Epsom salt is a chemical, magnesium sulfate (Mg SO4), that is widely used by athletes to soak sore muscles and sprains. It can even be used as a laxative, when dissolved in water and swallowed. You can find it on the shelves at most pharmacies. It keeps forever (unlimited shelf life), so it's always on hand if you buy a lot.
I would try any of the main pharmacies, like CVS, Walgreen's, etc.
I would try any of the main pharmacies, like CVS, Walgreen's, etc.