Mag oil isnt really oil. It's water and mag chloride flakes melted... Has an oily appearance but no oil involved. You can use it anywhere and once it dries you can wipe it off and apply lotion or whatever since The mag is only absorbed when it's moist. You can do foot soaks too.
I bought my first bottle of mag oil but make my own now. I bought 2+ lbs on amazon for 16$ and no shipping.