As I continue forward in my podiatry career, I continue to have a similar question asked of me often: Is it better to put heat or cold on an area of injury? This question pertains to people coming in with a new pain, old pain, surgery pain, the whole gamut.
There are some keys points to consider in answering this question that we must address to more fully understand the answer.
Much of the new onset pain I see is associated with some sort of inflammation. Inflammation is a mechanism in which the body attempts to heal, splint, repair an injured area and to eradicate any causative factor like infection or other cause of inflammation. Inflammation puts physical pressure on nerves and the pressure on nerves is what causes the pain.
The way inflammation happens is that on a cellular level some damage occurs. When the damage occurs to a cell, the cell gives off signals. These signals prompt the immune system to send healing cells and fluid to the area. Two of the main ways this happens is 1. vasodilatation (enlargement) of blood vessels that allow cells to migrate through a more permeable vessel wall 2. leakage of fluid directly from damaged vessels.
Now it is important to note that inflammation is a natural and necessary part of healing, so it is not always a bad thing depending on other factors. Inflammation from underlying autoimmune diseases and other types of long standing inflammation are undesirable so inflammation is not always a good thing either!
Now back to our main point and why any of this matters. Is it actually better to put heat or cold on an area of injury?
The long answer: Heat has a tendency to enlarge vessels and will create an increase in swelling and pain due to more fluid buildup and leakage of fluid/cells into the area of injury. Cold has a tendency to constrict blood vessels and will not only slow the buildup of inflammation, but will help milk fluid away from the area of injury further reducing inflammation/pain/swelling.
The short answer: In general, cold therapy is better than heat therapy when treating an area of injury.
There is a lot more to consider such as how to use cold therapy, when is heat actually better than cold (muscle spasms)? Much can be found on further investigation of these issues with simple internet searches or visit to your local library!