Sometimes its better to refrain from cold water therapy
Summary
Whole body, cold water immersion can be dangerous. Following safety protocols will reduce the risk of your ice bath, cold plunge, or winter swimming practice.
Certain medical contraindications have been described by a French physician with decades of cold water swimming experience, including cardiovascular diseases, neurological irregularities, cold allergy, and adverse interactions with some medications.
The most important contraindication to cold water therapy exposure is not wanting to practice cold water therapy.
NOTE: Nothing in this article constitutes medical advice. Consult with your medical professional about the risks and benefits of deliberate cold exposure that may apply to you.
Safety protocols for your ice bath practice
In The Dangers of Deliberate Cold Exposure (Ice Bath Safety) I wrote about the most important risks of practicing ice baths, and how to mitigate them. In summary:
ice bath sober and supervise children, to minimize the risk of drowning,
go in feet first, allowing yourself to experience the gasp reflex without your face anywhere near the water,
breathe, to minimize the risk of autonomic conflict that could confuse your heart, and
allow yourself time to rewarm before you do anything dangerous, like drive a car.
These are fairly modest safety practices that are consistent with a healthy, challenging experience. In general, the acute dangers of ice baths have been exaggerated, both on wikipedia and by some popular (but uninformed) scientists and storytellers.
Nevertheless, there may be medical reasons for certain people to be wary of extreme cold exposure. In medicine, anything that would dissuade a patient from seeking a certain treatment is called a contraindication -- i.e., a reason for avoiding a therapy that could lead to harm. This article describes some contraindications to cold plunge, including examples of the adverse experiences and incidents that I've witnessed and how they were resolved.
Contraindications to cold plunge
I recently finished a new book called Cold Water Swimming (2023) written by French gastroenterologist Nicolas Iconomidis, MD. After more than 30 years of open water swimming in the Mediterranean Sea off the coast of Marseille, Dr. Iconomidis integrated his experience, medical expertise, and understanding of the science to compile a practical guide to year-round ocean swimmers.
While his recommendations on treating jellyfish stings aren't a high priority for me, Dr. Iconomidis also included a list of contraindications to cold water immersion that are worthy of consideration. He sorts them into four categories:
cardiovascular,
neurological,
cold-related diseases, and
adverse drug interactions.
Cardiovascular
Like exercise, deliberate cold exposure is a way of stressing the cardiovascular system to stimulate growth, recovery, and resilience. However, caution is warranted to ensure that the stress is hormetic -- i.e., beneficial -- rather than injurious. The cardiovascular contraindications to cold water immersion fall into three general categories: 1) blood pressure, 2) heartbeat arrhythmia, and 3) pulmonary edema.
High blood pressure
In Ice baths, hypertension, and hormesis I described a study that showed ice baths will temporarily raise blood pressure:
Hintsala et al. (2013) from the University of Oulu in Finland measured the blood pressure response in 41 hypertensive men aged 55-65 years during 15 minutes of whole-body cold air exposure (−10°C, wind 3 m/s, winter clothes), compared to 20 men without hypertension. They discovered that short-term deliberate cold exposure will elevate systolic blood pressure by 20 mm Hg or more. The Finnish researchers concluded:
Short-term cold exposure increases central aortic blood pressure and cardiac workload, and myocardial oxygen demand slightly increases in relation to blood supply in untreated hypertensive middle-aged men. Because of the higher baseline blood pressure among hypertensive subjects, the cold-induced rise in central aortic blood pressure may increase the risk of adverse cardiovascular health effects. - Hintsala et al. 2013
The mechanisms are not difficult to deduce. Cold exposure causes vasoconstriction, which is a contraction of the smooth muscle tissues that control blood flow. To prevent heat loss through the skin of the extremities, the body redistributes blood from the limbs by squeezing it into the core. That squeeze temporarily increases blood pressure.
According to Dr. Iconomidis, in hypertensive individuals, the increased blood pressure could lead to a "severe hypertensive crisis." In his book, he described an incident in which "a 61 year old man with a history of treated hypertension, presented hypertensive crises at 210/110 mm Hg after swimming in cold water." (Iconomidis 2023, p73).
In healthy individuals, a temporary boost in blood pressure from an ice bath can result in healthy, hormetic effects. However, Dr. Iconomidis warns against acute elevation of blood pressure in individuals already prone to hypertension.
Cardiac arrhythmia
Although it can be confusing, it's important to recognize the difference between heart rate variability (HRV), which is an indicator of psychological and physiological health, and heart beat irregularity (arrhythmia). Most people think a steady heart rate is a good thing, but the fact is that the heart is not meant to beat like a metronome. Although we all understand that the heart is supposed to speed up and slow down to match demand during exercise, what most people don't realize is that tiny fluctuations in heart rate are associated with changes in breath -- even in thoughts. In Ice bath vs cold plunge for HRV, I explained the beneficial effects that an ice bath practice can have on psychological resilience by boosting HRV.
