Cold-water immersion (CWI), particularly ice baths, has become a popular practice among athletes and wellness enthusiasts. Proponents claim that frigid showers, baths, and swims can speed recovery, numb pain, prevent colds, and lift mood. However, the science behind these claims is still developing, and it's essential to understand both the potential benefits and risks before taking the plunge.
What is an Ice Bath?
An ice bath is a type of cold-water immersion therapy where a person immerses their body in a bath filled with ice and very cold water. Ice bath temperatures typically range from 50°F to 59°F (10°C to 15°C) and may sometimes be colder. Other examples of CWI are cold-water swimming, cold showering, and cold plunges, which involve short immersion in a pool or a natural body of very cold water.
Potential Benefits of Ice Baths
Some studies suggest that ice baths may offer various health benefits, including:
Improved Muscle Recovery
A 2022 review includes several studies that suggest CWI therapy after physical activity may have the following effects on muscles: reducing muscle soreness, improving muscle recovery, and helping to prevent injuries. Researchers believe that CWI may cause these potential benefits by decreasing blood flow and lowering metabolic activity in the muscles.
Reduced Inflammation
Inflammation is part of the body’s response to illness or injury. Muscle damage that occurs during exercise is a form of inflammation. In the short term, inflammation can be helpful for healing. However, high levels or prolonged periods of inflammation can be harmful. A 2025 review suggests that CWI may reduce inflammation after physical activity. However, the review also presents conflicting evidence that suggests CWI might increase inflammation immediately after and 1 hour after exposure. More large-scale, reliable clinical studies and long-term data are necessary to determine how ice baths affect inflammation.
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Improved Immune Function
A 2020 review notes that cold-water swimming may boost immune activity, increasing levels of certain white blood cells. Some previous studies have also found that people who practice cold-water swimming have fewer respiratory tract infections, with one study showing 40% lower incidence rates. However, another review focusing on cold-water baths and showers had more complex results. The studies the researchers analyzed did not show a change in immunity immediately after or 1 hour after CWI. But long-term results suggested that people who took cold showers reported less absence from work due to sickness. More research is necessary to determine whether CWI has benefits for immunity.
Improved Mental Health and Cognitive Ability
Some studies suggest that CWI therapy may improve mood and cognitive ability and reduce symptoms of mental health conditions. However, others report no improvements. For example, people who took part in a 2023 study on CWI therapy reported feeling more inspired, active, alert, attentive, and proud. They also reported reductions in symptoms of mental health conditions, including distress, nervousness, low energy levels, and low motivation. The researchers suggest that the potential cognitive benefits of CWI may relate to connectivity changes in brain networks. But while some studies included in a 2025 review also suggest that CWI therapy may significantly improve mood, others found no mood improvements.
Potential Metabolic Benefits
CWI seems to reduce and/or transform body adipose tissue, as well as reduce insulin resistance and improve insulin sensitivity. This may have a protective effect against cardiovascular, obesity, and other metabolic diseases and could have prophylactic health effects. Habitual cold-water immersion may help to reduce or change fat tissue, according to laboratory research done on rodents. These changes theoretically could lead to other downstream health benefits, including reduced cholesterol and improved blood sugar.
Risks of Ice Baths
Ice baths and other types of CWI have several risks, some of which are serious. According to the National Center for Cold Water Safety, sudden immersion in water colder than 60°F (15.5°C) can kill a person in less than 1 minute. Research on CWI often uses water that is at this temperature or colder.
The risks include:
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Cold Shock
When a person’s skin makes contact with cold water, they can experience cold shock, which causes an involuntary and rapid increase in heart rate, blood pressure, and breathing. The shock can impair a person’s ability to think and to swim and can cause gasping and panic. If a person gasps while under water, they may risk drowning. Sudden submersion in chilly water can trigger a cold shock response that causes you to gasp and hyperventilate. If your head is underwater, this involuntary gasp and disruption to normal ventilation patterns could lead to drowning. The cold shock response also increases breathing, heart rate, and blood pressure, all of which could pose health risks for people who are susceptible to cardiac events.
