I had to use the 3M Tagaderm Film adhesive patches from the start to hold my 75 mcgs. Fentanyl patches in place. With these overlayed, you can shower without worrying about the patch coming off before the 72 hour period. Amazon has these for sale for a very reasonable price. Much less than your neighborhood medical supply house. An occasional heat rash forms just underneath the Tagaderm portion of the patch, but never under the Fentanyl patch itself. I therefore do move them around each time I change them. Primarily on the upper arm seems to be the best place followed by the upper chest above the nipple area either side.