Cold plunge benefits: what the trials show

Cold plunge benefits, claim by claim

Cold plunge benefits are claimed far more widely than they have been tested. A cold plunge, or ice bath, is a few minutes in water at about 50 to 59°F. Most of what you read about it traces back to a handful of studies, several of them small, on young men, or about cold showers and winter swimming instead of a tub.

We are not medical professionals, and this page is a reading of published research. It makes no promise that a cold plunge will treat anything. Before you start, read cold plunge safety: the risks are better established than the benefits.

What the 2025 review found

The widest look at the evidence is a systematic review in PLOS One from the University of South Australia. It pooled 11 randomised trials with 3,177 healthy adults, in water from 45 to 59°F, for anything from 30 seconds to two hours.

Three results are worth knowing.

Stress fell, but on a delay. It was lower 12 hours after a plunge and unchanged at every other point measured, including straight after. If you get out of the tub feeling calm, the pooled trials did not find that effect.

Sleep and quality of life improved. Mood did not.

Inflammation went up, not down. It rose immediately and was still raised an hour later, which the authors call an acute inflammatory response. That is the opposite of how cold plunging is usually sold.

The authors’ own caution closes the abstract: the evidence is “constrained by few RCTs, small sample sizes, and a lack of diversity in study populations”.

Does a cold plunge help muscle recovery?

A little, for soreness. A review of nine trials concluded that cold water “can be slightly better than passive recovery in the management of muscle soreness”. The best results came from water at 52 to 59°F for 11 to 15 minutes, in supervised trials on athletes. That is longer than the five minutes Cleveland Clinic advises at home, which is why how long to cold plunge sides with the clinic.

Mayo Clinic Health System describes the mechanism as less exercise-induced muscle damage, which means less soreness and better performance the next day.

The one proven downside: muscle growth

If you lift to get bigger or stronger, this is the finding to take seriously. In a 12-week trial, 21 active men strength trained twice a week. One group took 10 minutes of cold water after each session and the other did an active cool-down.

The authors wrote that using cold water “as a regular post-exercise recovery strategy should be reconsidered”. Mayo Clinic Health System says the same effect does not appear to apply to endurance training. Timing your plunge around this is covered in when to cold plunge.

Dopamine, norepinephrine and the one-hour study

The figure you see quoted most, a 250% rise in dopamine, is real and comes with a condition that is usually left out. In the study behind it, young men sat up to the neck in 57°F water for a full hour. Noradrenaline, also called norepinephrine, rose 530% and dopamine rose 250%. Metabolic rate rose 350%, and heart rate and blood pressure rose with it.

An hour is twelve times the longest session Cleveland Clinic advises. The study did not measure a two-minute plunge, and it did not measure mood. It shows that cold water switches on the sympathetic nervous system, the body’s alarm system. It does not show how you will feel afterwards.

Do cold plunges boost immunity?

The evidence is one large trial of cold showers, not plunges. In the Dutch trial, 3,018 adults finished their showers with 30, 60 or 90 seconds of cold water for 30 days, or showered as usual. The cold-shower groups took 29% fewer sick days off work. They reported just as many days of being ill.

So the showers changed whether people went to work, and did not change whether they got sick. The 2025 review found no effect on immune function immediately after cold water or an hour later.

Brown fat and metabolism

Brown fat is tissue that burns energy to make heat. A Danish study compared young men who winter swam two to three times a week, with sauna sessions, against men who did not. In response to cold, the swimmers produced more heat. The authors propose winter swimming “as a potential strategy for increasing energy expenditure”.

It was a comparison of two groups, not a trial, so it cannot say the swimming caused the difference. It studied men who paired cold with sauna. Nothing in it supports a cold plunge as a way to lose weight.

What the evidence does not show

• A treatment for depression or anxiety. The 2025 review found no effect on mood.
• Lower inflammation. The pooled trials found a short-term rise.
• A stronger immune system. One trial, of showers, with sick days and illness pointing different ways.
• Weight loss. No trial we read measured it.
• Any benefit for people with health conditions. The trials enrolled healthy adults. A preventive cardiologist quoted by American Heart Association News said of cold water: “Whether there are health benefits or not is not clear and has not been established.”

We also read no trial on the vagus nerve, which is often named as the reason a plunge feels calming. We leave it out for that reason.

So is it worth doing?

Go in for the reasons the trials support. Less soreness after hard training, and possibly better sleep. Those are modest, and they are what the evidence has.

Do not buy a tub for a claim on the list above. And if muscle growth is your goal, keep the cold away from your lifting sessions.

If the evidence is enough for you, the cheapest way to try it is a bathtub and a bag of ice. How to cold plunge at home covers a first session, and the best cold plunge tubs covers what to buy if the habit sticks.

Common questions