We all need to practice rotating stock and it’s a hard habit to remember.<<<
Yes, that is the most important part of food storage.
Rice would work well for a frozen pak on injuries, so do Peas and Corn packages.
LOL, getting double usage, that is the reward for all the hard work and what makes it all worth while.
I am sorry that you have been hurt and need to use a pak.
We use a tube sock filled with old rice for a very convenient heat pack. Put it in the microwave for three or four minutes, you can take it anywhere, it conforms to whatever body part you put it on, and it stays warm for a long time.
I don't like to use medicine unless absolutely necessary, so when the kids have growing pains these socks come in very handy.