有止痛功能並不能說止痛是唯一後果。2-3mg 就可引起呼吸困難甚至死亡

2-3 milligrams of fentanyl can induce respiratory depression, arrest, and possibly death.

 

https://www.fremontpolice.gov/crime-prevention/drugs-and-fentanyl-awareness#:~:text=2%2D3%20milligrams%20of%20fentanyl,skin%20rash%2C%20or%20clammy%20skin.