A common question that I get from patients is, “Should I use ice or heat?” My immediate response is always, “It depends.” The debate of whether to use ice or heat depends on numerous factors, including the type of injury/ailment and the chronicity of the injury (i.e. time since injury onset). I will take this time to discuss the indications and contraindications for ice and heat, based on both the current research and my clinical expertise.
When to use
Since one of the reasons for cold therapy is to decrease swelling, I tend to suggest using ice during the first 48-72 hours following a traumatic injury (e.g. an ankle or knee sprain or a muscle strain) and for the first few weeks following an orthopedic surgery (e.g. total joint replacement). However, since the acute inflammatory process is a normal and necessary part of the body’s natural healing process, some inflammation is, in fact, a good thing. For this reason, some healthcare providers may argue against the use of ice following an acute injury or surgery, as they believe that it will delay or impair the recovery process by altering the body’s natural healing process. Yet, a recent study performed on rats with an induced muscle strain suggests that cryotherapy decreases the amount of cellular inflammatory markers without altering the regeneration of muscle and the surrounding tissue.5 In this study, the ice was applied for 30 minutes, every 2 hours, for the first 48 hours following the injury. 5 Based on this study, cold therapy appears to decrease the amount of inflammation, at least on a cellular level, without delaying recovery.
Based solely on the aforementioned study, I would continue to recommend that people ice following an acute injury or surgery. However, a recent systematic review of the current research concluded that there is only “marginal evidence” to support the use of cold therapy for acute musculoskeletal injuries, with “little evidence” indicating that cold therapy reduces swelling and improves joint mobility.1 A few studies found that applying ice following an acute ankle sprain allowed people return to work or their given sport more quickly, but these studies were of poor quality and, therefore, cannot be taken at face value.1
In general, the research supports the use of cryotherapy for chronic inflammatory conditions, not acute inflammatory conditions.
How to use
Precautions and Contraindications
As with most therapeutic modalities, there are some potential side effects of cryotherapy, including ice burn and temporary neuropathy (aka nerve damage) to superficial nerves (lasting from a few hours to a few months).1 These adverse events can be mitigated by following your healthcare provider’s advice, including placing at least one layer of clothing or a towel between the cold pack and your skin and not applying the cold source for longer than the recommended duration. Additionally, please consult with your healthcare provider before applying any form of cold therapy if you have any of the following conditions: sensory impairment (e.g. neuropathy, decreased sensation or hypersensitivity to cold), cardiovascular disease, hypertension (aka high blood pressure), or poor circulation (e.g. Raynaud’s disease)
I also recommend refraining from applying ice prior to exercise, as research has shown an increased risk of injury if you exercise within 30 minutes after applying ice.4 This increased risk of injury is due to impaired reflex activity and motor function, as well as impaired proprioception, which is the body’s use of joint receptors to increase one’s awareness, and subsequent control, of joint positioning.4
One of the therapeutic uses of heat is to increase blood flow to the injured area, thereby bringing fresh nutrients and oxygen to heal the damaged tissue while removing toxins and damaged tissue from the area. Additionally, by increasing the temperature of the injured or painful site, therapeutic heat can relax tense muscles, decrease pain and increase the extensibility of soft tissues.1
When to use
The current literature is scarce regarding the therapeutic use of heat. However, some research has shown that long duration (4-8 hour), low-level heat application provides short-term improvements in pain, disability, sleep, muscle stiffness, flexibility, and perceived stress in people with low back pain (LBP).6,7 It is worth noting that the research also shows that when heat is used in addition to (but not at the same time as) exercise, people with LBP experience better outcomes compared to when heat is used as the only form of therapy.1 This is likely due to the fact that, similar to heat, any form of active movement increases blood flow, thereby bringing fresh nutrients to the injured area to promote healing.
Research also shows that long duration (8 hours), low-level heat application provides significant pain relief from post-exercise delayed onset muscle soreness, which is the soreness that you typically experience for 24-48 hours after performing a new exercise or an exercise that you have not performed for awhile. One study shows that applying heat for 8 hours (applied at 18 hours and 32 hours post-exercise) improves pain levels 138% more than cold application.8 However, the study found no difference in physical function or disability levels between the application of heat versus ice.8 Therefore, while heat appears to decrease post-exercise muscle soreness, it does not appear to provide any benefits in terms of function.
