When to Use Heat and Cold for Pain
(Originally published as an article for Imbue Pain Relief Patch)
From a Chinese Medical perspective, all pain is caused by same basic mechanism: stagnation. Blood, lymph, energy, food, or other substances are inhibited from their usual flow, and this feels uncomfortable – whether it’s the result of a crushing your finger with a hammer, cramming too much turkey into your stomach, or tight shoes inhibiting circulation in your feet. Practitioners of Chinese Medicine almost always employ heat, rather than cold, to treat pain, because cold inhibits movement and heat encourages it. Maybe you remember this from your high school chemistry class – it’s basic thermodynamics. Heat is an expression of molecular movement. The hotter something is, the more its atoms are jostling around. The colder something is, the less movement is occurring on an atomic level. You may also remember from your science books that absolute zero, the temperature at which all movement theoretically ceases, is about 460 degrees below zero (Fahrenheit).
Because cold inhibits movement, it can numb an area to the point that pain signals cannot be transmitted to the brain. While this may be useful for pain that is unbearable, when the cold is removed, the pain usually returns. The cold hasn’t done anything to encourage healing, and, in most cases, there is no significant or lasting benefit.
Heat, on the other hand – in the form of moxa (which I covered in a previous article), a heat lamp, a hot water bottle, hot stones, sun, etc., opens blood vessels and pores, and enhances flow. The two main functions of flow are analogous to taking out the trash and bringing home the groceries. All cells produce waste, such as carbon dioxide, that must be taken away; and all cells need nutrients, such as oxygen, that must be delivered continuously. Many painful conditions involve a localized condition of malnourishment – because oxygen and other nutrients aren’t getting in – and toxicity – because carbon dioxide and other wastes aren’t getting removed. Besides restoring flow, heat usually just feels better.
However, there are three times I advocate the use of cold application for pain and here they are:
(1) During the first 24 hours after a significant trauma, such as a sprain. The flow-inhibiting quality of the cold in this case will help reduce the massive influx of fluid that is part of the inflammatory process. After 24 hours, though, we need to get this fluid out, we need to clear out cellular debris, and we need to encourage the flow of fresh blood to the area so the tissue can be fed and repaired. And for this, heat will be best.
(2) Briefly, after prolonged low-level strain. When I was just beginning my medical practice, I took a job doing massage at a spa to earn some extra money. After several straight hours of massage, my forearms, wrists, and hands would be hot and sore. I intuitively felt drawn to run them under cold water, even though my Chinese medical training was so heat-oriented, and it helped. Even just a splash of cold water, and within minutes, my arms and hands felt revitalized.
Many occupations carry a risk of repetitive strain injury (RSI) because they entail doing the same motions over and over, or holding a particular posture for a long time. Although you may not feel injured by a single day’s work, the cumulative impact can amount to a significant trauma. Applying cold briefly, when you take a break and again at the end of the day, may reduce the damage. However, it’s worth mentioning that managing an RSI involves more than just cold packs. You may need to adjust your form or technique, improve the ergonomics of your work station, stretch before and after work, properly rest the injured part, and get some focused therapy (such as massage and/or acupuncture), to name a just few. This is very important if you plan to continue with an activity that causes repetitive strain.
(3) Alternating with heat. While I don’t often prescribe cold application for pain, I believe there is considerable value (and greater versatility) in the use of alternating hot and cold. When we use cold and warmth alternately, this causes blood vessels to dilate (open) and constrict (close) repeatedly, forcibly pumping fluids through the region. Some would argue that alternating heat and cold works better than heat alone.
There are many viewpoints on alternating heat and cold, regarding how many minutes of each should be used and what temperatures are best. The best temperatures are usually the hottest you can tolerate (without risking burning yourself) and the coldest you can tolerate (without risking frostbite). The most common prescription is three minutes of heat followed by one minute of cold, repeated for 20 to 30 minutes, twice daily. This is done using hot/cold packs, basins of water, or even a shower, if you’re brave. When alternating heat and cold are applied for an acute injury, it is common to end with cold, leaving the cold application for several minutes (or until it warms up to body temperature). When performed for a longstanding condition, I prefer to have people end with heat.
Give it a try, diminish your pain, and tell me about your experience in the comments section below.
Copyright 2012 by Peter Borten. No reproduction in any form without permission.