It is in the detergent isle in the super market. As I say I just put it in a pillow slip and wrap it to to affected area with a tea towel or bandage. Leave it on for about a half hour to an hour. For breast swelling I just put it in a sock and insert it into the cup of my bra. It draws fluid away, not sure how but it will be damp when you finish using it. You can reuse it again and again. It comes in either a fine powder or granules. Either works but the fine powder is more comfortable if you have a bit of pain. It comes in a plastic bag and only costs a couple of bucks. It is not the same as Epsom salts or kitchen salts. It is actually called Lectric Washing soda. Hope this explains it a bit better