However, cardiac arrhythmia is an irregular heartbeat that is not matched to the changing needs of the body. In the case of arrhythmia, the heart might race while the body is at rest, skip a beat altogether, or insert an extra beat where it doesn't belong.
Tachycardia is when the heart beats too fast. Bradycardia is when it beats too slow. These irregularities are usually harmless, but under rare conditions they can be problematic.
The most popular authority on heart and cold water immersion is Mike Tipton, PhD, who directs the Extreme Environments Laboratory, in the Department of Sport & Exercise Science at University of Portsmouth, Portsmouth, UK. He coined the term "autonomic conflict" to describe two competing reactions within the body that happen during cold water immersion.
According to Tipton, the gasp reflex is what happens when we first begin to put our bodies in the water. It activates the sympathetic fight or flight response that prepares our bodies to face danger by increasing heart rate, releasing glycogen from the liver to fuel muscles, and expressing a surge of norepinephrine. However, the dive reflex is what happens when our nostrils are covered with cold water and it has the opposite effect. When our faces enter the water, the dive reflex slows our heart rate to conserve oxygen, presumably so that we can hold our breath for longer while we fish or forage underwater.
Tipton's concern is that conflict between the gasp and dive reflexes could exacerbate heart arrhythmia, and cause a dangerous condition such as heart failure. We should note that in in his 30 years of cold water swimming, Dr. Iconomidis has never witnessed this phenomenon. Nonetheless, he refers to Tipton's theory and cautions against diving face first into cold ocean waters. Like Morozko, Dr. Iconomidis recommends entering the water feet first.
Pulmonary edema
In medical terms, "pulmonary" refers to the lungs and "edema" refers to swelling, so you might think that pulmonary edema refers to a swelling of the lungs. That's not exactly the case. Instead, it refers to an accumulation of fluid in the passages that lead to and fill the lungs, obstructing the airway and complicating breathing.
According to Dr. Iconomidis, pulmonary edema was first observed among Navy SEALS, who experienced uncontrollable coughing, mucus production, and difficulties breathing during their intense cold water swim training. However, my own experience with pulmonary edema cross-country skiing in extreme cold conditions suggests that it is not due to cold water immersion, per se. Rather, for me there is something about breathing in too much cold air all at once that has always resulted in lung irritation. In other words, you don't have to be a Navy SEAL to experience pulmonary edema, but you probably have to be doing strenuous exercise in a cold air environment. I've never experienced airway irritation as a result of an ice bath alone.
In more severe forms, too much cold air in the lungs will provoke coughing that ruptures small blood vessels in the upper airway, causing a bloody mix of mucus and saliva to accumulate in the mouth. The resolution for me has always been to take a break, rest for a bit, and allow my lungs to calm down.
Neurological
Dr. Iconomidis cautions against cold water swimming for people who have "poorly balanced epilepsy" and/or "polyneuropathy." His concern may be that a seizure while swimming could be dangerous -- e.g., death by drowning. That might seem like less of a danger in an ice bath, compared to the Mediterranean Sea in which Dr. Iconomidis swims, but his word of caution for those who experience seizures seems significant nonetheless.
Raynaud's
Additionally, Dr. Iconomidis wrote that he has witnessed two incidents in which cold water swimmers experienced a Raynaud's attack during cold water immersion. Raynaud's is a complex interaction between between thermoreceptors, the nervous system, and thermal perception that causes a cold hypersensitivity typically accompanied by anxiety. For example, vasoconstriction during Raynaud's can be extreme, causing the fingers to turn white or gray.
There are at least two types of Raynaud's, one that can respond well to exposure therapy and one that does not. In the first type, structured breathing exercises and cold coaching can often guide a sufferer through a successful ice bath. For example, in this video Can you ice bath with Raynaud's? a woman taking an ice bath describes the Raynaud's attack she experienced in 60F temperatures outdoors with her family during the winter.
The video is remarkable because she is recounting the story while plunged up to her neck in very cold water.
She says, "Look at me now, I'm sitting in 40 degree (Fahrenheit) water, and my hands are not white and they're fully circulated!"
Although her recovery from Raynaud's is exceptional, it didn't happen all at once. First she witnessed others in the ice bath. Then she successfully completed partial immersion, finally plunging down to her armpits before she achieved the comfort level on display in the video. Her experience was consistent with the recommendations in studies of exposure therapy that favor a gradual introduction of stress to acclimate the sufferer to increasingly challenging conditions in a process called stress inoculation.
