Hot vs. Cold Therapy

One of the most common questions I get is “Should I ice it?” (referring to an injury or an ache). Ice is the typical recommendation from an emergency room, physical therapist, chiropractor, massage therapist, etc. When I worked in ambulances, we were quick to throw ice packs on anything that was hurting. It is a common go-to, but why? Let us take a look at the basic physiology of cold and hot therapies:

Cold therapy results in vasoconstriction; the narrowing of blood vessels due to the contraction of the tiny muscle tissue within the vessels. Blood flow decreases with vasoconstriction.

Hot therapy results in vasodilation; the widening of blood vessels due to the relaxation of smooth muscles that make up the vessel walls. Blood flow increases with vasodilation.

The idea behind putting ice on an injury is that cold therapy reduces inflammation by reducing blood flow. But acute inflammation, caused by excess blood flow, moves healing entities (like plasma and leukocytes) from blood into the injured tissue for timely repair. Slowing that process with cold therapy also slows recovery, extending healing time. Using ice on an injury is akin to using Tylenol for a fever; you are stopping the body’s internal fire, which is burning for a reason. Sometimes this internal fire may get out of hand, but rarely. Let’s not preemptively put out a useful fire.

I have heard many stories about people icing injuries for weeks (“because my doctor told me too”) and are then left wondering why that injury lingers. There is a general consensus in traditional Chinese medicine that cold therapy causes stagnation of blood and energy in an injured area, making it worse. Cold congeals, heat heals! (Unless it’s too hot, of course, then it burns!)

It can be especially disastrous to use cold therapy on an injury that involves tense muscle tissue (which is most injuries). Consider a strained tendon in an inflamed twisted ankle: that tendon might have torn and caused significant blood flow to the area. The tendon is also connected to a muscle, which is contractile tissue. Using ice on that inflamed area will cause that muscle, and all the other muscles exposed to the cold, to tighten. These muscles were probably already contracting to protect the injury, and now the cold might settle that tension into a deeper holding pattern. Right now, I am writing this in a cabin that is heated with a wood stove. I have not had a fire all day, and now as the sun disappears, a chill is setting in. My whole back is taut and begging, “Make a fire already!” Cold encourages great tension in muscular tissue, no doubt about it. When we use cold therapy on an injury to reduce inflammation, we may also unknowingly cause all of the surrounding muscles to contract. And sometimes that tension can result in chronic pain.

Tight muscles lack blood flow because as the muscle fiber tightens, it decreases or cuts off the small vessels that supply the tissue (vasoconstriction; the narrowing of blood vessels). This is fine if the muscle is going through normal movement of contract-release-contract-release. But if the muscle is held in a constant contraction, the blood flow is hindered for too long. What a rigid muscle really needs is oxygen, and how it gets that oxygen is through blood. So if someone uses cold therapy on an ache that is strictly due to muscular tension, then they are only prolonging the issue by further withholding adequate amounts of blood flow from the muscle tissue by vasoconstriction. In this case, heat therapy shines because it encourages vasodilation and brings in a rush of hemoglobin-rich blood. (However, in cases of severe chronic pain, even vasodilation may not bring relief to the tight muscle because the nervous system is in a holding pattern that tells the muscle to stay contracted. This is a whole other rabbit trail. My point is that heat is generally much more helpful than cold for tight muscles!)

While scientific explanations are hunky-dory, what I really care about are actual experiences.And to be honest, it can be really difficult to know what is actually helping an injury and what is just the natural healing process of the body. I have witnessed many folks work through various injuries, and because of these experiences I feel fairly certain that cold therapy has a high probability of slowing healing, and heat therapy has a high probability of not doing damage and potentially helping things along. This confidence comes from knowing loads of people who have iced injuries for significant periods of time and had delayed recoveries (and lingering issues with that area), and also from witnessing folks use heat therapy and see daily improvement in comfort and mobility. I have learned a lot from the weeks I have spent camping with injured friends or providing first aid at gatherings, because these are unique places where I am able to monitor an injury and its treatment for many days, in person.

So is cold therapy ever appropriate?

I think cold (or rather “cool”) therapy is appropriate for moderate burns, immediately after. That’s about the only localized injury I can think of that should receive “cool” therapy (though I’m sure there are considerations I am unaware of).

Another time when I use cold therapy is when it is what someone wants and is comfortable with. Finding physical and mental comfort is an important part of injury care. So if someone really wants ice because it’s what they are used to, or they want the numbing effect, then ice is what they get! The immediate use of ice might be fairly inconsequential in the healing process because the initial inflammation is a powerful force that is only slightly dampened by ice. It is the long term, daily use of ice that poses more a problem in my mind. If someone has an injury and doesn’t have the luxury of prioritizing their healing, then ice may be used to numb the pain and allow them to function (though ibuprofen would probably be more effective as an anti-inflammatory in many cases). BUT both ice and anti-inflammatory medication will likely extend the recovery time.

