Why do some refuse certain medications?

I’ve been seeing that some POTS patients are against taking metoprolol, one even refused the prescription multiple times, which is what I am currently taking. I’m curious about why some refuse to take this or other beta blockers? My physical therapist was also concerned about my prescription. (Disclaimer: I should add that if I plan to make changes to my health plan I would talk to my doctor, I’m just curious is there is something I’m not aware of).