Anorexia
Although Dr. Iconomidis doesn't mention it, anorexia nervosa deserves particular mention. The body dysmorphia and obsession with lean body composition that are characteristic of anorexia are very dangerous. Mortality rates among those suffering from it are higher than any other mental disorder and recovery rates are poor (Arcelus et al. 2011, van Eeden et al. 2021). Long before ice baths became popular among biohackers, anorexics were incorporating them into a set of ill-advised practices associated with their disorder (e.g., Smith et al. 1983). One survey found that more than half of respondents with an eating disorder endorsed deliberate cold exposure in some form as a method to promote fat loss (Reas et al. 2019). Nevertheless, deliberate cold exposure is nutritionally demanding, and no program of cold water immersion should be undertaken until a diet that meets minimum caloric and micronutritional demands is established. To that extent, recent case studies have revealed that a ketogenic diet has succeeded in resolving anorexia where other diets have failed (Scolnic 2017, Norwitz et al. 2023).
Cold-related diseases
I didn't know there was such a thing as cold-related diseases until I'd read about them in Dr. Iconomidis' book. I'd witnessed some adverse reactions, but I didn't know they all had medical names and descriptions. Dr. Iconomidis describes three: 1) cold urticaria, 2) cryoglobulinemia, and 3) "non-frostbite cold injury."
Cold urticaria
Urticaria is an itchy rash that appears on the skin as a result of cold exposure. Dr. Iconomidis recommends discontinuing deliberate cold exposure when you experience cold urticaria. However, I know two people who decided to do the opposite. Both reported to me that they experienced hives on parts of their skin that were submerged in the ice bath. Both expressed a determination to continue with their cold practice to discover whether the symptoms were persistent, or if there was something they could change in their breathing, their exposure, or their recovery that would mitigate the phenomenon. Both reported that the cold urticaria resolved itself after additional sessions.
Cryoglobulinemia
Neither I nor Dr. Iconomidis has ever witnessed an incident involving cryoglobulinemia. Evidently, there is a phenomenon in some people in which cold temperatures can cause an increase in risk of hypercoagulation in the blood -- which sounds to me like something that should compel you to seek the medical advice from your doctor before you undertake whole-body cold-water immersion.
Non-frostbite cold injury (NFCI)
Frostbite occurs when the water inside skin cells freezes into ice. It is a very painful condition that can result in permanent damage - especially to fingertips and toes. Although there is a remarkable species of tree frog that can be frozen solid and will spring back to life upon thawing (Moalem 2007), as you can probably imagine human flesh is not amenable to such treatment. In extreme cases, frostbite can necessitate amputation of extremities.
One of the inherent advantages of the ice bath, compared to frigid air cryotherapy, is that the temperature of the water in the ice bath can never be cold enough to freeze the water inside skin cells, because the freezing point of water in the skin is lower than that of the water in the ice bath -- with one notable exception. It is possible to lower the freezing point water in the ice bath by adding salt.
Because Morozko recommends adding Epsom salt to the ice bath to both soften the ice and confer transdermal magnesium benefits, it probably made sense to two of our engineers to dump an entire 18lb bag into the Forge in our Phoenix AZ studio. What did not make sense was turning the temperature controller down to 30F.
In my article Epsom salt makes ice baths better, I described the dangers of overdoing your cold water immersion in salt water.
The freezing point of human blood was established back in 1930 as 31F (-0.55C). Thirty years later, two courageous British scientists sought to measure the freezing point of their own pinky fingers by applying a tourniquet to cut off blood flow while holding them in cold brine (28.6F, or -1.9C) for 7 straight minutes. They reported that each finger, when removed, "felt and sounded hard when tapped with a piece of wood" (Keatinge & Cannon 1960).
Hours after dropping the temperature controller, our intrepid Morozko engineers followed in the footsteps of these two British scientists and plunged their whole bodies into an ice bath filled entirely with 18" of slush.
I got a call from one of them two days later, asking me why they felt like they had been sunburned over their entire body from the neck down. They were experiencing something called frostnip, which is a mild and reversible case of frostbite. They both recovered fully after a couple more days.
Non-frostbite cold injury (NFCI) is a little bit different from frostnip. According to Dr. Iconomidis, "It is a condition that affects the microcirculation of the hands and especially the feet," and has been observed as a loss of sensitivity in the extremities during cold, and pain upon rewarming that feels like pinpricks in the affected areas.
I sometimes get an email or a phone call from a customer who reports pinprick pain followed by a loss of sensation in their fingertips that persists for several days. Although I had never thought of their condition as an "injury," their concern seems understandable. In every single case, the practitioner elected to continue doing ice baths, but protect their fingertips from the extreme cold by either tucking them under their armpits or leaving them out of the water. In every case, feeling was restored in their fingertips in about a week.
