So what’s the logic behind whether you apply cold or heat to a swollen body part?
I was under the impression that cold is best if you want to reduce swelling because it constricts the blood vessels, but my girlfriend has some painfully swollen lymph nodes along with her flu, and the Mayo Clinic website says you should apply hot compresses. Won’t that just promote blood flow and therefore swelling?
It depends on what symptom she is trying to relieve. Heat can reduce pain and pruritus. Cold reduces inflammation & redness but also reduces blood flow so it may be contraindicated in some cases.
Immediate reduction of swelling from trauma can limit the damage to tissues not already damaged by the trauma itself. Cold can accomplish this. As far as I know, and IANAD, other than 12 to 24 hours after a trauma cold is not generally used.
I think that cold impedes body processes and heat accelerates them, in a rough way of speaking. Shortly after an injury one of the body processes is the release of extra liquid that causes swelling which can itself become another problem, so cold will reduce this effect. Resorption of the liquid happens later and more slowly, and applying heat later will help this occur. I think other situations where you want to retard the earlier process and speed the later process call for a similar strategy. Not confidently sure, tho…