Get emergency medical help if you have any signs of an allergic reaction to fentanyl: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Like other narcotic medicines, fentanyl can slow your breathing. Death may occur if breathing becomes too weak. read more
The widespread use of fentanyl triggered the production of fentanyl citrate (the salt formed by combining fentanyl and citric acid in a 1:1 stoichiometric ratio). Fentanyl citrate entered medical use as a general anaesthetic in 1968, manufactured by McNeil Laboratories under the trade name Sublimaze. read more