Recall that the fingertips are at the extreme end of the circulatory system. It is in the fingertips that vasoconstriction acts first, so people who have yet to acclimate to whole body ice baths may experience an extreme form of vasoconstriction in their fingertips. While it's probably medically incorrect to say that the capillaries in their fingertips get temporarily stuck in vasoconstriction, it is probably alright to suggest that the cold exposure is causing a remodeling of their circulatory system in the extremities that takes time to complete. Only after circulation is fully restored to the fingertips can full sensation return.
Adverse drug interactions
In addition to the admonition to cold plunge only while sober, Dr. Iconomidis describes several other contraindications that are associated with drug interactions. Two prescription drug classifications merit specific mention: sedatives/relaxants and anti-depressives.
Dr. Iconomidis cautions against attempting cold water swimming while under the influence of muscle relaxants or sedatives like benzodiazepines (e.g., Valium, Xanax). It hardly seems necessary to go into further detail, as it's difficult to imagine anyone feeling motivated to undertake a swim through the cold ocean after taking Valium for back spasms. However, these drugs are also sometimes prescribed for the anxiolytic (anti-anxiety) effects and it is here that they should be treated with caution when combining with cold water.
Research from Tipton's lab in the United Kingdom has documented the salubrious effects of winter swimming for lifting mood and resolving major depressive disorders. I described the details, including some remarkable testimonials, in Can cold water cure depression? Because deliberate cold exposure is so effective for lifting mood, people taking sedatives to treat anxiety, panic, or depressive disorders might also want to experiment with cold water immersion. In that case, it would be prudent to heed Dr. Iconomidis' advice and avoid cold water swimming, which requires sufficient energy to keep the body afloat, and instead enjoy cold plunge in the bath while in repose -- e.g., face up, head above water.
Regarding anti-depressives, we have very little data. As I wrote in Couples Cold Therapy: ice bath love, a brief experience of cold water immersion will stimulate expression of neurotransmitters and hormones that lift mood. Among these are dopamine, norepinephrine, vasopressin, oxytocin. However, serotonin effects have also been observed. The interaction between selective serotonin reuptake inhibitors (SSRI) and cold exposure are unknown. Dr. Iconomidis mentions citalopram and escitalopram (e.g., Lexapro) as specific contraindications to cold water swimming, although he doesn't explain the mechanisms or rational for his recommendation.
I've witnessed hundreds of ice bath sessions and I've never asked anyone whether they were taking an anti-depressant medication. I have no data on whether being on SSRI's changes the quality of the experience, so I'd be glad to hear from anyone who has personal knowledge or experience with interactions. Until I get more reliable information, its seems prudent to advise those taking anti-depressants to consult with your medical professional regarding the possibility of adverse interactions between your medications and deliberate cold exposure.
The most important contraindication of them all
One of the fundamental tenets of Morozko's practice of ice bathing is no coercion. We encourage everyone to enter and exit the ice bath of their own volition, without bullying, shame, or social pressure.
You will never see anyone on our team standing next to a Morozko with a bullhorn, screaming "Breath motherf***er!" That approach might work for some people, but it's not part of a our practice.
The reason might be surprising.
In Stress vs Cold I wrote that the story you tell yourself is more important than the experience you have:
In fact, training yourself to overcome the stress response to cold exposure may save your life. In her 2013 TED talk 'How to make stress your friend', Stanford Psychologist Kelly McGonigal reports that it is not stress that kills you. It is the story you tell yourself about that stress.
According to McGonigal, subjects who believe their stress responses is helpful maintain more relaxed blood vessels during stress, despite an increased hear rate. She says, "My goal as a health psychologist has changed. I no longer want to get rid of stress from your life. I want to make you better at stress."
A critical dimension of learning to manage stress response is practicing choice. That is, to be able to say "I am choosing this stress, because it will make me stronger."
Stress without choice could result in trauma and the prohibition against coercion in the Morozko Method exists to minimize the risk of creating that trauma.
Therefore, the most important contraindication to deliberate cold exposure is not wanting to do deliberate cold exposure.
UPDATE 15 May 2023
I got a call from a customer this morning who tells me that this month they're celebrating their first anniversary of receiving their Morozko. He loves doing three minutes at 33F every day.
He also said that he discovered that the sensation of the ice bath is different if he's taken opioids for back pain the night before.
"The opioids only last for about four hours," he said. "I can feel them kick in about an hour after I take them, and then they give me relief from back pain for about three hours, and then they fade. So if I take them the night before and do my Morozko the next morning, They should be out of my system. "But the sensation is way different in the ice bath the morning after I've taken my pain medication. My body feels a way increased sensitivity to cold."
Although this type of experience doesn't seem to be what Dr. Iconomidis had in mind when he listed pain meds as a contraindication for cold water swimming, the experience of this customer might inform others about what to expect even after their meds have worn off.
About the Author
Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience.