunging into icy water, there are other ways to practise cold exposure, for example with ice and air. So start your cold-water career gently, perhaps by removing one layer of clothing, rubbing a few ice cubes on the back of your neck or showering with cold water.
2. Don’t drink alcohol to warm up
Folk wisdom says that if you are cold, a shot of homemade brandy will warm you up and protect you from the flu. It may feel as though you really are warmer for a moment, but alcohol will soon make things worse.
In reality, that “warming up” sends blood rushing around the whole body, which disrupts the body’s natural tendency to keep it around the vital organs. As the blood flows, your body temperature rises briefly, but in a cold environment you lose that heat very quickly. Alcohol also has a negative effect on shivering, which is your body’s way of trying to warm you up. A good alternative for warming up after a cold session is a warm tea or a hearty soup.
3. Wait before taking a hot shower or bath
As soon as you start exposing your body to the cold, you quickly realise that you need to warm it up again fast. Whether you take ice baths or cold showers, or remove layer after layer in cold weather, a warm shower is very tempting as a way to get your body back to a comfortable temperature.
However, a hot shower straight after getting out can cause a drop in blood pressure and fainting, so only shower once you have warmed up. You are also likely to irritate your skin. You can go somewhere warm straight away, just avoid hot showers and baths until you have warmed up. Get dressed as soon as possible and warm your body up by moving. You don’t need to sweat or run marathons around the pond. A gentle walk or light movement after getting dressed is enough.
4. Don’t start in the middle of winter
Most people throw themselves into cold-water swimming only when social media starts filling up with half-naked people in snowdrifts and frolicking in icy rivers. Bear in mind, though, that these are experienced cold-water swimmers, for whom this is probably not their first season, or who prepared carefully for the move to outdoor conditions.
The ideal time to start is the end of summer or the beginning of autumn. The changing season gives you a gradual temperature transition from warm ponds to colder water. If you go swimming in outdoor waters at least twice a week from the summer onwards, you will be well prepared for the winter frosts.
5. Don’t go alone
The idyllic quiet of nature may tempt you to enjoy a peaceful moment alone, but don’t take the risk. Always go with someone who knows where you are and can help you in an emergency. There is nothing to be ashamed of. Even people with many years of experience go cold-water swimming in larger groups. Find out whether there are regular cold-water meet-ups in your area and gather inspiration from the people around you.
6. Combine cold exposure with regular exercise
Think about why you want to start cold-water training in the first place. Whether you want to lower your blood pressure, strengthen your immunity or are looking for help with burning fat, don’t forget to add the most important thing to this healthy habit: regular exercise. Even the most sophisticated cold-exposure routine cannot make up for a sedentary lifestyle and a poor diet. If you are serious about your health, definitely don’t skip exercise.
7. Talk to your doctor about cold exposure
This point applies especially if you know you have a health problem, don’t exercise regularly or react worse to the cold than the people around you. A healthy body can benefit from cold exposure, but everyone’s body is different and we all face different problems, so there is no such thing as universal advice like “Cold exposure is suitable for everyone”.
Every year, paramedics are called out to hypothermic swimmers who were far too motivated and overestimated their abilities, and sadly in some cases they arrive too late. Exposing yourself to the cold is above all about the health benefits, so put your health and well-being first and, to be on the safe side, ask your doctor for a professional opinion.
8. Don’t get sweaty or out of breath before going in
Before entering a cold environment, whether it is a shower, the air or an ice bath, your body should be at a comfortable temperature with a resting heart rate. A light warm-up or a gentle walk is fine, but you definitely shouldn’t be out of breath and sweaty.
9. Forget about driving
If you have already plunged into icy water, you will certainly have noticed that your body and mind are slowed down when you get out. This is because the cold affects our cognitive functions and the body is in emergency mode, where its only task is to stay alive and warm up. This also affects our ability to react quickly. You can go somewhere warm straight away, for example into a heated car, just avoid hot showers and baths until you have warmed up. But think of your own safety and that of other road users, and it is better not to get behind the wheel after cold-water swimming.
10. Don’t push yourself to prove a point
Enthusiasm and determination to achieve the best results are commendable and will certainly bring you plenty of success, but with cold exposure it pays to listen to your own body and expose yourself to the cold sensibly. If you feel more uncomfortable in icy water than usual, notice your muscles stiffening or can’t take a deep breath, don’t force it and get out of the water.
A popular rule of thumb says you should stay in cold water for as many minutes as the water has degrees, so ten minutes at 10 °C and five minutes at 5 °C. However, this is not an established rule. Instead, pay attention to how you feel in the water to prevent hypothermia or other serious complications.
How to start cold-water swimming in autumn
Autumn is ideal for beginners, because the water cools gradually and the body has time to adjust. The Czech Industrial Health Insurance Company (Česká průmyslová zdravotní pojišťovna) advises planning cold exposure for children in spring or autumn, when the weather is more favourable, and the same logic applies to adults. You can start at home in the shower and move to open water once you have got used to the cold a little.
