“Anti-inflammatory” is printed on half the cold plunge ads you will see. It sounds like a medical benefit, and it is rarely explained.
This article looks at what trials measured. It sits under our overview of cold plunge benefits. It is general information, not medical advice.
Short answer: cold narrows blood vessels and can reduce local swelling for a while, Cleveland Clinic says. But the largest review of trials found that blood markers of inflammation went up, not down, immediately and 1 hour after cold water. And where cold does damp inflammation after training, it may also damp muscle growth.
The two claims hiding in one word
“Reduces inflammation” can mean two different things:
- Local swelling. Cleveland Clinic: “the cold constricts blood vessels, temporarily reducing swelling and inflammation to aid recovery.” This is the effect people feel in sore legs.
- Body-wide inflammation, measured in the blood. This is what the marketing implies when it lists inflammation next to immunity and longevity.
The research says different things about each.
What the trials measured
A 2025 systematic review in PLOS One pooled 11 randomized trials of cold water at 7 to 15°C, in 3,177 people.
The result: “significant increases in inflammation immediately” after cold water, and again 1 hour after. The review doesn’t report a fall at any time point.
| Time after cold water | Inflammation (2025 PLOS One review) |
|---|---|
| Immediately | Higher |
| 1 hour | Higher |
The authors call the effects “time-dependent,” and they note the limits: “few RCTs, small sample sizes, and a lack of diversity in study populations.”
The training trade-off
Where cold does damp the body’s response to exercise, it has a cost. Cleveland Clinic: “The way cold therapy reduces inflammation can also silence the muscle-building signals.”
A 2015 study in the Journal of Physiology showed the same thing in muscle tissue. Men who sat in cold water for 10 minutes after strength training gained less muscle and strength over 12 weeks, and biopsies showed weaker growth signals in the 48 hours after each session.
Here’s what the ad won’t tell you. Some of the inflammation after a workout is part of how training works.
What about inflammatory diseases?
A 2017 review in Experimental Physiology looked at cold water for “the prevention of inflammation and treatment of inflammation-related conditions.” It concluded that while there is often “a credible rationale,” in some areas “the supporting data remain at the level of anecdotal speculation.”
A 2014 study in PNAS found lower inflammatory markers after an injected toxin in people trained in breathing, meditation, and cold exposure. The training combined all three, so it doesn’t isolate the cold water.
If you have an inflammatory condition, that is a conversation for your doctor, not a tub.
Who should check with a doctor first
Cleveland Clinic lists heart disease, high blood pressure, diabetes, pregnancy, peripheral neuropathy, poor circulation, venous stasis, and cold agglutinin disease. Its home limits: start at 50 to 59°F, a minute or two, never longer than five minutes, never below 40°F.
My rule of thumb: if swollen, sore legs are the problem, cold helps a little. If “inflammation” on a sales page is the reason, read it as a feeling, not a measured result.
What to buy, if anything
For sore legs after the odd long session, ice in a soft tub does the job. The Nurecover Pod is $129. A chiller tub like the Renu Cold Stoic 2.0 at $9,499 is a lot of money for an effect the trials haven’t shown.
Bottom line: cold eases local swelling for a while. It hasn’t been shown to lower inflammation in the blood, and the best review found a short rise. For the other claims, see the cold plunge benefits overview linked above.
Sources
- Cain T, et al., “Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis,” PLOS One, January 29, 2025: journals.plos.org
- Cleveland Clinic, “Are ‘Cold Plunge’ Ice Baths Good for You?” May 8, 2026: health.clevelandclinic.org
- Roberts LA, et al., “Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training,” Journal of Physiology, 2015 (abstract): pubmed.ncbi.nlm.nih.gov
- Tipton MJ, et al., “Cold water immersion: kill or cure?” Experimental Physiology, 2017 (abstract): pubmed.ncbi.nlm.nih.gov
- Kox M, et al., “Voluntary activation of the sympathetic nervous system and attenuation of the innate immune response in humans,” PNAS, 2014 (abstract): pubmed.ncbi.nlm.nih.gov
- Nurecover Pod and Renu Cold Stoic 2.0 listings, checked September and October 2026