Cold Water Immersion , immune system and inflammation
Cold Water Immersion & Immunity: How Cold Sharpens Your Defence System. Most of us have felt that jolt when we step into cold water—heart pounding, breath catching. But what if that intense moment is doing more than waking you up? What if it’s also boosting your immune system? Cold Water Immersion (CWI)—whether through cold showers, dips in the sea, or ice baths—triggers a series of powerful responses in the body that can strengthen your immunity, reduce inflammation, and help you recover faster from illness or stress. Let’s break it down.
Posted on Fri 16 May 2025 · by Danny
Activating the lymphatic system
Cold exposure causes blood vessels to constrict, which helps move lymph through the body. The lymphatic system doesn’t have a pump like the heart, so it relies on movement and pressure. The cold acts as a trigger—helping flush waste and pathogens and supporting the movement of white blood cells to where they’re needed most.
Norepinephrine and inflammation
One of the first things that happens during CWI is a spike in norepinephrine. This stress hormone helps sharpen focus but also plays a key role in suppressing inflammatory cytokines. Cytokines are chemical messengers that drive inflammation—too many, and the body starts to struggle. By reducing them, cold water helps keep the immune system in balance and inflammation in check.
More white blood cells, more immune power
Studies have shown that daily cold showers can lead to an increase in white blood cells. These include natural killer (NK) cells, which hunt down viruses and tumour cells, and lymphocytes, which include T cells and B cells—the backbone of long-term immunity.
In one study, mice exposed to cold water lived longer after being injected with tumours. Researchers linked this effect to an increase in active T lymphocytes. In humans, cold exposure has been shown to increase levels of IL-6, IL-7, IL-4, and CD8+ cells—all part of the immune toolkit.
The oxidative stress paradox
Initially, cold water increases oxidative stress in the body. This is normal—it’s a short, acute stressor. But with regular exposure, the body adapts by producing more of its own antioxidants, like glutathione. These protect cells from damage caused by free radicals and help slow cellular ageing. Over time, oxidative stress actually drops, and resilience builds.
What’s the takeaway?
Cold water immersion, done regularly and with care, helps the body:
Reduce chronic inflammation
Increase immune activity
Build resilience to illness and stress
Improve recovery
This isn’t about extremes. It’s about regular, consistent exposure. A cold dip after a sauna, a river swim, or just 30 seconds at the end of your shower—it all adds up. Start where you’re at. Listen to your body. And let the cold do its work.