- Cold shower. At the end of your usual warm shower, turn on cold water for 30 seconds and gradually increase the time. Participants in a Dutch cold-shower experiment started in the same way.
- Regularity. It is better to do short sessions several times a week than a long one every now and then. According to research so far, cold shock weakens after roughly four immersions.
- Outdoor water. While a pond or river is still relatively warm, go for short swims and you will adjust gradually as the water cools.
- A tub or barrel at home. If you don’t live near water, you can practise in your garden. The same rules apply as outdoors: a slow entry, a short stay and never alone.
- Breathing. Don’t do deep, rapid breathing before going in. Breathing exercises belong on dry land.
Many people associate cold exposure with the Wim Hof breathing method. However, the method’s official website warns that intensive breathing can in rare cases lead to loss of consciousness, so it should never be practised in water, in the shower or while driving. Do breathing exercises sitting or lying down at home, not just before a plunge or in the water.
Treat your first season as preparation. The goal is not to stay in as long as possible, but to learn to enter cold water calmly, get through the first few minutes and get out in time. Only increase the length of your stay once getting into the water no longer gives you trouble.
How long to stay in cold water
There is no universal table, and the rule of thumb of one minute per degree from point ten is only a rough guide. According to Tipton’s review, the rate of cooling varies with water temperature and currents, body size and composition, and how used to the cold a person is. Two people in the same water may therefore have completely different limits.
After the first minutes of cold shock comes the second phase: cooling of the muscles and nerves in the arms and legs. According to Tipton, a local temperature of 5 to 15 °C can block the nerves after 1 to 15 minutes to such an extent that the effect resembles paralysis. A person then cannot swim or hold on at the bank. The arms are the most vulnerable, because they have a large surface area relative to their mass.
Hypothermia itself comes later; according to the same review, in an adult it does not set in earlier than after 30 minutes, even in icy water. So don’t judge by whether you have started shivering yet. The signals to get out are stiff fingers, clumsy movements and difficulty breathing or speaking. In your first season, get out earlier rather than later. Confidence comes with the number of plunges, not the length of one.
Hypothermia and afterdrop, how to warm up after cold-water swimming
According to the British health service, the NHS, hypothermia is a drop in body temperature below 35 °C, while normal temperature is around 37 °C. Symptoms include shivering, pale and cold skin, blue or grey lips, slurred speech, slow breathing, tiredness and confusion. Anyone with these symptoms needs help. Call your local emergency number: 112 in Europe, 911 in the USA and Canada, 999 in the UK (in the Czech Republic: emergency medical service 155).
After you get out of the water, your body can keep cooling for some time, a phenomenon known as afterdrop. A French study by Drigny and colleagues from the University of Caen, published in 2023 in the International Journal of Sports Physiology and Performance, followed 14 swimmers in water at 12.5 to 13 °C. After swimming for an average of more than three hours, their core body temperature kept falling for roughly 25 minutes after they got out, on average from 35.2 °C to 34.7 °C. People with a higher BMI and body fat percentage kept cooling for longer.
A recreational dip is much shorter, but you should still expect to feel cold for a while after getting out. So dry yourself straight away, put on dry layers including a hat, and warm up with a gentle walk or light movement, as we advise in point three. Heather Massey from the University of Portsmouth recommends exactly this kind of light activity, such as a gentle walk, and warns that a hot shower or getting out of a hot bath can lead to collapse because your blood pressure cannot adjust quickly enough. Warm tea from a flask also helps.
According to the NHS, a person with signs of hypothermia should be moved somewhere warm or sheltered from the wind, have their wet clothes removed, be wrapped in a blanket or dry towel and be given a warm non-alcoholic drink and something sweet. On the other hand, do not use a hot bath, a hot water bottle or a heat lamp, do not rub their arms and legs, and do not give them alcohol. They need to be warmed up gradually, just as after an ordinary cold-water dip.
What to take to the water
A cold-water swimmer’s kit is simple and does not have to be expensive. It pays most to protect your hands and feet, which get cold quickly and are easily injured on stones or ice. The following items will see you through the whole season.
- Neoprene boots or socks, which protect against sharp stones and slow down how quickly your feet get cold.
- Neoprene gloves, which keep your fingers working for longer.
- A towel and a changing poncho or robe, so you can change quickly.
- Dry, warm clothes for layering, plus a hat and gloves for the journey home.
- A flask of warm tea, as we advise in point two.
- A water thermometer, so you know what you are getting into.
- A charged phone and, above all, a companion who stays on the shore.
Lay out your clothes in the order you will put them on and keep them in a bag so they do not get damp. Cold fingers struggle with zips and buttons, so loose clothing without fiddly fastenings is ideal. Do not forget a mat to stand on either, as changing on frozen ground is difficult.
