Someone called me the other day to ask this question again. What do you do for a sudden injury? Do you use a "hot pack" or a "cold pack?"
This seems to be something that happens a lot so we might as well get this right. Of course, most athletes are already familiar with this but you may not be.
Sprains and Strains
Cold should be applied to both strains and sprains. Cold packs (or, whatever you use to administer) are best every 4-6 hours for a few days. The reason is that cold reduces inflammation. Also, there is often cellular damage when there is inflammation because it reduces the oxygen supply to the tissue.
Finally, when you apply "cold" to a sprain or strain it acts like an anesthetic. In short, it takes away the pain.
There are a lot of them on the market and they can be purchased at drug stores and even grocery stores. However, if you do not have one, you can use a bag of frozen vegetables right out of a freezer. And, to protect your skin, you should wrap it in something such as a cloth, towel, or even a bag. Putting something that cold on your skin directly can cause frostbite and even some damage.
You don't really put "heat" to work until swelling has gone down. Generally, this takes a day or two and it may take a little longer. What heat does is stimulate blood flow and also allows tightened muscles to relax.
Once again, you should use a regimen of about twenty minutes about three times daily. You can also accommodate this with bathing or using warm compresses.
The New Stuff on the Market
Of course, companies keep coming up with newer commercial versions of products to accommodate pain. These are special "wraps" and even some "patches" that you apply to the affected area. If you prefer to use those commercial packs, that is fine.
Now, having said all of that, let's go back to arthritis pain. Generally speaking, you are better off using "cold therapy" for arthritis pain. That means other than a sprain or strain that occurs in an area other than an affected joint, should be handled using these instructions.
It would be nice if we never had to deal with these little annoyances at all. Unfortunately, we all do.