Heart Problems
Cold exposure causes the blood vessels to constrict and can force the heart to work harder. In people with existing heart conditions, this could be dangerous. Plunging the body into cold water triggers a sudden, rapid increase in breathing, heart rate and blood pressure known as the cold shock response. That can cause a person to drown within seconds if they involuntarily gasp while their head is submerged. Blood rushes away from the extremities to the body's core to protect vital organs, Plutzky said. That leaves the arms and legs without good circulation, which can lead to a loss of strength and coordination. The rapid loss of heat also can lead to hypothermia, making it harder to think clearly or move well.
Hypothermia
CWI reduces the body’s temperature rapidly. This may lead to hypothermia, which can affect a person’s ability to move or think properly and can eventually affect organ functioning.
Nerve and Skin Damage
Repeated or long exposure to very cold water may result in ice burn or frostbite, which can damage skin tissue and nerves.
Breathing Difficulties
Cold water can trigger rapid, uncontrolled breathing (hyperventilation). This can be dangerous if it leads to dizziness or fainting, especially while in the water.
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Cardiovascular Stress
Cold water causes your blood vessels to constrict, which raises your blood pressure and forces your heart to work harder. According to the American Heart Association, cold plunging can cause a sudden increase in breathing, heart rate and blood pressure. This can be dangerous for people with heart conditions, hypertension or those at risk for stroke.
Who Should Avoid Ice Baths?
The risks of CWI may be especially high for people who have underlying health conditions, such as heart disease or hypertension, or take medications such as beta-blockers. People who have never tried CWI before should not try ice baths without talking with a doctor first, especially if they have any chronic conditions or take any medications. People with health conditions that affect the cardiovascular system may need to avoid CWI entirely. This includes people with:
- Diabetes
- Heart disease
- Hypertension
- Circulatory issues
How to Take an Ice Bath Safely
Even for people who can try ice baths, it is essential to follow safety advice to reduce the risks. If a person wants to try ice baths, it is important that they prepare properly. This means:
- Choosing a time and place for the bath when others will be around
- Starting with warmer temperatures and gradually decreasing the temperature
- Having the necessary equipment, such as a thermometer and a timer
- Having a plan for getting warm afterward
Gradually getting the body used to colder temperatures may help reduce cold shock, and having people around who can hear if someone is in distress means help is available if something goes wrong. Never try CWI when alone.
Once a plan is in place, a person can follow these steps:
- Run water into the bath until it reaches the desired depth and temperature. Remember that adding ice will mean that the temperature continues to get colder as the ice chills the water.
- Slowly submerge the body in the bath and closely monitor the body’s response.
- Set a timer to ensure that a person does not spend too long in the bath. Some research indicates that spending 11 to 15 minutes in an ice bath is the most beneficial for fatigue recovery after physical activity. However, a person should start with shorter ice baths and get out of the bath if they feel the need to.
- Get out of the water, dry the skin, and get warm again. It may be helpful to use a heated towel, change into warm clothes, or have a warm drink.
A person may want to consult a doctor before taking an ice bath or trying any method of CWI.
When to Contact a Doctor
A person should dial 911 if they or someone else experiences any of the following effects due to cold exposure:
- Rapid breathing or gasping
- Water inhalation
- Difficulty coordinating their movements
- Problems with balance or vertigo
- Dizziness or feeling faint
- Skin pain, blistering, or color changes
- Cold, pale, or blue-tinged skin
- Intense shivering or shivering that stops while other symptoms get worse
- Confusion
- Drowsiness
- Loss of consciousness
If the person is still in the bath, a 911 call responder can tell others what to do until an ambulance arrives.