Most conventional knowledge says, “do not use hot therapy on anything that is already hot to the touch”. I disagree. Even when folks have hot and oozy wounds, my first recommendation is a warm epsom salt soak (because, to reiterate, inflammation is not the problem, but is rather addressing the problem/injury/infection/tissue degradation). Now I feel I should make an important clarification: in cases of inflamed injuries, I use WARM therapy, not hot therapy. I think it is possible to aggravate inflammation with too much heat. In general though, cold is much more likely to get stuck in the body and cause long term issues, and heat is not.

Now that I have fully poo-pooed cold therapy, I want to clarify that I have been referring strictly to localized treatments. Full body cold therapy can be quite invigorating and healthy! What I am talking about it exposing the full body to cold temperatures for short periods of time, like jumping in cold water and then warming up immediately after. I do not have a shower where I live, so my bath happens in a cold creek year round, and I am finding that my body is now adapting to cold temperatures with much more ease. When the body is exposed to cold suddenly, blood flow is directed toward the core, protecting vital organs. As the body warms, fresh blood is once again directed to the limbs and the lymph fluid is given a bit of a push to pump up immune activity. Or so I’ve been told. From my experiences, it doesn’t feel great in the moment (screaming helps you get through it), but it gives me a bit of a rush afterwards and my body feels refreshed and energized. So there, cold is not all bad!

What about alternating hot-cold therapy?

I don’t know! Contrast baths or compresses has been my recommendation for folks who seem set on ice being a part of their treatment plan; I guess its my way of sneaking heat into the equation. The idea is to alternate hot and cold every 3-15 minutes, and I can see how this might encourage blood movement in the same way as the full body cold therapy described above. However, I have heard murmurings that it can reduce nerve conduction and thus slow down the body’s healing mechanisms in the long run. Also, most descriptions of contrast therapy suggest ending with cold (“for the anti-inflammatory effect”), but you can guess my thoughts on that…

Overall, I prefer to stick with just heat.

There is also a line of thought out there that suggests any temperature extreme is jolting to the nervous system, hot or cold. If the goal is to relax muscles, these extremes cause stress because the body has to rapidly adapt, so the theory says. In light of this topic, I find it worth mentioning, but I don’t usually ascribe to this in my own practice. When I place a hot (but not too hot) towel on someone’s back, I typically hear a sigh of deep relaxation (and that is my response when it is done to me).

So, how can we apply heat?

Well, I’m glad you asked. Here are brief descriptions of methods that I enjoy…

*Please don’t burn yourself! Use a temperature that is comfortable.

  1. Hot soak– Take a hot bath, or visit a hot spring, or soak an extremity in a tub of hot water, or get yourself a hot tub, or get yourself a friend with a hot tub.

  2. Hot pack-Use a hot water-bottle, or a plug in heating pad, or those microwavable rice pack thingys, etc…

  3. Epsom salt compress or soak– Epsom salt is magnesium sulfate, which helps soften tight muscles. Whenever possible I use it to enhance hot soaks or compresses.

    For a soak, add ½ cup epsom salt to a large dish tub of water.

    For a compress, add ½ cup epsom salt to 1 quart water.

    The salt will dissolve into hot water. Soak or apply the compress for 15-45 minutes. During massage sessions, I create compresses by sprinkling epsom salt on a wet towel, then exposing it to heat so the salt dissolves into the towel (I do this in a towel cabby, but a microwave would probably work too?). The hot towel can then be laid on a tension-filled area. I layer it with another hot towel, and then a dry towel to make the heat last.

  4. Castor oil pack– I don’t fully understand the magic of castor oil, but it is a beloved old folk remedy for just about anything, it seems. In this case, I am referring to applying it externally. It seems to move stagnation, circulation, and inflammation. Chemically, it is a source of ricinoleic acid, which is supposedly easily absorbed through the skin and has analgesic (pain relieving) effects. A pack is made by applying the oil to some cotton or wool fabric, placing the fabric on the intended area, and providing heat above the fabric to drive in the medicine. Keep in place for 30-90 minutes.

  5. Moxibustion– Moxa sticks are made of the herb Mugwort (Artemisia vulgaris) and are burned over the skin. It is used by acupuncturists, but can also be utilized at home. The heat from Moxa goes much deeper than a hot pack. There are many techniques for using Moxa, including burning the “cigar” over your area of interest or burning it over acupuncture points. If this interests you, do your own research and learn techniques from someone in your community. I think it is my favorite way to apply heat to the body.

  6. Steam-this can be a full body steam in the form of a sauna, or a localized steam. For a localized steam, boil water, then remove from burner and put the part of your body you want exposed over the pot, and wrap a towel around to trap in the steam. Fascial steams were once a big part of my life. I used to have acne and as a teenager, I would keep a spoon in the freezer because I thought, “Surely cold will reduce the inflammation!” Every night, I would hold it too the pimples, and it would temporarily reduce redness. In my early 20s, an herbalist friend recommended doing fascial steams. These were honestly borderline miraculous in helping to clear acne outbreaks. I didn’t use any herbs, just straight up steam for the vasodilation effect. (To get to the root of the issue, I used herbs internally).

May your injuries be ever warm, full of blood, and speedy to heal!

Resources: A Tooth From The Tiger’s Mouth by Tom Bisio.

Subscribe to our mailing list

Email Address

Content: Creative Commons 2020 Annie SewDev