Is Cold Water Dangerous? The Truth About Deliberate Cold Exposure

Cold water therapy has seen a growth in popularity — from cold plunges and ice baths to invigorating winter swims. With more people turning to these practices for mental clarity, physical resilience, and nervous system regulation, it’s no surprise that the headlines have followed. But recently, some of those headlines have sounded alarm bells: "Cold water could be harmful," "Ice baths linked to kidney issues," or "Cold plunging isn't for everyone."

So, what’s the truth?

The short answer: Yes, cold water can be dangerous. But context is everything. Not all cold water exposure is the same, and understanding the distinctions is vital for staying safe — and getting the most out of the practice.

Defining deliberate cold exposure

Let’s be clear: we’re talking about deliberate cold exposure — not falling into an icy lake, not staying in freezing water for extended periods, and not attempting extreme challenges without preparation.

Deliberate cold exposure typically involves intentional, short-duration immersion in water between 6°C and 15°C. This could be a cold shower, plunge pool, or natural body of water. The goal is to activate positive stress responses in the body — not shock it into danger. Exposures often last between 30 seconds and 3 minutes, practiced consistently for physical and mental benefits. Temperatures below 5°C are generally considered ice swimming (Søberg, 2024).

Like any training — Build gradually

Would you go out and run 20km without having trained for it? Probably not. Cold exposure works in the same way — it’s a stressor, and your body needs time to adapt.

Start small. Begin with higher water temperatures and shorter durations. As your body adjusts — a process called habituation — you’ll be able to tolerate colder temperatures more comfortably. Ideally, begin in the milder months to prepare your body for the chillier dips of winter.

This isn’t about heroics. It’s about consistency and listening to your body.

Know the risks - and how to stay safe

There are real risks when it comes to cold water, including cold shock response and hypothermia. Cold shock can cause rapid breathing, increased heart rate, and panic — especially if you jump in too quickly. Hypothermia, while less likely in short exposures, is a danger if you're in cold water too long or not dressed appropriately.

Safety first:

• Enter the water slowly.

• Splash your body with water before full immersion to prepare your skin receptors.

• Stay within your limits — especially if you're new.

• Avoid exposure if you're ill or experiencing high stress.

• Always warm up safely after.

If you have any underlying health conditions, consult with your GP before starting cold therapy.

How much is too much?

More is not always better. Dr. Susanna Søberg suggests that the optimal dose of cold exposure is around 11 - 12 minutes per week, spread over several sessions. That might mean 3 - 4 minutes across 3 - 4 days - not daily plunges lasting 10 minutes.

As you become more habituated, you can tolerate colder temperatures — but the colder the water, the less time you need to be in it. It’s not a competition. It's about the impact it has on your body and mind.

The benefits of deliberate cold exposure

So why do people keep coming back to the cold?

When practiced safely and consistently, cold water exposure offers a range of science-backed benefits, including:

• Improved mood and mental clarity - Cold exposure triggers a release of dopamine and norepinephrine, which can elevate mood and increase alertness.

• Reduced inflammation - Cold can help reduce systemic inflammation, which supports recovery from training or chronic stress.

• Resilience training for the nervous system - Short bouts of cold act as a hormetic stressor, helping the body and mind adapt to future stress more effectively.

• Improved circulation and cardiovascular tone - Cold causes blood vessels to constrict and then expand, supporting vascular health.

• Enhanced willpower and discipline - Consistently facing the cold builds mental toughness and confidence.

These effects are not just anecdotal — emerging research, including work from scientists like Dr. Susanna Søberg and Dr. Andrew Huberman, supports many of these outcomes when cold is used deliberately and in moderation.

Should you cold plunge if you’re ill or menstruating?

Cold exposure triggers a stress response. That’s the point - a small, controlled dose of stress that strengthens your system. But if you’re already ill, your body is already under stress. The same goes for menstruation, particularly during the early phase of your cycle when your body may be more sensitive.

There isn’t yet robust research in these specific areas, but common sense applies. If you’re unwell or not feeling 100%, give your body space to rest. The cold will be there when you’re ready.

What about all the scary headlines?

Recently, I was sent a post claiming a link between cold plunges and kidney stones. Can cold stress play a role in exacerbating underlying conditions? Possibly. But these headlines rarely explore the full picture: What was the water temperature? How long were they in? How frequently were they doing it?

Like any wellness trend, cold exposure is at risk of being sensationalised. As with supplements, diets, and fitness protocols, individual response matters. One person’s life-changing ritual might be another’s stress overload. That’s why education is key.

We need to look beyond clickbait and understand the what, why, how, and who it’s for.

Final thought

Everybody is different, and I know the cold isn’t for everyone. But in my experience, like with everything,  it’s hard to truly understand its impact until you’ve tried it.

As the founder of Reyt Sauna - a cold plunge and sauna experience set in nature - the thing I hear most is, “I don’t like the cold.” My response is always the same: “I don’t like being cold either - but I love how it makes me feel.”

The benefits have been profound. Cold water makes me feel alive, motivated, and clear-headed. It cuts through the mental fog and brings me into a state of total presence, where everything else fades away.

I didn’t set out to find this feeling. It started with open water swimming during triathlon training. But as temperatures dropped, I noticed I liked it, a mix of buzz and clarity that stayed with me.

I’ve also found that cold water and contrast therapy feel very different. Cold on its own brings alertness and drive. The hot-cold combination is more grounding - almost meditative.

Resilience is another big one. As a solo parent of three, mornings can be full-on. But a quick dip changes how I respond. Those little challenges don’t get to me the same way.

Looking back to two years ago, I was going through a tough time. My nervous system was constantly on edge.  I now understand I was dysregulated, and cold exposure helped reset things. That’s what sparked my deeper interest in the science behind it all - how it supports us physiologically, psychologically, and neurologically.

If you’re curious about cold exposure, we’d love to welcome you to Reyt Sauna. Whether you're just starting out or returning to yourself in new ways, you won’t be doing it alone, we’re here to support you, every step of the way.