How to use
Various forms of either dry or moist heat can be used, including a heating pad, a hot bath, a steam towel, or a sauna, with no one form proving to be more effective than the others. If using a heating pad, do not apply it directly to your skin, to avoid skin burns and/or ulcerations. The duration of heat application depends on the temperature and form of heat (i.e. dry vs. moist). Moist heat can be felt more quickly, allowing it to be more effective in a shorter period of time compared to dry heat. The aforementioned studies discussed the use of heat wraps that can be applied for up to 8 hours, and this is due to the fact that the temperature of the wraps is low enough to avoid skin burns. Most pharmacies and corporate supermarkets sell disposable thermal patches that last up to 8 hours, and I can personally vouch for their effectiveness in relieving LBP and tightness!
Precautions and Contraindications
Potential side effects of heat application include burns, skin ulcerations, increased inflammation, and disease progression (e.g. with RA and cancer). For these reasons, please consult with your healthcare provider before applying heat if you have any of the following conditions: sensory impairments (e.g. peripheral neuropathy), multiple sclerosis, cancer, RA, poor circulation, spinal cord injuries, and diabetes.
I also recommend avoiding the use of heat for the first 48-72 hours after an acute injury and surgery, as this is the time when the body’s natural inflammatory process is in its heightened state. While, as mentioned earlier, some inflammation during the acute stage is a good thing to promote healing, the presence of inflammatory cells is what causes increased swelling and pain. Since the application of heat in the first few days following an acute injury would increase the inflammatory process, subsequently exacerbating the swelling and pain, heat should not be applied in this acute stage.
My Personal Consensus
Based on my compilation of the evidence, my patients’ experiences, and my own personal experiences, I recommend using cryotherapy for the first few weeks following an orthopedic surgery and for any chronic inflammatory disease (e.g. RA) and experimenting with its use during the first 48-72 hours after a traumatic musculoskeletal injury. Even though the research shows limited support for cryotherapy following surgery or a soft tissue injury, not many high quality studies have been performed to date. Additionally, all of the recent studies show either no change or some improvements in pain levels, joint mobility, and/or self-selected pain medication use. Since none of the studies show any negative impacts of ice and since most of the adverse events of cryotherapy are avoidable with proper use, I believe that the application of ice is worth experimenting with, since it may provide small improvements, including temporarily numbing the pain.
Regarding heat, based on the literature, I recommend applying heat to assist with LBP and post-exercise muscle soreness. I also recommend using to heat alleviate neck pain and headaches. While there is no evidence to support the latter recommendations, oftentimes neck pain and headaches are due to increased muscle tension and/or stress. Applying heat to your neck can help to relax and loosen your neck muscles, which, in turn, may decrease your pain and the severity and/or frequency of your headaches. I also recommend applying heat for any muscular pain (except during the first 72 hours following an acute strain), since heat will relax the muscle from a spasm or tensed state. Heating a tight and/or relatively recently strained muscle prior to exercise can be particularly beneficial, as the heat will allow the muscle to be more relaxed and extensible upon initiating exercise, thereby decreasing the risk of the straining/re-straining the muscle. Lastly, in the clinic, I have found that applying heat immediately after dry needling sessions helps prevent post-needling soreness.
In general, I suggest using ice for acute injuries, following surgery, and for inflammatory diseases, while I recommend applying heat for muscle pain, neck and back pain, headaches, post-exercise muscle soreness, and after dry needling. Since there is limited research on the use of ice or heat for chronic joint pain (e.g. osteoarthritis), I recommend experimenting with both and determining which, if either, is beneficial. As long as you take the necessary precautions, there is minimal harm with experimenting! Plus, as I have found that some people respond better to one versus the other, it may be a matter of personal preference. Therefore, my answer to the original question remains, “It depends!”
Bridget End, PT, DPT
Bob Cranny, PT