Fair enough. My brother-in-law was in the hospital a little while back... heart attack. Painful. They asked him “do you want fentanyl for the pain?” - just hearing the word nearly gave him another heart attack. Needless to say he isn’t a candidate for that vaccine.
I had a colonoscopy earlier this year and they used fentanyl as a light sedative before the anesthetic. I was really surprised at that, but let them go ahead. Things turned out fine.