Fentanyl Nasal Spray Online | Fentanyl Nasal Spray For Sale Online | Fentanyl Nasal Spray Online Dispensary for Pain.What is this medicine? FENTANYL (FEN ta nil) is a pain reliever. It is used to treat breakthrough cancer pain that your long acting pain medicine does not control. Do not use this medicine for a pain that will go away in a few days l