The Science Behind Cold-Water Immersion
Thermoregulation and Cold-Water Immersion
As in exercise and hypoxia, cold-water exposure is a physiological challenge to the body organ systems. The body has to adjust to the cool environment to maintain the temperature in the brain and organs of the core by appropriately regulating heat production and heat loss mechanisms. The vasomotor control of skin blood perfusion through vasoconstriction and vasodilation and its role in body thermoregulation is a well-established physiological mechanism. Heat is mainly distributed to the outer layer of the skin by blood flow. The warm blood from the core is transported to the dermis of the skin through a network of blood vessels, after have penetrated the subcutaneous tissue. The venous plexus in the subcutaneous skin layer plays an important role in temperature regulation. The large volume capacity of the venous plexus makes it possible to lose heat when necessary, depending on the arterial inflow, which is regulated by the core temperature. The skin receives a continuous supply of blood from the core through the skin capillaries. While skin blood perfusion is important for tissue viability, the large changes in skin blood perfusion from full vasoconstriction to full vasodilation, especially in the acral parts of the body, are used for heat exchange between the skin surface and the environment. In the acral parts like the hands, feet, nose and ear helix, the blood from the subcutaneous arteries can be transmitted directly to the venous plexi through a network of small blood vessels called arteriovenous anastomosis, or AVAs. The AVAs are surrounded by smooth muscle that contracts and dilates to regulate the blood flow and therewith regulates the temperature in the respective skin areas they supply. These short circuit vessels are open in situations when the body needs to lose heat and are closed during heat conservation in the cold.
Vasomotor Response
Under normal environmental conditions the vasomotor response (vasodilation/vasoconstriction) is used to regulate body core temperature within the thermoneutral zone. The vasoconstriction of the peripheral blood vessels sets in at an estimated core temperature of 37.1°C when immersed in cold water and a temperature of 37.5°C when immersed in cold water post-exercise [16]. It should be noted that these participants were at the high side of normal deep body temperature. When body core temperature falls below the lower critical temperature [18], the body is unable to prevent a further fall by vasomotor control alone. In order to prevent a further fall, it has to invoke its second heat defence system, namely increasing heat production by shivering (see below). There are large individual variations in the physiological response to CWI.
Shivering and Non-Shivering Thermogenesis
Shivering is the process of continuous and asynchronous contraction of skeletal muscles in the body. Peripheral and central thermal receptors stimulate the hypothalamic thermoregulatory control centre, which mediates an effector response through supraspinal- and peripheral motor neurons. The increased muscle activity is highly energy dependent and, in consequence, causes an elevated metabolic rate. The maximum amount of heat that the body can produce by shivering thermogenesis is about 5 times greater than the basal metabolic heat production [20]. Brown adipose tissue (BAT) is capable of producing excess heat through the process of non-shivering thermogenesis.
Body Fat and Insulation
Subcutaneous fat is an important insulator of heat during cold exposure. Its insulating effect depends on the thickness of the fat layer.
Gender and Age
When body fatness and the body surface area to volume ratio are taken into account, there appears to be no differences in responses to CWI between men and women [27]. However, when comparing gender-specific cold-water responses, Solianic et al [28] found that there was a significant difference in the thermoregulatory response to CWI between men and women. Another important predictor of how the physiology of our body is influenced by cold is age. Hypothermia still remains one of the leading causes of death among older individuals [29].
Circadian Rhythm
Body core temperature in humans has a well-established circadian rhythm, where temperature varies by about 1°C throughout the day, reaching its lowest temperature at night [31]. This raises the possibility that morning CWI may increase the risk of hypothermia because of lower initial core temperature.
Lewis Hunting Reaction
The Lewis hunting reaction is one of four possible responses to immersion of the hand in cold water [15]. When extremities are immersed in cold water, the peripheral blood vessels alternate between vasoconstriction and vasodilation. The initial response is a vasoconstriction to reduce the heat loss, but this results also in reduced temperature of the extremities. After approximately 5-10 minutes of cold exposure, the sympathetic response causes blood vessels to vasodilate, a process called cold-induced vasodilation (CIVD). The CIVD response is related to a cold-induced decrease of sympathetic activity around the sphincter muscle of the arteriovenous anastomoses.